Category Archives: Pressure

Pressure Transducers and Transmitters Manfacturer, China

A pressure transducer also called a pressure transmitter,

is a transducer that converts pressure into an analog electrical signal.

Pressure transmitters are used to measure the pressure,

or level of industrial liquids and gases.

The output is transmitted to a control system.

Accurate and stable process measurements ensure the safe,

reliable, and profitable operation of your plant.

Sino-Instrument is pressure transmitters manufacturer in China.

We offer all types of pressure transmitters.

Like Direct Mounted, flange-mounted, single flange,

double flange, Remote Diaphragm Seals, High Static, Digital Remote.

Most of our pressure transmitters are used in oil, liquids,

DP transmitter, flow measurement, level measurement, density,

and other process variables.

Pressure transducers are generally available with three types of electrical output;

millivolt, amplified voltage, and 4-20mA.

4-20 mA Output Pressure Transducers

These types of transducers are also known as pressure transmitters,

work with HART communicators.

Since a 4-20mA signal is least affected by electrical noise,

and resistance in the signal wires,

these transducers are best used when the signal must be transmitted long distances.

It is not uncommon to use these transducers in applications where the lead wire must be 1000 feet or more.

Choose the right pressure transducer for your application:

SI-2088 High Temperature Pressure Transducer

Posted on May 24, 2019 by KimGuo11

High Temperature Pressure Transducer is specially used for high temperature medium pressure measurement. Such as high temperature liquid, gas, steam, etc. The highest temperature is customized to 850℃.

High temperature resistant pressure sensor is selected as the signal measurement element. The transmitter structure includes a heat dissipation structure, and the high-precision signal processing circuit is located in the stainless steel housing. The sensor output signal is converted into a standard output signal, such as 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.

More Pressure Transmitters

Features of SI-2088 High Temperature Pressure Transducer

Working temperature –55 …850 ° C, customizable;
Pressure range can also be customized, such as 150MPa high pressure;
The sensor and pressure interface are fully welded structures, and the housing protection level is IP65;
The material in contact with the medium is stainless steel, which has good corrosion resistance;
It is suitable for pressure measurement of high temperature, low temperature and normal temperature media, and can work stably for a long time;
It is impact-resistant, vibration-resistant and corrosion-resistant;

High temperature pressure transducer 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.

Specifications of High Temperature Transducer

Range:	0 ～ 1KPa ～ 10KPa ～ 400KPa, -0.1 ～ 0 ～ 1 ～ 60 (MPa), 0 ～ 10KPa ~ 100MPa, Other pressure ranges can be customized.
Comprehensive accuracy:	0.25% FS, 0.5% FS
Output signal:	4-20mA (2/4-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 transmitters

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

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.

How to Select a Pressure Transducer For High Temperature Medium

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?

Featured Silicon Pressure Sensor

Posted on May 24, 2019 by KimGuo11

A Silicon Pressure Sensor is a pressure transmitter widely used in industry. It uses diffused silicon or ceramic piezoresistive sensors as pressure detection elements. It has strong overload capacity, good stability, and strong anti-interference ability. It has extremely high accuracy and repeatability, and the measurement interface has good corrosion resistance.

RFQ

Silicon Pressure Sensor Benefits

Silicon Pressure Sensor has a large signal output. It provides great advantages for the back-end transmission and conditioning circuit. It has high resolution and high sensitivity.
It can be compensated twice. The sensitivity temperature coefficient and zero temperature coefficient of Silicon Pressure Sensor can be compensated. Even the finished core can be compensated twice.
Silicon Pressure Sensors are relatively cheap and cost-effective.
The Silicon Pressure Sensor is small and easy to install. It can be installed and used in narrow locations.
316L stainless steel mechatronic structure with good durability.
Integrated dedicated chip, few discrete components, good temperature characteristics.

Industrial Silicon Pressure Sensor Technical Parameters

Pressure Media	Fluids, Gas
Supply Voltage	-30℃~160-350℃， customized up to -300~850℃
Operating Range	(Gage/Absolute Pressure)–Max(0～60)MPa, Min(0～0.5)KPa
Operating Range	(Negative Pressure)—Max(-100KPa～), Min(-0.2～0.2 )KPa
Accuracy	±0.5%(25℃)
Over Pressure	200% full scale
Long Term Stability	<0.25%FS per year
Response	<100ｍs
Output Signal	(4～20)mA+HART protocol（Current two-wire/three-wire, HART protocol）, etc.
Temperature Range	-30℃~160-350℃, Customized up to -300~850℃
Temperature Effects	0.00015%FS/℃
Pressure Connection	G1/2 female or user specified
Electrical Connection	Waterproof Connector(M20*1.5)
Protection Class	IP65

Silicon Pressure Sensor Applications

Silicon Pressure Sensor Mainly used to measure the pressure of gas, liquid and other objects. The parameters are then converted into standard telecom signals.

