Industrial Pressure Transmitters

Industrial pressure transmitters for the process pressure measure, monitor and control application.

Industrial Process Pressure Transmitters

Industrial pressure transmitters are sensors with electrical transmission output for remote indication of pressure. Process transmitters differentiate themselves from pressure sensors through their increased range of functionality.

They feature integrated displays, offer high measuring accuracies and freely scalable measuring ranges. Communication is via digital signals, and waterproof and explosion-proof certifications are available. Through connection to diaphragm seals, they are suitable for the harshest operating conditions. Ideal for OEMs, process applications, water processing, and industrial pressure applications.

Sino-Inst offers a variety of pressure senors for industrial pressure measurement. If you have any questions, please contact our sales engineers.

Featured Industrial Pressure Transmitters

Diffused silicon Gauge Pressure Transmitter
A gauge pressure (GP) transmitter compares a process pressure against local ambient air pressure. Gauge pressure transmitters have ports to sample the ambient air pressure in real-time.
Capacitive Gauge Pressure Transmitter
Gauge pressure (GP) transmitters compare process pressure with local ambient air pressure. Gauge pressure transmitters have ports for real-time sampling of ambient air pressure.
Explosion-proof Pressure Transmitter
Explosion-proof Pressure transmitter, or explosion-proof pressure transducer, with the explosion-proof enclosure.
For applications in hazardous areas.
Diaphragm Seal Pressure Transmitter
When the process medium should not come into contact with the pressured parts of the measuring instrument. Diaphragm sealed pressure transmitters are used for pressure measurement.
Hygienic / Sanitary Pressure Transmitter
Also called Hygienic pressure Transmitters, or tri clamp pressure transmitter. Sanitary pressure Transmitters is used to food &beverage or pharmaceutical application.
High-Temperature Pressure Transmitter
High-temperature pressure transmitters with a 4-20mA output.
which has a temperature capability of over 850 °C and is not pyroelectric.

Absolute Pressure Transmitter
Absolute pressure transmitter with 4-20mA output for measuring pressure with absolute type reference. Absolute pressure (AP) transmitter is a measure of the ideal (complete) vacuum pressure.
Hydrostatic pressure transmitter
Hydrostatic pressure transmitter is used for fluid hydrostatic pressure measurement. With working static pressure up to 32Mpa, for liquid, gas or steam .
Remote Diaphragm Seal Pressure Transmitter
Remote seal pressure transmitter, with capillary and diaphragm seal, remote mount. Diaphragm seal systems protect pressure transmitters from hot, viscous, contaminated or corrosive media.

Sino-Inst also provides repair services for Industrial pressure transmitters. Such as WIKA, Rosemount, and other brands of pressure transmitters.

What is a smart pressure transmitter?

Digital smart pressure transmitter is pressure sensor with a 12-bit or higher microprocessor. Smart pressure transmitters are high performance microprocessor-based transmitters with flexibility. Pressure calibration and output, automatic compensation.

Smart pressure transmitter also called intelligent pressure transmitter.

The intelligent Industrial pressure transmitters consist of two parts: a smart sensor and a smart electronic board.

The smart sensor part includes: a capacitive sensor. A measuring diaphragm detection circuit. A temperature sensor, and a temperature compensation circuit.

The smart electronic board includes: a microcomputer controller. And the peripheral circuit, complete the pressure signal to 4 ~ 20mA dc conversion.

Smart Industrial pressure transmitter is used to measure the pressure of liquid, gas or steam. And then convert the pressure signal into 4 ~ 20mA DC signal output. The intelligent pressure transmitter produced by Sino-Inst can communicate with the HART communicator. It is widely used in weakly corrosive liquids in industrial pipelines, Gas and steam measurement and control systems.

Industrial pressure transmitters Working Principle

Principle and Application of Diffusion Silicon Pressure Transmitter

The pressure of the measured medium directly acts on the diaphragm of the sensor (stainless steel or ceramic). Causing the diaphragm to generate a micro-displacement proportional to the pressure of the medium. The resistance value of the sensor changes. The electronic circuit detects this change and converts and outputs a standard measurement signal corresponding to this pressure.

Principle of capacitive pressure transmitter

Capacitive pressure transmitter is mainly composed of capacitance sensor and circuit board. The sensor implements pressure-capacitance conversion. The circuit board converts the capacitance to a two-wire 4-20mA.

When the process pressure is applied to the isolation diaphragm from both sides (or one side) of the measuring chamber, it is transferred to the central diaphragm of the chamber through the silicone oil filling liquid. The central diaphragm is a diaphragm with tensioned edges.

Under the action of pressure, a corresponding displacement is generated. This displacement creates a change in differential capacitance!

And through the adjustment, oscillation and amplification of the electronic circuit board! Converted into 4-20mA signal output! The output current is directly proportional to the process pressure!

Types of Pressure Transmitters

Depending on the type of pressure to be measured:

Pressure transmitter types include gauge pressure, absolute pressure, and differential pressure. Gauge pressure refers to the pressure that is less than or greater than atmospheric pressure based on the atmosphere. Absolute pressure refers to the absolute zero pressure as the reference and is higher than the absolute pressure. Differential pressure refers to the difference between two pressures.

According to the working principle of the Industrial pressure transmitters:

  • Strain Gauge Pressure Transducers
  • Capacitance Pressure Transducers
  • Potentiometric Pressure Transducers
  • Resonant Wire Pressure Transducers

Electrical Output of Pressure Transducers

Pressure transmitters are generally available with three types of electrical output. Millivolt, amplified voltage and 4-20mA. Below is a summary of the outputs and when they are best used.

Extended Reading: 4-20ma pressure transducer wiring diagram

Millivolt Output Pressure Transducers

A sensor with a millivolt output is usually the most economical pressure sensor. The output of a millivolt sensor is nominally about 30mV. The actual output is proportional to the input power or excitation of the pressure sensor. If the stimulus fluctuates, the output will change.

Because of this dependence on the level of excitation, a regulated power supply is recommended for millivolt sensors. Because the output signal is so low, the transducer should not be placed in an electrically noisy environment. The distance between the transducer and the reading instrument should also be kept relatively short.

Voltage Output Pressure Transducers

Voltage output transducers include integral signal conditioning, which provides higher output than millivolt transducers. The output is usually 0-5Vdc or 0-10Vdc. Although model-specific, the output of the transducer is usually not a direct function of the stimulus. This means that as long as the regulated power supply falls within the specified power range, it is usually sufficient. Because of their higher output levels, these sensors are not as susceptible to electrical noise as millivolt sensors and can therefore be used in more industrial environments.

4-20 mA Output Pressure Transducers

These types of sensors are also called pressure transmitters. Because 4-20mA signals are least affected by electrical noise and resistance in the signal line, these sensors are best used when signals must be transmitted over long distances. These sensors are typically used in applications where the lead must be 1000 feet or more.

Industrial Applications of Pressure Transmitters

Pressure transmitters are mainly used in the following areas:

  1. Petroleum, petrochemical, chemical. Matching with throttling devices to provide accurate flow measurement and control. Measures pressure and level in pipes and tanks.
  2. Electricity, city gas. And other companies and businesses require high stability and high precision measurement and other places.
  3. Pulp and papermaking are used in places that require chemical-resistant liquids and corrosion-resistant liquids.
  4. Steel, non-ferrous metals, and ceramics are used in furnace pressure measurement and other places that require high stability and high precision measurement. They are also used in places that require stable measurement under strict control (temperature, humidity, etc.).
  5. Machinery and shipbuilding, used to strictly control the place where high precision is required for stable measurement.

Hydrostatic pressure for level measurement:

SI-151 Hydrostatic Level Sensor
SMT3151TR Hydrostatic level transmitter-Rod Type
SI-PCM260 Deep Well Water Level Sensor

Pressure Transmitters VS Pressure Sensors VS Pressure Transducers

A pressure sensor is a device or device that can sense a pressure signal and convert the pressure signal into a usable output electrical signal according to a certain rule.

A pressure sensor usually consists of a pressure-sensitive element and a signal processing unit. According to different test pressure types, pressure sensors can be divided into gauge pressure sensors, differential pressure sensors and absolute pressure sensors. A pressure sensor is the core part of pressure transmitter.

In a pressure transducer, a thin-film or piezo-resistive pressure sensor is mounted on a process connection. The transducer converts pressure into an analog electronic output signal, typically as a millivolt per volt output. These signals are not linearized or temperature compensated.

A pressure transmitter has additional circuitry that linearizes, compensates, and amplifies the signal from a transducer. The different signal types are typically voltage signals (eg, 0 to 5 or 0 to 10 volts), milliamp (eg, 4 to 20 milliamp), or digital. The instrument then can transmit the signal to a remote receiver.

If you still don’t know how to choose the right pressure transmitter. Please feel free to contact our sales engineers. We will provide you with the best pressure measurement and control solution.

Guidelines for Troubleshooting Pressure Transmitters

When this happens, you should consider: Is the pressure source itself stable? The degree of anti-interference ability of the instrument or pressure sensor. Is the sensor wiring normal? The sensor itself is vibrating and the cause of the failure. Is the polarity of the power supply reversed?

Check the degree of pressure variable; make 4-20mA output adjustment.

Check the transmitter’s power supply voltage, calibration equipment and set values (4mA and 20mA points). Check whether the pressure interface is leaking or blocked. Check the wiring mode and power supply. If normal, check if the sensor has zero output. Or Perform a simple pressurization to see if the output changes. If there is a change, the sensor is not damaged.

Check if pressure transmission is blocked; check calibration equipment and adjust sensors; check vehicle damping and electromotive force interference.

Frequently
Asked
Questions

1. Do a 4-20mA trimming first to calibrate the D / A converter inside the transmitter. Since it does not involve sensing components, no external pressure signal source is required.

2. Do a full fine-tuning again to make the 4-20mA, digital reading coincide with the pressure signal actually applied. So a pressure signal source is needed.

3. Finally, do the re-ranging, and adjust the analog output 4-20mA to match the external pressure signal source. Its role is exactly the same as that of the zero (Z) and range (R) switches on the transmitter housing.
The communicator can change the range of the intelligent pressure transmitter. And can adjust the zero point and the range without inputting a pressure source. However, this method cannot be called calibration and can only be called “setting the range”. True calibration requires a standard pressure source input to the transmitter.

Adjusting the range (LRV, URV) without using a standard is not calibration. And ignoring the input part (input transmitter pressure) for output adjustment (transmitter conversion circuit) is not a correct calibration. Furthermore, the relationship between the pressure and differential pressure detection components, the A / D conversion circuit, and the current output is not equal. The purpose of calibration is to find the changing relationship between the three.
Emphasize one point:
Only when the input and output (input transmitter pressure, A / D conversion circuit, loop current output circuit) are debugged together, can it be called a true calibration.

First of all, the parameters that must be seen when purchasing a pressure transmitter are:
Pressure range. Range. Measurement medium. Installation method-threaded flange clamps, etc. Installation dimensions. Temperature. Whether with display. Whether with HART protocol. Output type. Current output or voltage output. Explosion-proof level, protection level. Accessories. Mounting bracket.
The above parameters will affect the price of the pressure transmitter.
Sino-Inst, as the manufacturer of pressure transmitter, offer you with the best price.

The input of the pressure transmitter is a pressure signal. The function of the pressure transmitter is to convert the pressure signal input from the outside into a current or voltage signal.

A pressure transmitter is a device that converts pressure into pneumatic or electric signals for control and remote transmission.

It can convert physical pressure parameters such as gas and liquid sensed by the load cell sensor into standard electrical signals (such as 4~20mADC, etc.). Measurement, indication and process adjustment are carried out by supplying secondary instruments such as indicating alarms, recorders and regulators.

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Sino-Inst offers over 20 industrial pressure transmitters.
A wide variety of industrial pressure transmitters options are available to you. Such as free samples, paid samples.
Sino-Inst is a globally recognized manufacturer of industrial pressure transmitters, located in China.
Sino-Inst sells through a mature distribution network that reaches all 30 countries worldwide.
Industrial pressure transmitters products are most popular in Europe, Southeast Asia, and Mid East. You can ensure product safety by selecting from certified suppliers. With ISO9001, ISO14001 certification.

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SI-3151GP Capacitive Gauge Pressure Transducer

Gauge Pressure Sensor (GP) is a pressure transmitter for Gauge pressure measurement. SI-3151GP Capacitive Gauge Pressure Transducers use capacitive sensing elements to measure gauge pressure.

Gauge pressure (GP) transmitters compare process pressure with local ambient air pressure. Gauge pressure transmitters have ports for a real-time sampling of ambient air pressure. There are different types of pressure measurement. Such as gauge pressure, absolute and differential pressure measurement. Among them, the gauge pressure measurement is performed using a gauge pressure transmitter. These devices are designed to measure pressure relative to ambient atmospheric pressure. The output of the gauge pressure sensor will vary depending on the atmosphere or different altitudes. Measurements above ambient pressure are expressed as positive numbers. And negative numbers indicate measurements below ambient pressure. At Sino-Inst, we offer gauge pressure transmitters for a variety of industrial applications.

Sino-Inst offers a variety of Gauge Pressure Transmitter for industrial pressure measurement. If you have any questions, please contact our sales engineers.

Features of 3151GP gauge pressure transmitter

  • High-reliability micro-capacitance silicon cell
  • Long Term stability: +/- 0.1% URL / 10 Years
  • High accuracy, up to +/-0.04% of calibrated span (0.065% as standard)
  • Versatile indicator with push-button programming
  • Exceptional resistance to harsh environments
  • Hart® 5.2 multi-drop communication
  • Field repair possible with common spare parts
  • The built-in loop calibration facility
  • Large installed base
  • Exia “Intrinsically safe” or Exd “Explosion proof” versions ex stock
  • SIL2 (EN61508)

Specifications of 3151 gage pressure(GP) transmitter

Model3151GP
Measurement span0-0.10~3.5kPa(0-10~350mmH2O)
0-0.8~8.0kPa(0-80~800mmH2O)
0-4.0~40kPa(0-400~4000mmH2O)
0-20~200kPa(0-2000~20000mmH2O)
0-70~700kPa(0-0.7~7kgf/cm2)
0-210~2100kPa(0-2.1~21kgf/cm2)
0-700~7000kPa(0-7.0~70kgf/cm2)
0-2.1~21MPa(0-21~210kgf/cm2)
0-4.1~41MPa(0-41~4100kgf/cm2)
Reference accuracy
(Varies by material and measurement span)
± 0.1%, ±0.075%
Fill fluidSilicone oil (general purpose models), fluorine oil (oxygen and chlorine models)
Waterproof and dust-proof constructionIEC IP66/IP67
Explosion-proof constructionTIIS flameproof (Exd IICT4)
KOSHA flameproof
FM explosion proof, intrinsic safe and Nonincendive
ATEX/NEPSI/IECEx flameproof, intrinsic safe and Type n
INMETRO flameproof
Wetted materialSUS316 (diaphragm SUS316L), Hastelloy C, Tantalum
Power17.9 to 42V DC
Output signal4 to 20 mA DC (SFN communication)
4 to 20 mA DC (HART® communication)
MODBUS-485 signal
Process connectionsRc 1/2 or 1/2 NPT internal thread
Safety certificationSafety Integrity Level (SIL) 2 certification

By selecting from a large range of materials, we are able to customize the transmitter and supply remote seals.

We temperature compensate for the whole assembly to maintain the highest level of performance.

Selecting from 316SS, Hastelloy, Monel, Tantalum, Gold, and Ceramic.

We can custom build a transmitter to our own high standards, or to your individual specifications.

To provide high flexibility, remote seals can be fitted to any of the SI series of transmitters.

For further information, please Contact us.

Gauge Pressure Sensor Applications

Pressure transmitters are used to measure level, density, and pressure of liquids, gases or vapors. And then converted to a 4-20 mA DC signal output. The SI-3151 GP intelligent pressure transmitter can communicate with the HART Communicator.

There are many types of pressure sensors, which are widely used in:

Water plants. Oil refineries. Sewage treatment plants. Building materials. Light industry. Machinery and other industrial fields.

To achieve the measurement of liquid, gas, steam pressure.

However, different pressure sensors are required for different applications.

The pressure sensor can be used to measure some mechanical physical quantities such as: Displacement. Vibration. Angular velocity and acceleration.

It is also widely used in the measurement of thermal engineering parameters such as: Pressure. Differential pressure. Liquid pressure. And content of ingredients.

Gauge Pressure Sensor working principle

What is gauge pressure?

Gauge pressure, also known as ‘relative pressure’ or ‘vented gauge pressure’. Gauge pressure is the measurement of pressure relative to atmospheric or barometric pressure.Gauge pressure sensor has the back of the sensing element open (or ‘vented’), to provide a reference to atmospheric.
More about the Difference between absolute, gage and differential pressure.

How does a gauge pressure sensor work?

Gauge Pressure Transmitter / transducer (GP) is a pressure transmitter for Gauge pressure measurement. According to the measurement principle, it can be divided into: capacitive and diffused silicon.

Capacitive pressure sensor (capacitive type pressure transducer) is a pressure sensor that uses a capacitive sensing element to convert the measured pressure into an electrical output with a certain relationship. It is characterized by low input energy, high dynamic response, small natural effects, and good environmental adaptability. It generally uses a round metal film or metal-plated film as an electrode of the capacitor. When the membrane is deformed by pressure, the capacitance formed between the membrane and the fixed electrode changes. Through the measuring circuit, the electrical signal with a certain relationship with the voltage can be output. Capacitive pressure sensor is a capacitive sensor with variable pole distance. It can be divided into single capacitive pressure sensor and differential capacitive pressure sensor.

Read more about: What is the capacitive pressure transducer?

SMT3151 TGP-Gauge Pressure Transmitter / Transducer is a diffusion silicon pressure transmitter. The working principle of the diffused silicon pressure sensor is based on the piezoresistive effect. Using the principle of piezoresistive effect, the pressure of the measured medium directly acts on the diaphragm of the sensor (stainless steel or ceramic). Make the diaphragm produce a slight displacement proportional to the pressure of the medium. To change the resistance value of the sensor. Use electronic circuits to detect this change. And convert and output a standard measurement signal corresponding to this pressure.

3151 gage pressure transmitter

Gauge vs Absolute Pressure Sensor

In terms of pressure type, pressure sensors can be divided into gauge pressure, absolute pressure, and negative pressure.

Absolute pressure: Absolute pressure for short, is the pressure calculated from the absolute zero pressure or the vacuum starting point.

Gage pressure: refers to the pressure calculated from the atmospheric pressure of a specific place at a specific time as a starting point. Atmospheric pressure at the same location will change slightly.

Vacuum: When the measured absolute pressure is less than atmospheric pressure, the difference between the measured absolute pressure and absolute vacuum.

Negative pressure: when the measured absolute pressure is less than atmospheric pressure, the difference between the current atmospheric pressure and the measured absolute pressure, referred to as negative pressure.

The formula for the relationship between absolute pressure, gauge pressure, and atmospheric pressure: absolute pressure = gauge pressure + atmospheric pressure.

Therefore, when selecting a pressure sensor, it is generally necessary to clearly indicate the pressure type of the pressure sensor,

Gauge vs Absolute Pressure Sensor

  1. Gauge pressure and absolute pressure are based on different measurement reference points. The reference point for gauge pressure measurement is the local atmospheric pressure. Absolute pressure is the absolute vacuum zero. Absolute pressure sensors cannot replace gauge pressure sensors.
  2. In layman’s terms. When your measured object uses atmospheric pressure as the reference point, and only has the inflation action, select the gauge pressure type. When your measured object takes absolute vacuum zero as the reference point, and there are inflation and inhalation actions, it is often the absolute pressure type.
  3. The two principles of gauge pressure and absolute pressure sensor are different! Cannot be used instead!

Technical Support

Cryogenic Pressure Transducers

Cryogenic pressure transducer for low temperature pressure measurement.  -196℃~+125℃、-260℃/-350c(especial). Sino-Inst offers a variety of Pressure Sensors for…

Sino-Instrument Gauge Pressure Transmitters, made in China, are high-performance cost-effective devices, used where long term accuracy and reliability is a priority.

SI-3151GP Advanced Transmitter Gauge Pressure Transmitters, are used to measure the pressure of gases, liquids, and steam, as well as to measure tank pressure and fluid levels.
Sino-Instrument 1151 Gauge Pressure Transmitters are high-performance cost effective devices used, where long term accuracy and reliability is a priority.
We also offer Gauge Pressure Transmitter SMT3151 TGP, for the process, oil and gas industry.

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More Featured Products:

SI-EP489 Explosion Proof Pressure Transmitter

Explosion Proof Pressure transmitter refers to a pressure sensor with explosion-proof or intrinsically safe housing. Suitable for hazardous and explosive areas.

Explosion Proof Pressure transmitter, or explosion-proof pressure transducer, with the explosion-proof enclosure. For applications in hazardous areas. Class I, Division 1. Flameproof ExdIIBT5Gb; Intrinsically safe ExiaIICT4/T5/T6Ga.
SIEP489 has flexible pressure calibration, push-button configuration, and programmable using HART® Communication. All our electronic pressure transducers can be offered with Explosion-proof. Select explosion-proof pressure transmitters with Ex d certification and 4-20mA output signals for installation.

Sino-Inst offers a variety of Explosion-proof pressure sensors for industrial pressure measurement. If you have any questions, please contact our sales engineers.

Features of Explosion Proof Pressure Transmitter

  • FM approved as “explosion-proof” for class I, div. 1 hazardous areas
  • Available with EXD approval “flameproof enclosure” for II 2 G Ex d II C
  • Current or voltage output
  • Designed for harsh ambient conditions
  • Low-power version available as an option

Specifications of SIEP489 explosion-proof pressure transmitter:

Standard range
Pressure typeGauge pressure, absolute pressure, sealing pressure
Pressure range (bar)1 1.6 2.5 4 6 10 16 25 40 60 100 160 200 250 300 400 500 600 750 1000 1500
Pressure range (psi)15 30 50 75 100 200 300 500 750 1K 1.5K 3K 5K 10K 12K 15K 25K
Technical Specifications
Accuracy±0.3 %FS    ±0.5 %FS
Long-term stability (1 year)±0.25 %FS
Response frequency (-3DB)3.2kHz
Temperature compensation-20~+85℃
Storage temperature-40~+125℃
Load ResistanceVoltage output: RL > 100KΩ, current output: RL≤ (supply voltage-9V) / 20mA
Overload pressure150% FS (Range < 6Bar) 300% FS (Range≥6Bar)
Destruction pressure200% FS (Range < 6Bar) 500% FS (Range≥6Bar, limit 10000Bar)
Mechanical vibration±20g
Shock (11mS)100g
Protection levelIP65
material17-4PH (Range≥6Bar) 304 or 316L (Range <6Bar)
Electrical connectionsDirect lead
Pressure interfaceM20X1.5   G1 / 4       NPT1 / 4 (others can be customized)
Explosion-proof gradeExd II CT6 Gb
Signal output4~20 mA0.5 ~ 4.5VDC (proportional output)0.5~4.5VDC0~5VDC0~10VDCRS485RS232
Signal line specifications2 Wire3 Wire3 Wire3 Wire3 Wire4 Wire4 Wire
Supply voltage9~30VDC5VDC9~30VDC9~30VDC15~30VDC9~30VDC9~30VDC

Read more about: What Is the Difference Between Class 1 Div 1 and Class 1 Div 2 ?

Explosion proof pressure transmitter drawing

Applications of explosion proof pressure transmitter

Oil & Gas equipment needs a pressure transducer, that is reliable and able to withstand extreme environmental and pressure conditions.

  • Borehole monitoring
  • Oil Field Equipment
  • Refineries and petrochemical industry
  • Drilling platforms and pipelines
  • Upstream Oil and Gas Production
  • Natural Gas Compression and Transfer Control
  • Alternative Energy     
  • Industrial and OEM Applications

We can provide maintenance, calibration and other services of the same type of products. Such as WIKA, Rosemount pressure transmitter.

Contact us now to see how we can help you with a pressure gauge solution that fits your exact needs.

Know More About Explosion proof pressure transmitter

Explosion-proof pressure transmitters are available in a wide range of specifications,
easy to install and use, safe and explosion-proof.
They can be widely used in petrochemical, electric power, metallurgy, pharmaceutical, food processing, and other industries.

Products comply with the “IEC” standard, and explosion-proof pressure transmitters are internationally renowned.

The company’s high-precision, high-stability pressure sensor components,
through high-reliability amplifier circuit and precise temperature compensation,
convert the absolute or gauge pressure of the measured medium into 4~20mA, 0~5VDC, 0~10VDC, and 1~5VDC. Such as standard electrical signals.

High-quality sensors hermetically sealed soldering technology
and a complete assembly process ensures excellent quality and performance.
The product is available in a variety of interface styles.
And a variety of lead styles to best meet customer needs.
And is suitable for use with a variety of measurement and control equipment.

Explosion proof pressure transmitter working principle

The explosion-proof pressure transmitter consists of an integrated intelligent sensor and peripheral circuits.

The sensor part is composed of a pressure sensor, a signal modulation circuit, a dedicated digital processing chip, a temperature sensor, and data memory, and the peripheral electronic circuit part is composed of an LCD display, function keys, and an EMC circuit.

The pressure signal is converted into an electrical signal by the pressure sensor. And the electrical signal is modulated. And sent to a dedicated digital processing chip for data processing.
And then converted into a 4~20 mA output signal corresponding to the pressure signal.
And the HART digital signal is superimposed on the current signal for communication.

Extended reading: How to calibrate HART pressure transmitters

Potentially explosive environment.

Such as flammable gas, dust environment, oil refinery, petrochemical plant, gas station, gas station, etc., explosive gas environment.

Under atmospheric conditions, a mixture of combustible substances in the form of gas, steam or mist, and air. After being ignited in the mixture, the combustion will spread throughout the environment of the unburned mixture.

Such as CH4, C2H2, C2H4, NH3, CO, C2H5OH, and other explosion-proof electrical equipment.

Read more about Steam pressure transmitter-Pressure measure on steam pipeline 

Intrinsically safe VS explosion-proof

The explosion-proof of the current pressure transmitter: mainly two forms of isolation explosion-proof and intrinsically safe explosion-proof.

Intrinsically safe explosion-proof:

“i” (Intrinsically safe electrical equipment and related equipment) Intrinsically safe circuits, circuits that cannot ignite the specified explosive gas or steam under the specified test conditions, under the specified test conditions, the electric sparks and thermal effects generated under the specified fault state . Intrinsically safe electrical equipment: All circuits are intrinsically safe electrical equipment.

Example: Intrinsic Safety: Ex ia II BT4

Flameproof:

It refers to the electrical equipment that encloses the components that can ignite the explosive mixture in a shell, and the shell can withstand the explosive pressure of the internal explosive mixture and prevent the explosion of the surrounding explosive mixture.