The application scope of diffusion silicon pressure transmitter mainly has the following:

Petroleum/Petrochemical/Chemical
Matched with the throttling device, it provides accurate flow measurement and control.
Measures pressure and level in pipes and tanks.
Electricity/city gas/other company business
Places such as measurement require high stability and high precision.
Pulp and paper
It is used in places requiring chemical resistance, corrosion resistance, etc.
Steel/non-ferrous metals/ceramics
It is used for furnace pressure measurement and other places requiring high stability and high precision measurement.
For use where stable measurements are required under strictly controlled (temperature, humidity, etc.) conditions.
Machinery/Shipbuilding
It is used in places where stable measurement is required under high-precision conditions such as strict control of temperature and humidity.

Extended reading: Featured Diaphragm Seal Pressure Transmitters

There are many types of pressure sensors. Such as resistance strain gauge pressure sensor. Semiconductor strain gauge pressure sensor. Piezoresistive pressure sensor. Inductive pressure sensor. Capacitive pressure sensor. Resonant pressure sensor, etc.

At present, the widely used pressure sensors include: diffused silicon piezoresistive pressure sensors, ceramic piezoresistive pressure sensors, sputtering film pressure sensors, capacitive pressure sensors, and sapphire pressure sensors with high temperature resistance.

But the most widely used is the piezoresistive pressure sensor, which has extremely low price, high precision and good linearity.

Extended reading: What is an air pressure transducer?

When the semiconductor silicon material is subjected to force, the atomic lattice changes.
That is, the spacing of the lattice changes. Then the carrier mobility of the silicon material changes.
changes, and the concentration changes. The lateral distribution structure and longitudinal distribution of carriers are disturbed.
The distribution structure of the material eventually leads to a change in the resistivity of the material. The above is half of the
A detailed elaboration of the piezoresistive effect of conductor silicon materials.

A pressure sensor that is also widely used, that is, a resistance strain sensor. Compared with a piezoresistive pressure sensor, the working process or working principle between the two is essentially different.

Piezoresistive Effect of Semiconductor Silicon Piezoresistive Pressure Sensor and Strain Effect of Metal Strain Gauge
The difference between the two should be: the output power of the former, that is, the change of the resistance value mainly depends on the material.
The change of the resistivity of the material. The output power of the latter, that is, the change of the resistance value depends on
Changes in material geometry (strain.

The sensitivity of semiconductor silicon material is high, and its sensitivity is 50 to 100 times that of metal strain gauges.

In 1954, Smith devoted himself to researching the piezoresistive effect of semiconductor silicon material. At the same time, he used it to make pressure sensors.

The silicon pressure sensor researched in the early stage is similar to the semiconductor strain gauge. After development and research, the N-type silicon wafer is doped with P-type impurities by diffusion or ion implantation. The resistance bar is customized. It is matched behind the resistance bar Connect a suitable bridge circuit to make an integrated chip.

It is the same as the use of resistance strain gauges. The chip cannot be used independently to complete the measurement work. It also needs to be firmly attached to the elastic element to sense the change in the measured pressure.

Diffused silicon piezoresistive pressure sensor refers to a sensor made by using the above-mentioned chip as a sensitive element.

The piezoresistive chip of the piezoresistive pressure sensor is packaged in a shell, and the periphery is fixed to form a silicon cup structure.

On the circular silicon diaphragm, four resistance strips with equal resistance value are made by the above-mentioned diffusion or ion implantation doping method.

Put two of them in the range of compressive stress. The other two are fixed in the range of tensile stress. Together they form a Wheatstone bridge measurement circuit.

Resistor strips are drawn from the bridge power supply terminal and output terminal.

The above-mentioned structure is packaged by the manufacturing method of an integrated circuit to obtain a diffused silicon piezoresistive pressure sensor.

Capacitive pressure sensor is a pressure sensor that uses capacitive sensitive elements to convert the measured pressure into an electrical output that has a certain relationship with it. The characteristics are that the input energy is low, the dynamic response is high, the natural effect is small, and the environmental adaptability is good.

It generally uses a circular metal film z or a metal-plated film as an electrode of the capacitor. When the film is deformed by pressure, the capacitance formed between the film and the fixed electrode changes. The output can be in a certain relationship with the voltage by measuring the circuit. electrical signal.