For example: Flameproof: Ex d II CT6

Ex(ia)ⅡC T6:

SignSymbolMeaning
Explosion-proof declarationExMeet certain explosion-proof standards, such as my country’s national standards
Explosion-proof methodiaAdopt ia-level intrinsically safe explosion-proof method, can be installed in О area
Gas categoryIl cIt is allowed to involve IIC explosive gas
Temperature groupT6The surface temperature of the instrument does not exceed 85℃

Ex(ia)ⅡC:

SignSymbolMeaning
Explosion-proof declarationExCompliance with European explosion-proof standards
Explosion-proof methodiaAdopt ia-level intrinsically safe explosion-proof method, can be installed in О area
Gas categoryll cIt is allowed to involve explosive gas of IIc

Technical Support

Explosion-proof differential pressure transmitter

Explosion-proof differential pressure transmitter is used to measure the liquid level, flow rate and pressure of liquid, gas or steam under high working pressure environment. Then converted into 4 ~ 20mA DC signal output. Intelligent type can communicate with HART Communicator.

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Steam pressure transmitter

High Temperature Pressure Transducer/Transmitter for measuring pressure in hot environments. Liquids or gases up to 850 ° C. Such as steam, food processing & engine monitoring.

Application of high temperature pressure transmitter in steam pipeline.

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Water pressure transmitter

Liquid level sensors also called a water pressure sensor, or water pressure transducer. SI-10 liquid pressure sensor uses waterproof device to achieve IP68 waterproof rating. Like: water pipe pressure, oil pressure for pipe or tank.SI-10 liquid pressure sensor is a piezoresistive silicon pressure sensor. 

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Natural gas pressure transducer

Gas pressure sensor for industrial gas pressure monitoring. Pagoda gas nozzle Φ8. Such SI-503K Pagoda Joint Gas Pressure sensor uses stainless steel as a whole. High-precision strain gage and advanced technology. It has high sensitivity, stable performance and good impact resistance.

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Sino-Inst offers over 20 Explosion Proof Pressure Transmitters. A wide variety of  Pressure sensors options are available to you. Such as free samples, paid samples. 

Sino-Instrument is a globally recognized manufacturer of Pressure sensors, located in China. Sino-Instrument sells through a mature distribution network that reaches all 30 countries worldwide. 

Pressure sensors products are most popular in Europe, Southeast Asia, and Mid East. You can ensure product safety by selecting from certified suppliers. With ISO9001, ISO14001 certification.

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SMT3151 Remote Diaphragm Seal Pressure Transmitter

Remote seal pressure transmitter, with capillary and diaphragm seal, remote mount. Diaphragm seal systems protect pressure transmitters from hot, viscous, contaminated or corrosive media.

Remote Diaphragm seal pressure transmitter with capillary is used as a level transmitter. Diaphragm Seals also called chemical seals, are used in applications where pressure sensor requires isolation from the process media. These applications are corrosive, high temperature, clogged. Or must sanitary fluids to remain in the pipeline or container. The pressure of the liquid in the process does not affect the pressure sensor. Instead, it is applied to the remote seal. And through the capillary, hydraulic pressure is transmitted to the pressure sensor. Installing and filling the diaphragm seal, the impact on instrument performance will be minimized.

Sino-Inst also offers repair, refurbishment or replacement of used transmitters with remote seals.

Features of Remote Diaphragm Seal Pressure Transmitter

Protect pressure sensor

The remote transmission diaphragm can protect the transmitter diaphragm from corrosive, aggressive or extreme temperature.

Various sealing diaphragms are available

Sino-Inst can provide a suitable sealing diaphragm according to your measurement requirements. For example, remote threaded seal, flush flanged type seals, remote flange seal-RTJ gasket surface, extended flanged seal, etc.

Suitable for special environments.

Such as:
High / low temperature fluids;
Highly corrosive / high viscosity fluids;
Toxic fluids;
The fluids containing suspended solids which are deposited in the impulse piping and may cause clogging.

Specifications of Remote Diaphragm Seal Pressure Transmitter

 Measurement parameters: pressure, liquid level
 Measuring range: lower limit: -100% URL (continuously adjustable);
upper limit: to + 100% URL (continuously adjustable)
 Output: two-wire system, 4-20mADC + HART output, digital communication; output signal limit: Imin = 3.9mA, Imax = 20.5mA
 Alarm current:①Low report mode (minimum): 3.7mA
②High report mode (maximum): 21mA
③No report mode (hold): keep the effective current value before the fault
④Alarm current standard setting: high report mode
 Response time: the damping constant of the amplifier part is 0.1s; the time constant of the sensor and the remote flange is 0.2-6s, which depends on the range of the sensor, the range ratio, the length of the capillary, and the viscosity of the filling fluid The additional adjustable time constant is: 0.1-60s.
 Ambient temperature: minimum: depends on the filling liquid; maximum: 85 ℃; with liquid crystal display, fluorine rubber sealing ring is -20 ~ +65 ℃
 Storage temperature / transport temperature: minimum: depends on filling liquid; maximum: 85 ℃
 Relative humidity: 0-100%
 Anti-shock: acceleration: 50kg; duration 11ms
 Anti-vibration: 2g to 500Hz
 Process medium temperature limit: medium temperature: -20 ~ 400 ℃
 Pressure limit of transmitter body: vacuum to maximum pressure
 Rated pressure of remote flange: ANSI standard: 150psi-600psi; DIN standard: PN1.6MPa-PN10MPa
 Warm-up time: <15s
 Explosion-proof performance: NEPSI explosion-proof license: ExdⅡCT6; NEPSI intrinsically safe license: ExiaⅡCT4; allowable temperature is -40 ~ + 65 ℃
 Power and load conditions:① The power supply voltage is DC24V, R≤ (Us-12) / Imax kΩ, where Imax = 23mA
②Max power supply voltage: 42VDC
③Minimum power supply voltage: 12VDC, 15VDC (backlit LCD display)
④Digital communication load range: 250-600Ω
 Electrical connection: M20 × 1.5 cable sealing buckle, the terminal is suitable for 0.5-2.5mm2 wire
 Process connection: The remote flange meets ANSI standard or DIN standard. Can be installed directly, please refer to the dimension drawing for flange size
 Material: Measuring capsule: stainless steel 316L; diaphragm: stainless steel 316L, Hastelloy C, tantalum
 Process connection: stainless steel 316
 Filling fluid: silicone oil, high temperature silicone oil, ultra high temperature silicone oil, vegetable oil
 Pressure transmitter shell: aluminum alloy material, epoxy resin on the surface
 Shell sealing ring: NBR
 Nameplate: Stainless steel 304
 Weight:DN50 / 2 inches about 7-10kg; DN80 / 3 inches about 8-11kg; DN100 / 4 inches about 9-12kg
 Shell protection grade: IP67

Read more What is a diaphragm seal?

Types of SMT3151 Remote Diaphragm Seal System Pressure Transmitters

3151T flange type remote pressure transmitter

The selection is as follows:
3151TGP4SF00S1M4B4 0~40kPa
1199FFW A50AADL03H00

On behalf of the 3151TGP base table plus an American standard 2”150LB flange type remote transmission device, the capillary length is 3 meters.

3151T flat remote pressure transmitter

The selection is as follows:
3151TGP4SF00S1M4B4 0~40kPa
1199PFWA50AADL03H00

On behalf of the 3151TGP base table plus an American standard 2”150LB flat remote transmission device, the capillary length is 3 meters.

3151T type insert barrel remote pressure transmitter

The selection is as follows:
3151TGP4SF00S1M4B4 0~40kPa
1199EFWA50AABDL03H00

On behalf of the 3151TGP base table plus an American standard 2”150LB plug-in remote transmission device, the capillary length is 3 meters, the insertion barrel length is 100mm.

3151T threaded remote pressure transmitter

The selection is as follows:
3151TGP7SF00S1M4B4 0~1000kPa
1199RTWA1AADL03H00

On behalf of the 3151TGP base table plus a threaded connection remote transmission device, capillary length of 3 meters, user connection thread specifications 1/2NPT-14.

3151T type three clamp type remote pressure transmitter

The selection is as follows:
3151TGP5SF00S1M4B4 0~100kPa
1199SCWA1A0DL03H00

On behalf of the 3151TGP base table plus a three-clamp type remote transmission device, the capillary length is 3 meters, the user connection clamp specification is 1 1/2 inch.

3151GP/DP flange type remote pressure transmitter

The selection is as follows:
3151GP4SF22S1M4B3 0~40kPa
1199FFW A50AADL03H00

On behalf of the 3151GP base table plus an American standard 2”150LB flange type remote transmission device, the capillary length is 3 meters.

3151GP/DP flat remote pressure transmitter

The selection is as follows:
3151GP4SF22S1M4B3 0~40kPa
1199PFWA50AADL03H00

On behalf of the 3151GP base table plus an American standard 2”150LB flat remote transmission device, the capillary length is 3 meters.

3151GP/DP type insert barrel remote pressure transmitter

The selection is as follows:
3151GP4SF22S1M4B3 0~40kPabr>
1199EFWA50AABDL03H00

On behalf of the 3151GP base table plus an American standard 2”150LB plug-in remote transmission device, the capillary length is 3 meters, the insertion barrel length is 100mm.

3151GP/DP type threaded remote pressure transmitter

The selection is as follows:
3151GP7SF22S1M4B3 0~1000kPa
1199RTWA1AADL03H00

On behalf of the 3151GP base table plus a threaded connection remote transmission device, capillary length of 3 meters, user connection thread specifications 1/2NPT-14 specific size,

3151GP/DP type three clamp type remote pressure transmitter

The selection is as follows:
3151TGP5SF22S1M4B3 0~100kPa
1199SCWA1A0DL03H00

On behalf of the 3151GP base table plus a three-clamp type remote transmission device, the capillary length is 3 meters, the user connection clamp specification is 1 1/2 inch.

Diaphragm Seal System

Remote Diaphragm seal pressure transmitter, is the capillary type pressure transmitter. This type pressure transmitter, assembling diaphragm seals to field transmitters for the purpose of measuring pressure, differential pressure, level, and flow.

Diaphragm seals are used to prevent process medium from entering into the pressure-sensing assembly of the Differential pressure, Gauge pressure, or Absolute pressure transmitter.

Applications which is suitable for diaphragm seal system

  • For measuring the liquid level, density, flow and pressure of ;
  • high/low-temperature fluids;
  • highly corrosive/high viscosity fluids ;
  • the fluids which may cause clogging of impulse piping in the low temperature ;
  • toxic fluids;
  • the fluids containing suspended solids, which are deposited in the impulse piping and may cause clogging.
How do diaphragm seals work?

You may like: Diaphragm pressure gauge

How do diaphragm seals work?

Basically, diaphragm seals are used in all pressure measurement processes to avoid direct contact between the measuring instrument and the medium during this process. In addition, if the measuring point cannot be installed or read because the measuring point is located in a hard-to-reach location, a diaphragm seal can also be used. In both cases, the applied pressure is transferred to the measuring instrument through the system fill fluid in the diaphragm seal housing.
The diaphragm of the seal can be made of different materials, such as stainless steel, Hastelloy, Monel or tantalum. In addition, coatings with ECTFE, PFA or gold can also be used.

We can provide the best diaphragm seal design, materials, system fill fluid and accessories for each application. The combined configuration of the pressure measuring instrument and the diaphragm seal is mainly determined by the special application conditions of the diaphragm sealing system.

How does a diaphragm pressure sensor work?

When the diaphragm seal pressure transmitter is working, the high and low pressure side isolation diaphragms and the filling liquid transfer the process pressure to the center filling liquid. The filling fluid in the center transmits the pressure to the sensing diaphragm in the center of the δ-chamber sensor. The sensing diaphragm is a tensioned elastic element, and its displacement changes with the differential pressure. For GP gauge pressure transmitters, the atmospheric pressure is applied to the low-pressure side of the sensing diaphragm. AP absolute pressure transmitter, the low pressure side always maintains a reference pressure. The maximum displacement of the sensing diaphragm is 0.004 inches (0.10 mm). The displacement is proportional to the pressure. The two capacitance fixed plates of the measuring diaphragm are linearly converted into a 2-wire current, voltage or digital HART output signal of 4-20mADC by the amplifying circuit.

What is a diaphragm seal?

Diaphragm seals, also known as chemical seals or remote seals, are used for pressure measurements when the process medium should not come into contact with the pressurised parts of the measuring instrument.

A diaphragm seal has two primary tasks:

  1. Separation of the measuring instrument from the process medium
  2. Transfer of the pressure to the measuring instrument

Extended reading: SI-703 Flush Diaphragm Pressure Sensor

What is remote seal?

The remote seal is used to prevent the medium in the pipeline from directly entering the pressure sensor assembly in the pressure transmitter. It is connected to the transmitter by a capillary filled with fluid. As a result, they’re often used in refining, petrochemical, and chemical plants.

Applicaitons of diaphragm seal

Typical applications where a diaphragm seal provides a cost-effective solution, to protecting the pressure instrument are:

  • In applications where the process fluid is corrosive;
  • In applications where the process fluid has a high viscosity,
    is comprised of slurries, sludge or other material that can actually coat,
    or damage a traditional pressure measuring device;
  • In applications where the process fluid can freeze or polymerize,
    thus causing a condition that might lead to the instrument becoming immobilized,
    or incapable of transmitting an accurate pressure measurement or signal.

The process side of the seal is isolated by a flexible diaphragm. The internal space between this diaphragm and pressure measuring sensor is filled with a system fill fluid. The pressure is transmitted from the measured medium, by the elastic diaphragm into the fluid. And from there to the measuring element, i.e. to the pressure measuring instrument or the transmitter.

Often, between the diaphragm seal and pressure measuring instrument, a capillary is connected. Capillary can eliminate or to minimize temperature effects from the hot fluid to the measuring instrument.

A Remote seal is mounted to the process by threaded, flanged, in-line, sanitary, or other connections. Usually, the fittings consist of T-pieces which are integrated into a pipeline, or of welding sockets which are welded to a pipeline, the process reactor or a tank.

This diaphragm seal type offers the advantage, that the “contact surface” between pressure medium and the diaphragm is relatively large. Thus ensuring accurate pressure measurement, especially for very low pressures (< 600 mbar).

Although standard remote seal bodies and diaphragms, are made of stainless steel, a variety of materials, from carbon steel to Hastelloy® C-276, are available to meet the demand of most applications.

A remote seal from Sino-Instrument can operate in pressure applications from 10″ Hg to 20,000 psi, and media temperatures between -130°F and 752°F. We can try to Learn more about the functionality, areas of application and advantages of a diaphragm seal in the following WIKA video.

Extended reading: Flat Pressure Sensor for High Viscosity Fluids

Diaphragm type pressure transmitter

https://www.drurylandetheatre.com/diaphragm-sealed-differential-pressure-transmitters-for-sale/

Data sheet of SMT3151 Diaphragm Seal Pressure transmitters

Diaphragm seal pressure transmitter installation

  1. The remote pressure transmitter without capillary can be directly installed through the remote flange. The position deviation will produce a correctable zero offset
  2. The electronic watch case can rotate 360 degrees at the maximum. The positioning screw can fix it at any position.
  3. Single-crystal silicon remote flange is connected with the matching flange conforming to ANSI / DIN standard. The matching flange should be equipped with soft gasket and fixed bolts and nuts. The user can choose to install bolts and nuts.
  4. For the remote transmission pressure transmitter with capillary, if the remote transmission sealing device is lower than the transmitter body, the maximum height drop between the remote transmission sealing device and the transmitter body should be less than 5m. When the working pressure is lower than 100kPa absolute pressure, the transmitter body must be lower than the remote transmission sealing device.
  5. The minimum bending radius of the capillary is 75mm, winding is strictly prohibited

Q&A

Parameters that determine the design of a remote seal transmitter

Location of the transmitter (indoor versus outdoor).
Temperatures (process and ambient).
Exposure to vacuum.
Pressure (operating and maximum).
Length of capillary.
Type of seal desired.
Process connection, material of construction and similar considerations.
Installation requirements.
Measurement span.

When are threaded connections used with diaphragm seals?

The combinations of diaphragm seals with threaded connection can be used for processes with extreme temperatures and with aggressive, adhesive, corrosive, environmentally hazardous or toxic media.

Why are there different system fill fluids with diaphragm seals?

In selecting the system fill fluid for diaphragm seals, factors such as compatibility (physiologically harmless) and also temperature and pressure conditions at the measurement location are of crucial importance. Depending on the system fill fluid, the appropriate minimum and maximum operating temperature range must be observed.

How are the diaphragm seals connected?

The diaphragm seals are available with female or male thread in their basic design. Due to the wide variety of available process connections they can be mounted to many different connections without any problems. Generally these connections are T-pieces which are integrated into a pipeline or welded to a pipeline by means of a welding socket.

Sino-Instrument offers SMT3151 Diaphragm Seal Pressure transmitter. Work the same as Wika diaphragm seal pressure transmitter; diaphragm seal pressure transmitter Rosemount; Yokogawa diaphragm seal pressure transmitter.

Sino-Instrument are diaphragm seal pressure transmitters manufacturer. We can offer you automated instruments from China, With best price.

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3051HP Hydrostatic Pressure Transmitter

What is hydrostatic pressure transmitter?

Hydrostatic Pressure Transmitters is an instrument that measures the hydrostatic pressure or differential pressure exerted by a hydrostatic head.

Feel the measured pressure through the remote transmission device installed on the pipeline or container. The pressure is transmitted to the main body of the transmitter through the filling silicone oil (or other liquid) in the capillary tube. Then there is the delta chamber and the amplifier circuit board in the main body of the transmitter. Convert into 4-20mA DC signal output. HP Smart can communicate with a HART handheld communicator. Use it to set, monitor, or form an on-site monitoring system with the host computer.

Hydrostatic Pressure Transmitters are often used to measure the level, flow, and pressure of liquids, gases, or steam under high working pressure environments.

Features of Hydrostatic Pressure Transmitter

The Hydrostatic pressure transmitter is used to measure the liquid level, flow, and pressure of the liquid, gas or steam under high working pressure, and then convert to 4~20mA DC signal output.

The Hydrostatic pressure transmitter is used to measure the liquid level, flow, and pressure of the liquid, gas or steam under high working pressure, and then convert to 4~20mA DC signal output.

  • The high hydrostatic pressure transmitter can measure differential pressure below 32MPa hydrostatic pressure.
  • With 32MPa working pressure and overload protection.
  • Ensuring reliable application of the transmitter in Hydrostatic pressure systems.

Read more about: Steam pressure transmitter-Pressure measure on steam pipeline 

Specifications of Hydrostatic Pressure Transmitter

Measure Range of Hydrostatic pressure sensor:

Differential pressure: 0-1.3-6790KPa
Hydrostatic pressure: 32MPa

  • Use object: liquid, gas or steam
  • Output signal: 4-20mA dc. Output superimposed HART protocol digital signal (two-wire system)
  • Power source: external power supply 24V dc. Power supply range 12V ~ 45V
  • Installation in dangerous places:
    • Flameproof  ExdIIBT5Gb;(explosion-proof certificate no. :CE16.1163)
    • Intrinsically safe ExiaIICT4/T5/T6Ga;(explosion-proof certificate no. : CE15.2354X) ;
  • Accuracy: ± 0.1%, ±0.2%
  • Stability: ±0.25%/6 months of maximum range
ModelTransmitter type
HPAbsolute pressure transmitter
CodeScale range
20-0.10~3.5kPa(0-10~350mmH2O)
30-0.8~8.0kPa(0-80~800mmH2O)
40-4.0~40kPa(0-400~4000mmH2O)
50-20~200kPa(0-2000~20000mmH2O)
60-70~700kPa(0-0.7~7kgf/cm2)
70-210~2100kPa(0-2.1~21kgf/cm2)
80-700~7000kPa(0-7.0~70kgf/cm2)
90-2.1~21MPa(0-21~210kgf/cm2)
00-4.1~41MPa(0-41~4100kgf/cm2)
CodeOutput form
ELinear output 4-20mAdc
SFLinear/square root output 4-20mAdc +HART signal,,Full function buttons on site
FMODBUS-485 signal
CodeStructural materials
Flange connectorExhaust/Drain valveIsolation diaphragmFilling liquid
22316 Stainless steel316 Stainless steel316 Stainless steelSilicone oil
23316 Stainless steel316 Stainless steelHastelloy CSilicone oil
24316 Stainless steel316 Stainless steelMonelSilicone oil
25316 Stainless steel316 Stainless steelTantalumSilicone oil
33Hastelloy CHastelloy CHastelloy CSilicone oil
35Hastelloy CHastelloy CTantalumSilicone oil
44MonelMonelMonelSilicone oil
CodeShell materialConduit inlet dimensions
ALow copper aluminum alloy polyurethane coatingM20×1.5
BLow copper aluminum alloy polyurethane coating1/2-14 NPT
CStainless steelM20×1.5
DStainless steel1/2-14 NPT
CodePressure connection
L11/4NPT-18 Internal thread(excluding waist joint standard)
L21/2NPT-14 Internal thread
L3M20×1.5 External thread
CodeOptional parts
M4LCD multi-power digital display head
B1Pipe bending bracket
B2Plate bending bracket
B3Pipe mounting bracket
C02M20×1.5 nut and Φ 14 pressure short tube
C121/2NPT-14 external thread and Φ14 pressure short tube
C221/4NPT-18 external thread and Φ14 pressure short tube
C321/4NPT-18 to M20×1.5 external thread
C421/2NPT-14 to M20×1.5 external thread
C431/2NPT-14 to 1/4NPT-18 internal thread
C441/2NPT-14 to 1/2NPT-14 external thread
C451/2NPT-14 to G1/2 external thread
D1The side discharge valve is on the upper part
D2The side discharge valve is on the upper part
X1Oil ban
DaFlameproof ExdIIBT5Gb;(explosion-proof certificate no. : CE16.1163)
FaIntrinsically safe ExiaIICT4/T5/T6Ga;(explosion-proof certificate no. : CE15.2354X)

Hydrostatic Pressure Transmitter Applications

  • Viscous medium at high temperature
  • Crystallizable medium
  • Precipitating medium with solid particles or suspended matter
  • Strong corrosive or highly toxic medium
  • It can eliminate the phenomenon that the pressure guiding tube leaks and pollutes the surrounding environment. It can avoid the instability of the measurement signal when the isolation fluid is used. The tedious work of frequently supplementing the isolation fluid is required.
  • Continuous and accurate measurement of interface and density
  • The remote transmission device can avoid the mixing of different instantaneous media. So that the measurement result truly reflects the actual situation of the process change.
  • Occasions requiring high hygiene and cleanliness
  • For example, in the production of food, beverage and pharmaceutical industries, it is not only required that the parts of the transmitter contacting the medium meet the hygienic standards. It should also be easy to wash. To prevent cross-contamination of different batches of media.

Extended reading: Silicon Pressure Sensor

Hydrostatic Pressure

Hydrostatic pressure is the pressure generated by the weight of the liquid above the measurement point when the liquid is stationary. The height of the liquid column with uniform density is proportional to the hydrostatic pressure. As the weight of the fluid exerting downward force from above increases, the hydrostatic pressure increases in proportion to the depth measured from the surface.

Read more about: Differences! Static pressure vs dynamic pressure vs total pressure

If the fluid is inside the container, the depth of the object placed in the fluid can be measured.
The hydrostatic characteristics of a liquid are not constant, and the main factors affecting it are the density and local gravity of the liquid. In order to determine the hydrostatic pressure of a particular liquid, both quantities need to be known.

The deeper an object is placed in a fluid, the greater the pressure it bears. This is because the weight of the fluid is higher than its weight. Due to the weight of the fluid, the denser the fluid above it, the greater the pressure on the submerged object.

Measuring principle

The pressure in the liquid increases as the filling height increases. The hydrostatic pressure is transmitted to the measuring unit through the stainless steel diaphragm. Bubbling, accumulation of liquids, fluctuating electrical characteristics, and container design will not affect the measured value.

Extended reading: What is flush diaphragm?

Formula for calculating hydrostatic pressure

The formula for calculating the hydrostatic pressure of a column of liquid is:

Phyd = h.ρ.g

Prel = h.ρ.g

Pabs = h.ρ.g + Patm

Phyd = Hydrostatic Pressure (Pa)
Prel = Relative Pressure (Pa)
Pabs = Absolute Pressure (Pa)
Patm = Atmospheric Pressure (Pa)
h = Liquid Height (m)
ρ = Liquid Density (kg/m3)
g = Local Gravity (m/s2)

The above calculation formula is also the working principle of hydrostatic liquid level sensor.

The hydrostatic pressure sensor measures the hydrostatic pressure applied by the hydrostatic head. Output 4-20mA.
Use a hydrostatic pressure transmitter to measure the storage tank and pump inlet. And other applications where hydrostatic pressure is used to determine the liquid level.

Hydrostatic Pressure Sensor/Transmitter can also be used with paperless recorder.

Hydrostatic Level Sensor measures the hydrostatic pressure by the submersible pressure sensor. The static pressure of the liquid is proportional to the height of the liquid. Then the static pressure was converted into an electrical signal. Convert to analog signal output or 4-20mADC. With digital display. For water level measurement, hydrostatic level sensor is a low cost type. Different types of measuring cells are used in level measurement based on the hydrostatic principle.

Lightning protection, anti-corrosion, explosion-proof optional. IP68 is optional.

Read more about: Hydrostatic Level Sensor

The basic working principle of Hydrostatic Level Sensor is static pressure level measurement.

In liquid, the pressure generated at a certain depth is generated by the weight of the medium itself above the measurement point. It is proportional to the density of the medium and the local acceleration of gravity.

The formula P = ρgh reflects the proportional relationship between them.

Where P = pressure, ρ = medium density, g = gravity acceleration, h = depth of measurement point.

Therefore, the physical quantity measured by the input liquid level gauge is actually pressure. It can be understood by the calibration unit mH2O of the input level gauge. The actual liquid level must be obtained by conversion after knowing the two parameters of density and gravity acceleration. In the industrial field, such conversion is usually performed by a secondary instrument or PLC.

The Hydrostatic Level Sensor mainly measures corrosive liquids such as hydrochloric acid, hydrogen peroxide, etc. Or chemical and electroplating wastewater. Mainly used in measuring corrosive media. It has the advantages of strong corrosion resistance and stable performance.

Extended reading: Static pressure vs dynamic pressure vs total pressure

There are various methods and techniques for measuring fluid level using hydrostatic pressure sensors. Depending on the installation, they all have advantages and disadvantages. Hydrostatic pressure measurement is an accurate and convenient technique for determining fluid height or volume.

Let’s take a look at each according to the installation location of the hydrostatic pressure sensor.

Externally mounted type

Image source: https://www.yourlevelexperts.com/zh-hant/product/hydrostatic-pressure/

The Hydrostatic pressure liquid level sensor can be installed to the outside of the container through threads or flange fittings. If necessary, capillaries can also be used.

Submersible type

Picture source: network picture

If the externally mounted sensor is not available, a submersible pressure sensor can be used. The electrical connection with IP68 rating is suitable for long-term permanent immersion. The electronic equipment of the sensor can be protected from the external environment.

Read more about: [What is and How it Works]Hydrostatic Level Sensor

DP transmitters are Differential Pressure Transmitters. DP transmitter measures the pressure difference between the gas or liquid at both ends of the transmitter. Output 4~20mA, 0~5V. Used for liquid level, density, and pressure of liquid, gas, and steam.