Capacitive pressure sensors belong to the polar distance variable capacitive sensors. They can be divided into single capacitive pressure sensors and differential capacitive pressure sensors

Current MEMS pressure sensors include silicon piezoresistive pressure sensors and silicon capacitive pressure sensors. Both are microelectromechanical sensors produced on silicon wafers.

The silicon piezoresistive pressure sensor uses high-precision semiconductor resistance strain gauges to form a Wheatstone bridge as a force-electricity conversion measurement circuit. It has high measurement accuracy, low power consumption and extremely low cost. Piezoresistive sensor for a Wheatstone bridge. If there is no pressure change, its output is zero and almost no power consumption.

Capacitive pressure sensors use MEMS technology to create a grid-like shape on a silicon wafer. The upper and lower two transverse barriers become a group of capacitive pressure sensors. The upper transverse grille is displaced downward by pressure. Changed the spacing between the upper and lower transverse grids. It also changes the size of the capacitance between the plates, that is, △ pressure = △ capacitance.

Extended reading: Industrial Pressure Transmitters|Buy from the manufacturer

SMT3151 TGP Gauge Pressure Transmitter/Transducer

Posted on May 23, 2019 by KimGuo11

What is a gauge pressure transmitter?

Gauge Pressure Transmitter/Transducer is a commonly used pressure measurement process instrument in industry. The gauge pressure transmitter measures the pressure signal at the reference end of atmospheric pressure.

An industrial gauge pressure transmitter is commonly used to monitor the process pressure of liquid, gas, steam, etc.

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

More Pressure Transmitters

Benefits of Gauge Pressure Transmitter

High accuracy: The pressure transmitter can perform high-accuracy measurements within the measurement range of 0~60MPa.
Excellent overpressure performance: Can withstand 2 times the pressure range.
Intelligent static pressure compensation and temperature compensation protect the transmitter from the influence of temperature, static pressure and overpressure, reducing errors.
LCD digital display with backlight
Built-in three-button quick operation and local adjustment function
Various anti-corrosion materials are available
Multi-faceted self-diagnosis function
Optional signals 0-10V, 4-20mA, RS485, HART protocol, etc.

Read more about: Common Units Of Pressure

Specifications of Gauge Pressure Transmitter

Use object:	Liquid, gas or steam
Measuring range	0-3.5～35kPa 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 places	Flameproof 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 the 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

Gauge pressure transmitter is the most commonly used detection instrument in industrial process control, which is widely used in various automatic control systems. Such as aerospace, military industry, petrochemical, chemical industry, oil well, electricity, shipbuilding, building materials, pipelines and many other industries.

It is generally used to measure pressure or absolute pressure in environments where the medium temperature is not too high, the corrosiveness is not strong, the viscosity is not high, and it is not easy to crystallize.

If low temperature, high temperature, corrosive medium measurement is required. Please contact our engineers for customization!

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

Explosion Proof Pressure Transmitter for Hazardous locations

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, gauge 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.

Gauge pressure

Gauge 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 gauge 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

Gauge 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). “Gauge pressure” starts from atmospheric 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.
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

Transmitters can convert physical signals into electrical signals.
For example, our pressure transmitter can convert pressure signals into 4-20mA. Liquid level transmitter can convert liquid level signals into 4-20mA.

Gauges are generally mechanical. There is no output of electrical signals. For example, pressure gauges and liquid level gauges. The measurement results can be measured and read intuitively.

When selecting a pressure transmitter, the concept of pressure type is involved: absolute pressure, gauge pressure, negative pressure and differential pressure.

Absolute pressure transmitter measures the absolute pressure of the medium in the equipment. Its reference pressure is an absolute value of 0. It has nothing to do with atmospheric pressure. Therefore, there will be a vacuum sealed cavity on the low-pressure side of the pressure core.

Gauge pressure transmitter measures the pressure based on atmospheric pressure. One side of the pressure transmitter is connected to the atmosphere, and the other side is connected to the measured pressure, so the reference pressure side is open to the atmosphere. It is generally used to measure the liquid level of pipelines and non-pressure tanks.

If you pay close attention to the outer shell of some gauge pressure transmitters, it is not difficult to find some small holes on it. These vents are reserved to keep the reference side connected to the atmosphere.

More Featured Pressure Transmitters and Pressure Measurement Solutions

**SI-512H High Temperature Pressure Sensor**

**SI-706 Combined Pressure and Temperature Sensor-Dual function**

We at Sino-Inst manufacture and supply various types of gauge pressure transmitters for various industries. Customized production is available based on your measurement requirements, including pressure range, temperature, accuracy, signal output, mounting thread, material, etc.

If you need to purchase a gauge pressure transmitter, or have any technical questions, please feel free to contact us.

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KimGuo11

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