DP transmitters are different from pressure transmitters as they have 2 pressure interfaces. With flanges, capillaries, valves, brackets, throttle devices. Differential pressure transmitters are used to measure the level, density, and flow of liquids, gases, and vapors. Then convert it into 4–20mADC current signal output.

Read more.

pressure transducer often called a pressure transmitter, is a transducer that converts pressure into an analog electrical signal.

Although there are various types of pressure transducers, one of the most common is the strain-gage base transducer.

The conversion of pressure into an electrical signal is achieved by the physical deformation of strain gauges, which are bonded into the diaphragm of the pressure transducer, and wired into a Wheatstone bridge configuration.

Pressure applied to the pressure transducer produces a deflection of the diaphragm, which introduces strain to the gages.

The strain will produce an electrical resistance change proportional to the pressure.

Read more.

Hydrostatic pressure transmitter fault debugging steps:

How to debug the fault of Hydrostatic pressure transmitter

Total Time: 30 minutes

Check the power supply

Check if the power supply of the differential pressure transmitter is reversed, and whether the positive, and negative poles of the power supply are connected correctly.

Measure the power supply

Measure the power supply of the transmitter, whether there is 24V DC voltage. It must ensure that the power supply voltage to the transmitter is ≥12V
(that is, the voltage of the transmitter power input terminal is ≥12V).
If there is no power supply, check whether the circuit is disconnected, whether the instrument is selected incorrectly (input impedance should be ≤250Ω), and so on.

Check the display meter

If the pressure transmitter is equipped with a meter head, it is necessary to check whether the dislay meter is damaged. You can short-circuit the two wires of the meter head first. If it is normal after a short circuited, it means the head is damaged.
If the meter head is damaged, Then you need to change the header.

Check the current

If there is a problem with the differential pressure transmitter, connect the ammeter to the 24V power supply circuit to check if the current is normal.
If it is normal, the transmitter is normal. In this case, check if other instruments in the loop are normal.

Connect the power supply

Connect the power supply to the transmitter power input terminal, and connect the power cable to the power supply wiring port.
If you still have any question with the selection, application, and use of pressure transmitters, you can just contact our engineer today.

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Hydrostatic pressure transmitter/sensor measures the level, density, and pressure of liquid, gas, or steam. And then converts it into a 4-20 mA DC signal output. The Hydrostatic pressure transmitter can communicate with the HART communicator intelligently. Use it to set, monitor or form a site monitoring system with the host computer. Use a Hydrostatic pressure sensor to measure tanks, processing vessels, headers, pump inlets and others using hydrostatic pressure to determine the liquid height. SI3051HP Hydrostatic pressure transmitters, with working Hydrostatic pressure up to 32Mpa.

Extended reading: Best Price Ceramic Pressure Sensor

Sino-Inst offers a variety of Hydrostatic Pressure Transmitters for industrial pressure measurement. If you have any questions, please contact our sales engineers.

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SMT3151AP Absolute Pressure Transmitter

Absolute pressure transmitters measure the difference between vacuum and measured pressure. Absolute pressure (AP) transmitter is a measure of the ideal (complete) vacuum.

Absolute pressure transmitters, also known as absolute pressure transducer,
and absolute pressure sensor. Measure absolute pressure relative to full vacuum. In contrast, pressure measured relative to atmosphere is called gauge pressure. All absolute pressure measurements are positive. The readings produced by absolute pressure sensors are not affected by atmosphere. When the pressure corresponds to the ideal vacuum, the absolute pressure transmitter will produce a 4mA output signal.

Sino-Inst offers a variety of pressure senors for industrial pressure measurement. If you have any questions, please contact our sales engineers.

Absolute Pressure Transmitter Features

Direct Mount Pressure-Absolute Pressure Transmitter
  • Sensor Type : Industrial Pressure Transducers
  • Full function buttons on site
  • Pressure ranges: 0 … 1 mbar up to 0 … 600 bar
  • Output/Span 0 – 10 V, 0 – 5 V, 1 – 5 V, 10 mV/V, 4 – 20 mA, HART
  • Pressure Port/Fitting : 1/2 MNPT, 1/4 FNPT, 1/4 MNPT, 1/8 MNPT
  • Operating Temperature Range: -40 – 85 °C [ -40 – 185 °F ]

Extended reading: How to calibrate HART pressure transmitters

Specifications of Absolute Pressure Transmitter

ModelTransmitter type
SI-1301GPPressure transmitter
SI-1301APAbsolute pressure transmitter
CodeScale range
20-0.10~3.5kPa(0-10~350mmH2O)
30-0.8~8.0kPa(0-80~800mmH2O)
40-4.0~40kPa(0-400~4000mmH2O)
50-20~200kPa(0-2000~20000mmH2O)
60-70~700kPa(0-0.7~7kgf/cm2)
70-210~2100kPa(0-2.1~21kgf/cm2)
80-700~7000kPa(0-7.0~70kgf/cm2)
90-2.1~21MPa(0-21~210kgf/cm2)
00-4.1~41MPa(0-41~4100kgf/cm2)
CodeOutput form
ELinear output 4-20mAdc
SFLinear output 4-20mAdc+HART signal,Full function buttons on site
FMODBUS-485 signal
CodePressure connection
L11/4NPT-18 Internal thread (excluding waist joint standard)
L21/2NPT-14 Internal thread
L3M20×1.5 External thread
CodeOptional parts
M4LCD multi – power digital display head
B1Pipe bending bracket
B2Plate bending bracket
B3Pipe mounting bracket
D0The discharge valve is at the end
D1The side discharge valve is on the upper part
D2The side discharge valve is on the upper part
C02M20 x 1.5 nut and Φ 14 pressure short tube
C121/2NPT-14 external thread and Φ14 pressure short tube
C221/4NPT-18 external thread and Φ14 pressure short tube
C321/4NPT-18 to M20×1.5 external thread
C421/2NPT-14 to M20×1.5 external thread
C431/2NPT-14 to 1/4NPT-18 internal thread
C441/2NPT-14 to 1/2NPT-14 external thread
C451/2NPT-14 to G1/2 external thread
X1Oil ban
GdMeasure the gold-plated membrane box
DaFlameproof  ExdIIBT5Gb;(explosion-proof certificate no. : CE16.1163)
FaIntrinsically safe ExiaIICT4 / T5 / T6Ga;(explosion-proof certificate no. : CE15.2354X)
CodeFlange connectorExhaust/Drain valveIsolation diaphragmFilling liquid
22316 Stainless steel316 Stainless steel316 Stainless steelSilicone oil
23316 Stainless steel316 Stainless steelHastelloy CSilicone oil
24316 Stainless steel316 Stainless steelMonelSilicone oil
25316 Stainless steel316 Stainless steelTantalumSilicone oil
33Hastelloy CHastelloy CHastelloy CSilicone oil
35Hastelloy CHastelloy CTantalumSilicone oil
44MonelMonelMonelSilicone oil
CodeShell materialConduit inlet dimensions
ALow copper aluminum alloy polyurethane coatingM20×1.5
BLow copper aluminum alloy polyurethane coating1/2-14 NPT
CStainless steelM20×1.5
DStainless steel1/2-14 NPT

Read more about: Common Units Of Pressure

What is the absolute pressure? 

The pressure acting on the surface of object is called “absolute pressure”. The absolute pressure value starts with absolute vacuum.

The absolute pressure sensor measures the pressure relative to the high vacuum reference. The high vacuum reference is sealed behind its sensing diaphragm. The vacuum must be negligible compared to the pressure to be measured.

Sino-Inst’s absolute pressure sensor provides a pressure range of 1 bar or even 700 mbar. Most electronic pressure sensors measure pressure based on the deformation of the diaphragm.

For Gauge pressure sensors, One side of the diaphragm is exposed to process pressure, while the other side is exposed to ambient. This means that the pressure is actually the difference between the process pressure and atmospheric.

For absolute pressure sensors, the side of the sensor that is not in contact with the pressure medium is exposed to a permanently sealed absolute vacuum chamber. The deformation of the diaphragm is not affected by atmospheric. Because it uses a sealed vacuum as a reference point and zero point.

What is absolute pressure transmitter?

Absolute pressure (AP) transmitter measure relative to perfect (full) vacuum pressure (absolute zero pressure).

Therefore, AP transmitters are not affected by fluctuations in the local atmosphere.

All absolute pressure measurements are positive.
The letter ‘a’ or the abbreviation ‘abs’ in the unit of measure
(i.e., inH₂O(abs) or psia) indicates an absolute pressure measurement.

Any critical storage and delivery (toxic gases) will change due to atmospheric conditions. So these systems must be accurate and use static references. Absolute pressure transmitters are used in applications where the pressure of a gas or liquid is isolated from changes in atmosphere. For example, when testing a sealed pressure vessel for leaks for a long time.

How do absolute pressure sensors work?

The absolute pressure transmitter is mainly composed of two parts. One part is directly connected to the side to be measured. The other side is designed as an absolute vacuum reference chamber. This makes the two compartments form Absolute pressure. When the pressure on both sides is inconsistent, the difference signal will be transmitted through a special transmission line. The computer system in the background can calculate the difference. The pressure value on the measured side is directly displayed.

Applications for Absolute Pressure Sensors

Absolute pressure sensors and absolute pressure gauges are commonly used in industrial high-performance vacuum pumps that require monitoring.

For example, it is used to vacuum package medical products in a clean environment. To ensure that hospitals and doctors are provided with hygienic and bacteria-free delivery.

In the food industry, when the highest possible vacuum is needed to prevent oxygen from degrading perishable food, vacuum packaging can be used, which greatly extends the flavor and shelf life of the product.

For example, in meat packaging, a vacuum that meets the requirements must be generated, so that the longest shelf life can be safely guaranteed.

Pressure sensors affected by the atmosphere cannot monitor the high end of the vacuum.

Applications that require true absolute pressure sensors and gauges can also be found in scientific laboratories, universities, military and aerospace industries.

Applications requiring true absolute pressure sensors and gauges, can also be found in scientific laboratories, universities, the military, and the aviation industry.

Sino-Instrument supplies Direct Mount Pressure / Absolute Pressure Transmitter.

SMT3151 Absolute Pressure Transmitter
SM3151 TAP Pressure-absolute pressure transmitter shape and installation dimensions

Absolute pressure transmitter calibration

  1. First make a 4-20mA fine adjustment. It is used to calibrate the D / A converter inside the transmitter. Because it does not involve sensing components, no external pressure signal source is required.
  2. Do a full fine-tuning again. Make the 4-20mA, digital reading coincide with the actual applied pressure signal. Therefore, a pressure signal source is required.
  3. Finally, re-quantify the range. By adjusting the analog output 4-20mA and the external pressure signal source. Its function is exactly the same as the zero (Z) and range (R) switches on the transmitter shell.

Gauge pressure VS absolute pressure

1. Gauge pressure:

Gage pressure refers to pipeline pressure. It refers to the pressure measured with pressure gauges, vacuum gauges, U-shaped tubes and other instruments. It is also called relative pressure. “Gage pressure” starts from atm.

2. Absolute pressure:

The pressure directly acting on the surface of the container or object is called “absolute pressure”. The absolute pressure value starts with absolute vacuum.

3. Relationship:

Absolute pressure actually refers to the gauge pressure plus the local atm.

Absolute pressure = gauge pressure + 1 atm

If it is in MPa, absolute pressure = gauge pressure + 0.1MPa

Gauge pressure = absolute pressure-atm

Vacuum = atm-absolute pressure

The pressure measured on the basis of absolute vacuum is the absolute pressure. The pressure measured on the basis of atm is the gauge pressure or the degree of vacuum. G behind the pressure indicates gauge pressure, A indicates absolute pressure.

The gauge pressure g = gauge refers to the pressure indication of the pressure gauge on the system. It can also be simply understood as putting a pressure gauge under atm, at which time the pressure gauge displays zero. The gauge pressure at this time is displayed as 0. If the pressure of this gauge pressure rises, the rising value is the gauge pressur

Read more about: Absolute Pressure Vs Gauge Pressure Measuring Instruments

Absolute pressure transmitter VS Gauge pressure transmitter

Absolute pressure transmitter

Absolute pressure transmitter can realize absolute pressure measurement in equipment such as degassing system, distillation tower, evaporator and crystallizer, and allows pressure under 10Mpa. The δ chamber side of the absolute pressure transmitter receives the measured absolute pressure signal. The other side is sealed into a high vacuum reference chamber. Then convert it into 4 ~ 20mA DC signal output.

Gauge pressure transmitter

A gauge pressure transmitter in the general sense is mainly composed of a load cell sensor (also called a pressure sensor), a measurement circuit and a process connection. It can convert the physical pressure parameters such as gas and liquid felt by the load cell sensor into standard electrical signals (such as 4 ~ 20mADC, etc.), and provide secondary indicators such as alarm indicators, recorders, and regulators for measurement and indication. And process regulation.

https://www.drurylandetheatre.com/series-siep489-explosion-proof-pressure-transmitter/

Sino-Inst is Chinese manufacturer of absolute pressure transmitters.

SMT3151ap absolute pressure transmitters, are our mian products, which are widely used in India, US, South Africa, and other countries.

Contact us any time, if you need the quotation or technical support.

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SI2088 High Temperature Pressure Transmitter/Transducer

High Temperature Pressure Transducer/Transmitter for measuring pressure in hot environments. Liquids or gases up to 850 ° C. Such as steam, food processing & engine monitoring.

High Temperature Pressure Transducer/Transmitter works for steam and fluid. Temperature: -30 ℃ ~ 160-350 ℃, customized up to 850 ° C. It is possible to fit a stand off pipe, pigtail or other cooling device to reduce the media temperature. If not, High Temperature Pressure Transducer/Transmitter is the best choice. The pressure is transmitted to the sensor through the heat dissipation structure on the transmitter. The high-precision signal processing circuit is located in the stainless steel housing. The sensor output signal is converted to standard output signal, like 4-20mA.

Sino-Inst is a manufacturer of high temperature pressure transducer in China. Committed to the manufacture, sales and engineering support of high temperature pressure sensors.

Features of SI2088 high-temperature transmitter

Differential, acceleration compensated, piezoelectric pressure sensor for operation temperatures up to 850 ° C.

  • Operating temperature –55 …850 ° C
  • Internally case isolated
  • Differential charge output
  • Highest reliability
  • Not pyroelectric
  • Acceleration compensated
  • ATEX/IECEx certificated
  • CE IECEx and EAC conform

High temperature differential output pressure sensor for measuring lowest pressure fluctuations in a harsh environment up to 850 ° C. For applications in hazardous areas, the sensor is available with intrinsically safe Ex-ia and non-incendive Ex-nA certifications. for Gas Turbine- and Thermoacoustics Applications

Specifications of High Temperature Transducer

Range: 0 ~ 1KPa ~ 10KPa ~ 400KPa, -0.1 ~ 0 ~ 1 ~ 60 (MPa), 0 ~ 10KPa ~ 100MPa
Comprehensive accuracy: 0.25% FS, 0.5% FS
Output signal:4-20mA (2-wire system), 0-5 / 1-5 / 0-10V (3-wire system)
Power supply voltage: 24DCV (9 ~ 36DCV)
Medium temperature: -30 ℃ ~ 160-350 ℃, customized up to 800 ℃.
Ambient temperature: Normal temperature (-20 ~ 85 ℃)
Load resistance: Current output type: maximum 800Ω; voltage output type: greater than 50KΩ
Insulation resistance: Greater than 2000MΩ (100VDC)
Long-term stability: 0.1% FS / year
Vibration effect: In the mechanical vibration frequency 20Hz ~ 1000Hz, the output change is less than 0.1% FS
Electrical interface: Hessman connector (customizable)
Thread connection: M20 × 1.5, etc. Other threads can be designed according to customer requirements
Dimensions: M20 × Φ26.5 × 156
Shell protection: Plug type (IP65); cable type (IP67)
Safety explosion-proof: Ex iaⅡ CT5

Extended reading: High accuracy pressure transducers

Applications of high-temperature transmitter

SI2088 High Temperature Pressure Transmitter / Transducer
Used in the fields of steam, oil, boiler and heat energy exchange. Realize the measurement of liquid, gas and vapor pressure.

Examples of application examples:

  • Industrial field process pressure detection
  • Laboratory pressure calibration system
  • Navigation and Shipbuilding
  • Aviation and aircraft manufacturing
  • Air separation equipment and thermal power unit

Application of high-temperature transmitter

Extended reading: Common Pressure Sensor Applications

Application of high temperature pressure transmitter in steam pipeline

Pure steam pipes have good mechanical properties and thermal insulation properties. Under normal circumstances, it can withstand a high temperature of 120 ° C. It can withstand a high temperature of 180 ° C by modification or in combination with other thermal insulation materials. It is suitable for thermal insulation of various cold and hot water high and low temperature pipelines. The pressure detection in the steam pipeline is very important. And because of the high temperature characteristics in the pipeline. Therefore, it is suitable to use the high temperature pressure transmitter designed by our company for such occasions.

Extended Reading: MEMS Pressure Sensors

In addition, in the steam system, water hammer (Water Hammer) is one of the main hazards causing casualties. Thereby eliminating the hazard of water hammer. This shows that daily pressure monitoring of the pipeline is very important.

Extended reading: High Temperature Flow Meter

Precautions for the correct use of steam pressure transmitters

   1. Prevent the steam pressure transmitter from contacting with corrosive or overheated media;
   2. Prevent dross from depositing in the conduit;
   3. When measuring gas pressure, the pressure port should be opened at the top of the pipeline, and the pressure transmitter should also be installed at the top of the pipeline, so that the accumulated liquid can be easily injected into the process pipeline;
   4. The pressure guiding pipe should be installed in a place with small temperature fluctuation;
   5. When measuring steam or other high-temperature media, a condenser such as a buffer tube (coil) should be connected, and the working temperature of the transmitter should not exceed the limit;
   6. When freezing occurs in winter, the transmitter installed outdoors must take anti-freezing measures to avoid the expansion of the liquid in the pressure port due to the frozen volume, resulting in the loss of the sensor;
   7. When wiring, pass the cable through the waterproof connector or the flexible tube and tighten the sealing nut to prevent the rainwater etc. from leaking into the transmitter housing through the cable.

High Temperature Pressure Transducers vs. Cooling Elements

Generally, the design method is to reduce the temperature near the pressure transmitter by incorporating mechanical cooling components to dissipate heat.

The cooling assembly may be filled with oil and isolated from the process medium by the isolation diaphragm.

Alternatively, the cooling assembly may include a hollow tube. The shape of the hollow tube is designed to increase heat transfer. This allows the process medium that is allowed to pass to be lowered to a much lower temperature.

The cooling element usually relies on the principle of convection heat transfer. This convective heat transfer principle is a mechanism for transferring heat due to the movement of fluid. In contrast, conductive heat transfer is the transfer of energy due to molecular vibration. In addition to cooling elements, convection is also used in many other engineering practices.

The cooling element may be able to reduce the temperature of the medium. This is usually a much cheaper solution than high temperature sensors. It is assumed that the medium density is not greatly affected by temperature changes within the normal operating range. Then this method can keep the pressure unchanged. The cooling element usually works in air and water, but it is not suitable for oily media such as hydraulic oil. High temperature sensors must be used in these applications because the viscosity of this medium is highly temperature dependent.

The cooling element should be made of stainless steel so that most process media have maximum corrosion resistance. The nickel content of the steel is usually 1.25% and the chromium content is 0.65% to 0.8%. The cooling element should withstand a maximum pressure of 5,000 psi at 38 ° C (100.4 ° F) and a maximum pressure of 3500 psi at 400 ° C (752 ° F). It also reduces the liquid process temperature at the sensing element from 260 to 38 ° C (500 to 100.4 ° F).

600 ℃ High Temperature Remote Pressure transmitter / Differential Pressure Transmitter

600 ℃ ultra-high temperature remote transmission pressure transmitter / remote transmission differential pressure transmitter cleverly uses the combination of ultra-high temperature silicone oil and internal isolation diaphragm. This makes the field application temperature greatly increased to about 600 ℃. Greatly expanded the application range of ultra-high temperature pressure / differential pressure measurement. It can be widely used in coal chemical industry and CSP industry.

https://www.drurylandetheatre.com/si-pt-series-melt-pressure-sensors-transducers-high-temperature/

How to Select a Pressure Transducer For High Temperature Environments

Define your high temperature pressure transmitter requirements using this checklist:

Process temperature?
Cooling mechanism?
Ambient temperature?
Pressure range?
Output signal? 4-20mA
Electrical connection?
Process connection?
Process media type?


Sino-Instrument supplies High-temperature pressure transmitters with a 4-20mA output.
Tolerant to high-temperature applications such as steam, food processing & engine monitoring.


High-temperature pressure transmitters are used in applications,
where the media temperature exceeds the temperature limits of standard pressure transmitters,
or where it is not possible to fit a standoff pipe,
pigtail or other cooling devices to reduce media temperature.

If you have a special request, you can just contact us for Technical Support.

Request a Quote

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SMT3151 TGP-Gauge Pressure Transmitter/Transducer

Gauge Pressure Transmitter/Transducer for process, oil and gas industry. With HART®-Communication and SIL2 (optionally).

Gauge Pressure Transmitter / transducer (GP) is a pressure transmitter for Gauge pressure measurement. Gauge pressure transmitter can measure the pressure of liquid, gas or steam. And convert it into 4 ~ 20mA DC signal output. The GP pressure transmitter can communicate with the HART Communicator, through which it can be set and monitored. Gauge pressure refers to pipeline pressure. “Gauge pressure” starts from atmospheric. Gauge Pressure plus atmospheric is the absolute pressure.

Sino-Inst offers a variety of Gauge pressure transmitters for industrial pressure measurement. If you have any questions, please contact our sales engineers.

Features of Gauge Pressure Transmitter

  • Nominal pressure: from 0 … 400 mbar up to 0 … 600 bar
  • Output signals : 2-wire: 4 … 20 mA ; others on request
  • Special Characteristics:
    • turn-down 1:10
    • two chamber aluminum die-cast case or stainless field housing
    • internal or flush welded diaphragm
    • HART®-communication
    • IS-version: Ex ia = intrinsically safe for gases and dusts
    • accuracy: 0,1 % FSO
  • Optional versions
    • IS-version: Ex d = flameproof enclosure
    • SIL2 – version according to IEC 61508 / IEC 61511
    • integrated display and operating module
    • special materials as Hastelloy® and Tantalum
    • cooling element for media temperatures up to 300 °C
  • Read more about: Common Units Of Pressure

Specifications of Gauge Pressure Transmitter

Use object:Liquid, gas or steam
Measuring range0-3.5~35kPa
0-10~100kPa
0-35~350kPa
0-0.1~1.0MPa
0-0.35~3.5MPa
0-1.0~10MPa
0-2.1~21MPa
0- 4.1~41Mpa
0- 6.0~60MPa
Output signal:4-20mAdc. Output, superimposed HART protocol digital signal (two-wire system)
Power source: External power supply 24V dc. Power supply range 12V ~ 45V
Installation in dangerous placesFlameproof ExdIIBT5Gb; (explosion-proof certificate no. :CE16.1163) Intrinsically safe ExiaIICT4/T5/T6Ga; (explosion-proof certificate no. : CE15.2354X)
Accuracy: ±0.1%, ±0.075%
Stability: ±0.2%/12 months of the maximum
range
Temperature effect:Including zero and range
for maximum temperature error of ±0.2% /
20 ℃
Power supply impact:Less than 0.005% / V of
the output range.
Vibration effect: In any axial direction, the
frequency is 200Hz, and the error is ±0.05% /
g of the maximum range.
Electronic circuit board work in: – 40 ~ 85 ℃;
Sensitive components work in :– 40 ~ 85 ℃;
Storage temperature :– 40 ~ 85 ℃;
With digital display: – 25 ~ 75 ℃ (run);
– 40 ~ 85 ℃ (no damage);
Relative humidity: 0 ~ 95%
Overpressure limit:2~5 times the maximum
range of pressure transmitter is not damaged.
Volume change:Less than 0.16cm3
Damping:The time constant is adjustable from
0.1 to 32.0s.
Startup time: 3s, no preheating required.
Flush membrane pressure connection interface

Extended reading: How to calibrate HART pressure transmitters

Common Industrial Applications of Gauge Pressure Transmitter

  • Mechanical and plant engineering
  • Chemical industry
  • Medical technology
  • Food and beverage
  • Oil and gas industry
  • Packaging and paper industry
  • Pharmaceutical industry

You may like: Explosion Proof Pressure Transmitter for Hazardous locations

What is a Gauge Pressure Transmitter?

Gauge Pressure Transmitter is one of the common industrial process pressure transmitters. Mainly used to measure the pressure of liquid, gas and other gauges. HS code: 9026201090.

A gauge pressure (GP) transmitter compares the process pressure with the local ambient air pressure. The gauge pressure transmitter has a port for real-time sampling of ambient air pressure.

High-precision gauge pressure transmitters may be affected by local environmental pressure fluctuations. Measurements above ambient pressure are expressed as positive numbers. A negative number indicates a measured value below ambient pressure.
The gauge pressure measurement value is indicated by the letter “g” after the unit of measurement (ie, inH 2 O (g) or psig).

Read more about: What is industrial pressure transmitter?

Gauge pressure transmitter working principle

SMT3151 TGP-Gauge Pressure Transmitter / Transducer is a diffusion silicon pressure transmitter. The working principle of the diffused silicon pressure sensor is based on the piezoresistive effect. Using the principle of piezoresistive effect, the pressure of the measured medium directly acts on the diaphragm of the sensor (stainless steel or ceramic). Make the diaphragm produce a slight displacement proportional to the pressure of the medium. To change the resistance value of the sensor. Use electronic circuits to detect this change. And convert and output a standard measurement signal corresponding to this pressure.

More about : Pressure transmitter Working Principle.

Difference between absolute, gauge and differential pressure

Comparison of absolute, gage and differential pressure

Absolute pressure

Absolute pressure is referred to as the vacuum of free space (zero pressure). In practice, absolute piezoresistive pressure sensors, measure the pressure relative to a high vacuum reference, sealed behind its sensing diaphragm. The vacuum has to be negligible compared to the pressure to be measured. Sino-Instrument’s absolute pressure sensors, offer ranges from 1 bar or even 700 mbar as well as barometric pressure ranges.

Gage pressure

Gage pressure is measured relative to the ambient atmospheric. The average atmospheric at sea level is 1013.25 mbar. Changes of the atmospheric, due to weather conditions, or altitude influences the output of a gauge pressure sensor.

A gauge pressure higher than ambient pressure is referred to as positive pressure. If the measured pressure is below atmospheric, it is called negative or vacuum gage pressure. In general, a vacuum is a volume of space that is essentially empty of matter.

According to its quality vacuum is divided into different ranges such as an e.g. low, high and ultra high vacuum.

Differential pressure

Differential pressure is the difference between any two process pressures p1 and p2. Differential pressure sensors must offer two separate pressure ports, with a tube or thread. Sino-Instrument’s amplified pressure sensors, are able to measure positive and negative pressure differences. i.e. p1>p2 and p1<p2.
These sensors are called bidirectional differential pressure sensors, with ranges of e.g. -1…+1.0 bar or -2.5…+2.5 mbar. In contrast, unidirectional differential pressure sensor only operate in the positive range (p1>p2). E.g. from 0…1.0 bar or 0…2.5 mbar. And the higher has to be applied to the pressure port defined as “high pressure”.

Gauge Pressure VS Absolute Pressure

  1. Gage pressure refers to pipeline pressure. It refers to the pressure measured with pressure gauges, vacuum gauges, U-shaped tubes and other instruments, also called relative pressure). “Gage pressure” starts from atmospheric pressure.
  2. The pressure directly acting on the surface of the container or object is called “absolute pressure”. The absolute pressure value starts with absolute vacuum.
    Absolute pressure actually refers to the gauge pressure plus the local atmospheric pressure (generally a standard atmospheric pressure can be 101.3Kpa).

Absolute pressure = gauge pressure + one atmosphere
If the unit is MPa, absolute pressure = gauge pressure + 0.1MPa

Read more about: Absolute Pressure Vs Gauge Pressure Measuring Instruments

More Featured Pressure Transmitters:

Q & A

What is the difference between pressure gauge and pressure transmitter?

The difference between pressure transmitter and pressure gauge are:
1. The accuracy of standard instruments required for pressure transmitter calibration is much higher than that required for pressure gauges.
2. The pressure gauge only needs to verify a pair of input and output relationships. The pressure transmitter may need to verify the relationship between the input and the communication data.
3. The calibration of the pressure gauge must have corresponding measurement qualifications. Pressure transmitters are generally not required except for production plants and new construction.
4. The pressure gauge has poor accuracy and no output. Do not use a hand-operated device. Generally check 5 points, the difference between the back and forth is different. The intelligent pressure transmitter generally only needs to check the zero point and full range.
5. The output of the pressure gauge is scale indication, and its own display ability. The pressure transmitter is a current output, which must be connected to an ammeter of the corresponding accuracy level for display.

What is the working principle of pressure transmitter?

Pressure transmitter manufacturers use different terms for pressure measurement products of different designs, such as pressure sensor, pressure transmitter, pressure converter, etc.

In Sino-Inst, “pressure transmitter” is often used to describe pressure sensors equipped with standard electrical and mechanical interfaces and standard signal outputs.

The working principle of the pressure transmitter is as follows:
The pressure of the medium to be measured is transmitted through the standard process connection, and then affects the internal pressure sensor element. Internal electronic components convert the original transmitter signal into filtered, amplified, temperature compensated and standardized signals, such as 4 … 20 mA signals. The output signal is sent to the next unit for signal processing through standardized connectors or cables.

What is a strain gauge pressure transducer?

Strain gauge pressure sensors work based on the principle of resistance strain effect. There are two types of resistance strain gauges: metal strain gauges (metal wires or metal foils) and semiconductor strain gauges. The measured pressure causes the strain gauge to strain. When the strain gauge produces compressive strain, its resistance decreases. When the strain gauge produces tensile strain, its resistance increases. The change of the resistance value of the strain gauge, and then obtain the corresponding millivolt level potential output through the bridge circuit, and display the measured pressure with a millivoltmeter or other recording instruments, thereby forming a strain gauge pressure gauge.

What is pressure transducer used for?

In general, the pressure transmitter is mainly used to measure the pressure and liquid level of the medium. The pressure transmitter is an indispensable key component in the fluid industry. The pressure transmitter is mainly used in the following fields:
1. Petroleum, petrochemical, chemical industry, matching with throttling devices, providing accurate flow measurement and control. It can measure the pressure and liquid level of pipelines and storage tanks.
2. Electric power, city gas, and other company businesses that require high-stability and high-precision measurement.
3. Pulp and paper making are used in places requiring chemical resistance and corrosion resistance.
4. Steel, non-ferrous metals, ceramics, used in furnace pressure measurement and other places that require high stability and high precision measurement, and used in places where stable measurement is required under strict control (temperature, humidity, etc.).
5. Machinery and shipbuilding are used to strictly control places requiring stable measurement under high precision conditions.

How does a 3 wire pressure transducer work?

The three wires of a 3-wire pressure sensor are generally red, black, and yellow, which are power supply positive, power supply negative, and signal lines. The power supply is positively connected to the positive pole of the DC power supply, the power supply is negatively connected to the negative pole of the DC power supply, and the signal line is connected to the signal input port of the device.

The so-called three-wire system is to use a wire for the positive end of the power supply, a wire for the positive end of the signal output, and a common wire for the negative end of the power supply and the negative end of the signal. The power supply is mostly 24v.dc, the output signal is 4-20ma.dc, the load resistance is 250ω or 0-10ma.dc, and the load resistance is 0-1.5kω; some also have ma and mv signals, but the load resistance or input The value of resistance varies with the output circuit.

The title of several-wire system comes after the birth of two-wire transmitter. This is the result of the widespread application of electronic amplifiers in meters. The essence of amplification is an energy conversion process, which is inseparable from power supply. Therefore, the first to appear is a four-wire transmitter; that is, two wires are responsible for the power supply, and the other two wires are responsible for outputting the amplified signal (such as voltage, current, etc.).

HH3151 HART Pressure Transmitter

HART pressure transmitter is the smart pressure transmitter in the process industry. With 4-20mA, HART. So, you can calibrate your pressure transmitters with HART communicators.

HART pressure transmitter configured through distributed control system (DCS) or HART communicator. The HART pressure transmitter is compatible with the Highway Addressable Remote Transmitter (HART) communication protocol. The HART function can transmit pressure transmitter data through an AC digital signal. The AC digital signal uses a 4-20mA analog output signal as a carrier. This eliminates the need for additional wires and connectors.

HH3151 HART Smart pressure transmitter that provides simplified field change, while communicating asset management data utilizing the latest HART 7 specification.

Sino-Inst offers a variety of HART pressure sensors for industrial pressure measurement. If you have any questions, please contact our sales engineers.

Features of HART pressure transmitter

HART pressure transmitter is a complete product line of liquid level, differential pressure, gauge pressure and absolute pressure transmitter. Models include flushing diaphragms and sanitary flanges for liquid level measurement, hydrostatic tank metering – HTG. And wetted parts of various materials to suit the process requirements.

3151 HART pressure transmitter
  • All models can be supplied with various remote seals.
  • Update output current in 100 ms with 0.75 µA/bit resolution;
  • Improved performance due to dedicated math co-processor;
  • Multi-drop operation mode;
  • PID control function;
  • Supports DTM and EDDL;
  • Bi-directional flow measurement;
  • With FMEDA analysis and MTBF of 244 year.

What is a HART transmitter?

HART transmitters are much more complicated.
The HART transmitter has the same pressure input and 4-20 mA output. But it also has an analog current loop output. The device contains some digital variables and settings. Access to these digital parameters requires the use of a HART configurator or communicator. This is essential for maintaining these devices.
Just like Hart Communicator 375.
In fact, many HART devices, cannot be maintained without access to digital parameters.

You may like: Verabar Flow Meter

What is HART calibrator?

HART calibrator is our HART communicator for calibrating instruments. For example pressure transmitter, DP transmitter, liquid level transmitter, flowmeter, and temperature transmitter.
HART communication protocol (Highway Addressable Remote Transducer) is a hybrid analog + digital industrial automation open protocol.
Its most significant advantage is that it can communicate through the traditional 4–20 mA analog instrument current loop, sharing only a pair of wires used by the analog host system.
We use this protocol in the HART calibrator.

HART communicator (such as HART 475) is the most common HART calibrator.
The proprietary calibration process ensures optimal temperature compensation. This limits the thermal impact on the sensor output.
It is suitable for the global process control industry. It provides a cost-effective solution for the use of conventional HART transmitters (such as the HART 475 field communicator).

HART protocol

What is HART pressure transmitter?

HART pressure transmitters

HART pressure transmitter for configuration via distributed control system (DCS) or HART communicator.

The HART pressure transmitter is compatible with the Highway Addressable Remote Transmitter (HART) communication protocol. This protocol is the most popular standard used by intelligent field devices and is used by the process control industry.
The HART function can transmit pressure transmitter data through AC digital signals. It uses 4-20mA analog output signals as a carrier. There is no need for additional wires and connectors.

HART pressure transmitter can also be used with a paperless recorder.

How to calibrate HART pressure transmitters

A pressure transmitter is one of the most common instruments in a process plant. To assure its accuracy, it needs to be calibrated.

But what do you need to calibrate it and how is it done?

You may know how to calibrate a pressure transmitter? Or, how to calibrate a differential pressure transmitter? Then, calibrate HART pressure transmitters, kind of like pressure transmitter calibration using a hart communicator. Pressure transmitter manufacturers have improved accuracy and technology, designed into these smart pressure measurement devices.

To calibrate a pressure transmitter, you need:

loop supply (if not connected to the controls system’s loop supply);
a pressure generator to generate input pressure;
an accurate calibrator to measure the input pressure;
an accurate calibrator to measure the output mA current.

Typically, the pressure transmitter is a HART protocol transmitter. So in case, there is any need to adjust/trim it, you will need to use a device supporting HART communication.

How to calibrate HART pressure transmitters?

Explaining how to do the calibration would result in quite a long text. So we have put together a video for you instead. The video shows you how to calibrate and trim a HART pressure transmitter. Please have a look at the video: How to calibrate HART pressure transmitters

Video source: https://www.youtube.com/watch?v=4wLCqH0M9fU&t=9s

HART Pressure Transmitters Calibration Steps

How to calibrate HART pressure transmitters?

Total Time:

1. Isolate the transmitter from the process being measured and its loop wiring.

2. If measuring the mA signal across the transmitter test diode leave the wires intact, but note this method does not give the best mA measurement accuracy.

3. Connect the mA measurement jacks of the 754 to the transmitter.

4. Connect the pressure module cable to the 475, and connect the transmitter test hose from the hand pump to the transmitter.
Press the HART button on the calibrator to see the configuration of the transmitter.

5. Press HART again and the calibrator will offer the correct measure/source combination for the test.

6. If documenting the calibration press As-Found, input the test tolerance and follow the prompts.

7. If the measured mA signal at the test points is found within tolerance the test is complete.
If not, change is required.
Select, adjust, and trim the pressure zero, mA output signal and input sensor.

If you still do not know, how to check the pressure transmitter?  Or, how to calibrate a pressure transmitter.

Just contact us.

HART pressure transmitter working principle

HART pressure transmitter is one type of smart pressure transmitter.

HART pressure transmitter connection

Principle and Application of Diffusion Silicon Pressure Transmitter

The pressure of the measured medium directly acts on the diaphragm of the sensor (stainless steel or ceramic). Causing the diaphragm to generate a micro-displacement proportional to the pressure of the medium. The resistance value of the sensor changes. The electronic circuit detects this change and converts and outputs a standard measurement signal corresponding to this pressure.

Principle of capacitive pressure transmitter

The capacitive pressure transmitter is mainly composed of a capacitance sensor and circuit board. The sensor implements pressure-capacitance conversion. The circuit board converts the capacitance to a two-wire 4-20mA. When the process pressure is applied to the isolation diaphragm from both sides (or one side) of the measuring chamber, it is transferred to the central diaphragm of the chamber through the silicone oil filling liquid. The central diaphragm is a diaphragm with tensioned edges. Under the action of pressure, a corresponding displacement is generated. This displacement creates a change in differential capacitance! And through the adjustment, oscillation, and amplification of the electronic circuit board! Converted into 4-20mA signal output! The output current is directly proportional to the process pressure!

pressure transducer often called a pressure transmitter, is a transducer that converts pressure into an analog electrical signal.

Although there are various types of pressure transducers, one of the most common is the strain-gage base transducer.

The conversion of pressure into an electrical signal is achieved by the physical deformation of strain gauges, which are bonded into the diaphragm of the pressure transducer, and wired into a Wheatstone bridge configuration.

Pressure applied to the pressure transducer produces a deflection of the diaphragm, which introduces strain to the gages.

The strain will produce an electrical resistance change proportional to the pressure.

In general, a pressure transmitter consists of three main components: a pressure sensor, a measuring circuit, and a process connection.

The main function of the pressure transmitter is to convert the physical parameters of the gas, liquid and other physical parameters of the pressure sensor into a standard electrical signal.

The standard electrical signal is more convenient for indicating the alarm device, the adjusting device, the recorder, and the secondary instrument.

Read more about Pressure Transmitter Working Principle

HART Smart Explosion Proof Pressure Transmitter

HART Explosion-proof pressure transmitters are available in a wide range of specifications. Easy to install and use, safe and explosion-proof.

They can be used in petrochemical, electric power, metallurgy, pharmaceutical, food processing, and other industries. Products follow the “IEC” standard. And explosion-proof pressure transmitters are renowned.

The company’s high-precision, high-stability pressure sensor assembly, through high-reliability amplifier circuit. And precision temperature compensation. The absolute or gauge pressure of the measured medium is converted into: 4 ~ 20mA, 0 ~ 5VDC, 0 ~ 10VDC and 1 ~ 5VDC,
and other standard electrical signals.

High-quality sensors hermetically sealed soldering technology and a complete assembly process, ensure excellent quality and performance.

Explosion-proof pressure transmitters are used in the following industries:

  • Compact explosion-proof pressure transmitter
  • Compact explosion-proof pressure transmitter
  • Industrial site process pressure detection
  • Laboratory pressure calibration system
  • Navigation and shipbuilding Aviation and aircraft manufacturing
  • Air separation equipment and thermal power unit
  • Energy management system
  • Hydraulic and pneumatic measurement and control system

You may like: Turbine flow meters | Magnetostrictive level sensor| Coriolis mass flow meter

What are differential pressure transmitters?

Differential pressure (DP) transmitter, also called differential pressure transducer. Differential pressure transmitters measure the difference between two pressures. Sino-Instrument supplies Differential Pressure Transmitters For differential pressure measurement.

Differential Pressure Transmitters
For differential pressure measurement
pressure ranges 0 … 1 mbar up to 0 … 70 bar

Extended reading: Smart Differential Pressure Transmitter

Sino-Instrument offers over 10 hart Transducers. About 50% of these are 4-20ma Low-Pressure Transducers, 40% are Differential Pressure Gauge, and 20% are Diaphragm Seal Pressure transmitters, 20% are 4-20ma differential pressure transmitters.

Sino-Instrument sells through a mature distribution network that reaches all 50 states and 30 countries worldwide. HART Pressure Transmitter products are most popular in Domestic Market, Southeast Asia, and Mid East.  You can ensure product safety by selecting from certified suppliers, with ISO9001, ISO14001 certification.

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More featured products

Diaphragm Seal Pressure Transmitter

Diaphragm seal pressure transmitter, with flange connection, direct mount. Diaphragm seal systems protect pressure transmitters from hot, viscous, contaminated, or corrosive media.

Diaphragm seal pressure transmitter with flange direct mount. Diaphragm seals, also known as chemical seals or flush seals. Diaphragm seals work with pressure transmitters, pressure gauges. To prevent the process medium from entering into the pressure-sensing assembly. So, Diaphragm seal systems protect pressure transmitters from hot, viscous, contaminated, or corrosive media. Diaphragm seal connection can work with the capillary, flange, and manifold. Like remote seal pressure transmitter, DP level transmitter.

Sino-Inst offers a variety of Diaphragm Seal Pressure Transmitters for industrial pressure measurement. If you have any questions, please contact our sales engineers.

Features of Diaphragm seal pressure transmitter

  1. Diffusion silicon isolation sensor
  2. Flange installation
  3. Large size diaphragm, fully welded and sealed, long-term reliable and durable
  4. Aluminum alloy junction box with strong seal and good outdoor installation
  5. Used for pressure measurement of gas, liquid and steam
  6. Anti-corrosion metal diaphragm optional
  7. With LCD display optional
  8. Especially suitable for high temperature or viscous liquid
  9. The flange size is customized according to customer requirements. And the installation is flexible and diverse

Read more about Steam pressure transmitter-Pressure measure on steam pipeline 

Specifications of Diaphragm Seal Pressure Transmitter

ModelTransmitter type
SI-1305Flange level transmitter
CodeScale range
2 3 4 50-20~100kPa(0-2000~10000mmH2O)
0-70~350kPa(0-7~35mH2O)
0-200~1000kPa(0-20~100mH2O)
0-700~3500kPa(0-70~350mH2O)
CodeOutput form
ELinear output 4-20mAdc
SFLinear output 4-20mAdc+HART signal,Full function buttons on site
FMODBUS-485 signal
CodeFlange standard (high pressure side flange)
AANSI American Standard (HG20615)
DDIN European standard(HG20592)
CodeProcess connection size
ANSI American Standard (HG20615)DIN European standard(HG20592)
251″DN25
401.5″DN40
502″DN50
803″DN80
004″DN100
CodeProcess connection withstand voltage rating
ANSI American Standard (HG20615)DIN European standard(HG20592)
A150LBPN16/25
B300LBPN40
C600LBPN64
D900LBPN100
CodeMeasuring diaphragm
A316 Stainless steel
BHastelloy C
CMonel
DTantalum
ETitanium
FSpecial requirements
CodeInsert barrel lengthInsert barrel material
A0 mmNone
B50 mm316L Stainless steel
C150 mm316L Stainless steel
D200 mm316L Stainless steel
CodeFilling liquid
DOrdinary silicone oil  (-40~104℃)
FHigh temperature silicone oil   (-40~304℃)
SInert liquid  (-40~204℃)
CodeShell materialConduit inlet dimensions
ALow copper aluminum alloy polyurethane coatingM20×1.5
BLow copper aluminum alloy polyurethane coating1/2-14 NPT
CStainless steelM20×1.5
DStainless steel1/2-14 NPT
CodeOptional parts
M10~100%  Linear indicator
M4LCD Multi-function digital display
DaFlameproof  ExdIIBT5Gb;(explosion-proof certificate No. : CE16.1163)
FaIntrinsically safe ExiaIICT4 / T5 / T6Ga;(explosion-proof certificate No. : CE15.2354X)
CXWith corresponding 316 flushing ring

You may like: Explosion Proof Pressure Transmitter for Hazardous locations

Applications for Diaphragm Seal Pressure/ Differential Pressure Transmitters

The application which is suitable for diaphragm seal system… For measuring the liquid level, density, flow, and pressure of :

  • high/low temperature fluids
  • highly corrosive/high viscosity fluids
  • the fluids which may cause clogging of impulse piping in the low temperature
  • toxic fluids
  • the fluids containing suspended solids which are deposited in the impulse piping and may cause clogging.\

Extended reading: Featured Diaphragm Seal Pressure Transmitters

What are the application considerations for diaphragm seals?

The biggest advantage of the diaphragm pressure transmitter is that different diaphragm materials can be selected. According to different corrosion, media to achieve the best corrosion resistance. The commonly used diaphragm materials are SUS316L stainless steel. Tantalum, Hastelloy, Monel, Pure titanium, F4, etc. 

When choosing a diaphragm pressure transmitter, in addition to the correct choice of structure and range, the more important thing is to choose the material. The so-called reasonable is to consider its corrosion resistance, but also to consider the economy. For example, the corrosion resistance of the tantalum diaphragm and Hastelloy is excellent, but it is expensive. Only used in environments with high corrosivity and other cheap materials are not suitable.

The following table introduces several common corrosion-resistant materials that can be selected for corrosion media. For your reference.

Corrosive mediumTin bronze (QSn6.5-0.4)SUS316Pure tantalum (Ta)Monel (Ni70Cu30)Hastelloy (HC)Polytetrafluoroethylene (F4)
Sulfuric acid (H2SO4)VVVV
Nitric acid (HNO3)VVV
Hydrochloric acid (HCI)VV
Phosphoric acid (H3PO4)VVVVV
Acetic acid (CH3COOH)VVVV
Caustic soda (NaOH)V
Soda ash (Na2CO3)VV
Baking soda (NaHCO3)VV
Chlorine (CI)Dry: VDry: VDry: VVV
Wet: ╳Wet: ╳Wet: ╳
Bromine (Br2)Dry: △Dry: ╳Dry: ○V
Wet: ╳Wet: △Wet: ╳
Ammonia (NH3)VV
Seawater (30% NaCI)VVV
Explanation of symbols: ○ ——best; △ ——conditional use; V——can be used;

Extended reading: Common Pressure Sensor Applications

What is diaphragm seal pressure transmitter?

The diaphragm seal pressure transmitter is the flange type pressure transmitter. This type of pressure transmitter, assembling diaphragm seals to field transmitters for the purpose of measuring pressure, differential pressure, level, and flow.

What is a diaphragm seal?

Diaphragm Seals, also known as Chemical Seals or Gauge Isolators, are used to isolate pressure instrumentation, like pressure gauges, pressure transmitters, pressure switches, level transmitters, and more from process media that is hot, corrosive, clogging, or otherwise damaging to the pressure instrument.

A diaphragm seal has two primary tasks:

  1. Separation of the measuring instrument from the process medium
  2. Transfer of the pressure to the measuring instrument

You may like: Diaphragm pressure gauge

What is remote seal?

The remote seal is used to prevent the medium in the pipeline from directly entering the pressure sensor assembly in the pressure transmitter. It is connected to the transmitter by a capillary filled with fluid. As a result, they’re often used in refining, petrochemical, and chemical plants.

Extended reading: SI-703 Flush Diaphragm Pressure Sensor

What are the advantages of diaphragm seals?

Diaphragm seals offer the advantage that the “contact surface” between pressure medium and diaphragm is relatively large. Thus ensuring accurate pressure measurement, especially for very low pressures (< 600m bar). Furthermore, they can be easily dismounted, e.g. for cleaning or calibration purposes.

How do diaphragm seals work?

Basically, diaphragm seals are used in all pressure measurement processes to avoid direct contact between the measuring instrument and the medium during this process. In addition, if the measuring point cannot be installed or read because the measuring point is located in a hard-to-reach location, a diaphragm seal can also be used. In both cases, the applied pressure is transferred to the measuring instrument through the system fill fluid in the diaphragm seal housing.
The diaphragm of the seal can be made of different materials, such as stainless steel, Hastelloy, Monel, or tantalum. In addition, coatings with ECTFE, PFA, or gold can also be used.

We can provide the best diaphragm seal design, materials, system fill fluid, and accessories for each application. The combined configuration of the pressure measuring instrument and the diaphragm seal is mainly determined by the special application conditions of the diaphragm sealing system.

How does a diaphragm pressure sensor work?

When the diaphragm seal pressure transmitter is working, the high and low-pressure side isolation diaphragms and the filling liquid transfer the process pressure to the center filling liquid. The filling fluid in the center transmits the pressure to the sensing diaphragm in the center of the δ-chamber sensor. The sensing diaphragm is a tensioned elastic element and its displacement changes with the differential pressure. For GP gauge pressure transmitters, the atmospheric pressure is applied to the low-pressure side of the sensing diaphragm. AP absolute pressure transmitter, the low-pressure side always maintains a reference pressure. The maximum displacement of the sensing diaphragm is 0.004 inches (0.10 mm). The displacement is proportional to the pressure. The two capacitance fixed plates of the measuring diaphragm are linearly converted into a 2-wire current, voltage, or digital HART output signal of 4-20mADC by the amplifying circuit.

Extended reading: How to calibrate HART pressure transmitters

Rosemount 1199 Diaphragm Seal System

Rosemount 1199 remote transmission diaphragm system provides the world’s most extensive product variety and specifications to meet the requirements of various measurements and applications.

There are the following types of remote transmission differential pressure/level transmitters:
1) PFW flat type remote transmission device
2) RTW thread installation type remote transmission device
3) EFW inserted barrel remote transmission device
4) RFW flange mounted remote transmission device
5) SCW hygienic remote transmission device

The 1199 remote diaphragm can be assembled to Sino-Inst differential, gauge, and absolute pressure transmitters and liquid level transmitters.

We can learn more about the 1199 remote diaphragms.

Techincal Support

Steam Pressure Transmitter

Steam pressure transmitters are widely used in the measurement and control of various high-temperature steam piping…

Cryogenic Pressure Transducers

Cryogenic pressure transducer for low temperature pressure measurement.  -196℃~+125℃、-260℃/-350c(especial). Sino-Inst offers a variety of Pressure Sensors…

FAQ

The purpose of the diaphragm seal is to protect expensive instruments. Its job is to transfer the pressure of the process medium through the membrane seal to the filling fluid and then transmit the resulting pressure wave to a pressure gauge or sensor at the head of the measuring assembly.
Choose a suitable diaphragm seal filling liquid.
The characteristics of the diaphragm seal fill fluid determine the performance of the sealing system to a large extent. Both in response time and temperature dissipation conditions.
The initial consideration in choosing a sealed diaphragm to fill fluid is the media compatibility of the process. The temperature and pressure of the process medium are also important factors because all the filling fluid expands or contracts with changes in temperature.
Remember that there is a direct relationship between the measured response time of the viscosity and the density of the filling fluid. More viscous filling fluids lead to longer response times.
In addition, the filling fluid with a higher density can have an impact on the mounting.
Types of filling fluid: glycerin, silicone oil, and halogenated carbon are the most commonly used sealing diaphragm filling fluids.

Extended reading: Flat Pressure Sensor for High Viscosity Fluids

Diaphragm seals are mounted to existing connecting flanges or welding sockets, which are welded to a pipeline, a process reactor, or a tank.

Extended reading: extrusion melt pressure transducer

A diaphragm seal can be mounted via a direct connection, a cooling element or a capillary.

Besides pressure sensors, we also supply torque sensors. What Is a Torque Transducer? How to Choose?

The combinations of diaphragm seals with flange connections can be used for processes with extreme temperatures and with aggressive, adhesive, corrosive, highly viscous, environmentally hazardous or toxic media. With its connection dimensions, the flange-type diaphragm seal is suitable for all currently used standard flanges and is mounted in lieu of a blind flange.

Extended Reading: Resistive Pressure Transducer

Diaphragm-sealed pressure transmitters are used when the medium is corrosive or will corrode the internal parts of the transmitter (for example, ammonia will corrode the copper in the transmitter).

Extended reading: High accuracy pressure transducers

The measurement accuracy of flat film and convex film is the same, but there is a difference in the measurement structure.
The choice of the two types of diaphragms is mainly based on the different applications.
For example, in regular occasions, the material is easy to flow and not easy to crystallize and block. Just use a flat diaphragm.
If the measuring medium is easy to crystallize and block, consider the convex diaphragm structure. Of course, we must also consider the installation and pressure pipe issues.

Sino-Instrument is a pressure transmitters manufacturer in China.

We offer all types of Diaphragm Seal Pressure Transmitters. Like Direct Mounted, flange-mounted, single flange, double flange, Remote Diaphragm SealsHigh Static, Digital Remote.

Most of our Diaphragm Seal Pressure Transmitters are used in oil, liquids, DP transmitterflow measurementlevel measurement (like the ultrasonic level measurement), density, and other process variables.

Diaphragm Seal Pressure Transmitters are generally available with three types of electrical output; millivolt, amplified voltage, and 4-20mA.

You can ensure product safety by selecting from certified suppliers, with ISO9001, ISO14001 certification. We will share more about instrument calibration, like the flow transmitter calibration.

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