SMT3151DP Smart Differential Pressure Transmitter

Smart Differential Pressure Transmitter measures an industrial differential pressure. Can Works with diaphragm seals, capillary, HART. Outputs standard signals (such as 4 ~ 20mA, 0 ~ 5V).

SMT3151DP smart differential pressure transmitter

A smart differential pressure transmitter is used to measure the liquid level, density, and pressure of liquid, gas, or steam. And then convert it into 4 ~ 20mA DC signal output. Smart can communicate with HART Communicator, and set and monitor through it. The DP transmitter is a transmitter that measures the pressure difference between the two ends of the transmitter. The differential pressure transmitter has two pressure interfaces. It is divided into a positive pressure end and a negative pressure end. In general, the pressure at the positive pressure end of the differential pressure transmitter should be greater than the pressure at the negative pressure end.

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

Features of SMT3151DP Smart Differential Pressure Transmitter

Blue and white custom housing smart differential pressure transmitter
  • Output signal 4-20mA output+HART communication;
  • Push Button Configuration;
  • Self-diagnosis capability;
  • Range coverage is 0-0.1KPa~41.0MPa;
  • Good stability, high precision, adjustable damping, strong resistance to one-way overload.
  • Explosion-proof housing structure.
  • LCD display

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SMT3151DP smart differential pressure is the pressure signal measured at the reference end of the low-pressure side. There are two ports connected to the processing pipeline.

Smart differential pressure transmitter is suitable for measuring pressure from -100mbar to 70bar. The maximum working pressure is up to 410bar. Sino-Inst’s SMT3151DP smart differential pressure transmitter is a rugged low-range / high-voltage line process differential pressure transmitter. Optional HART communication and 4-20 mA output provide an accurate measurement. Equipped with internal button adjustment for range and configuration and integrated LCD display.

Extended reading: How to calibrate HART pressure transmitters

Specifications of SMT3151DP Smart Differential Pressure Transmitter

Use object: liquid, gas or steam

Measuring a range of SMT3151DP smart differential pressure transmitter:

ModelTransmitter type
DPPressure transmitter
HPAbsolute pressure transmitter
CodeScale range
CodeOutput form
ELinear output 4-20mAdc
SFLinear/square root output 4-20mAdc +HART signal,,Full function buttons on site
FMODBUS-485 signal
Structural materialsFlange 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)

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Applications of Smart Differential Pressure Transmitter

SMT3151DP smart differential pressure transmitter is suitable for applications like:

Flow measurement;

Level monitoring;

Steam measurement;

Filter or pump differential pressure;

Critical process monitoring.

The common DP transmitter is the most commonly used test instrument in industrial process control.It is widely used in various automatic control systems.

Such as aerospace, military, petrochemical, chemical. Oil Wells, electric power, ships, building materials.Pipelines and many other industries.

Generally used in liquid, gas or steam differential pressure, flow measurement. The medium temperature is not too high, corrosion is not strong, viscosity is not high, not easy to crystallize and other environments.

If the working static pressure exceeds 13MPa, a high static differential pressure transmitter should be selected.

You may like: Differential Pressure Transmitter Installation Guide

The common DP transmitter is the most commonly used test instrument in industrial process control.It is widely used in various automatic control systems.

Such as aerospace, military, petrochemical, chemical. Oil Wells, electric power, ships, building materials.Pipelines and many other industries.

Generally used in liquid, gas or steam differential pressure, flow measurement. The medium temperature is not too high, corrosion is not strong, viscosity is not high, not easy to crystallize and other environments.

If the working static pressure exceeds 13MPa, a high static differential pressure transmitter should be selected.

You may like: Differential Pressure Transmitter Installation Guide

Differential pressure transmitter for liquid level measurement

Differential Pressure (DP) Level Measurement uses pressure readings and specific gravity to output level. DP Level is a common measurement technique that is used in a wide variety of applications. Solutions include standard transmitter connections and integrated transmitters with direct or remote mount seals that can be configured in tuned, balanced, and electronic systems. Additional Wireless options are also available.


Differential pressure transmitter for flow measurement

Differential Pressure Flow meters, also known as DP flow meters. Differential Pressure (DP) flow meters introduce a constriction in the pipe, that creates a pressure drop across the flow meter. The calculation of fluid flow rate, by reading the pressure loss across a pipe restriction, is the most used flow measurement technique in industrial applications. Differential pressure flow meters are suitable for water flow measurement, oil, steam or gas flow measurement.


Differential Pressure Transmitter Pdf

Smart pressure transmitter working principle

The working principle of the smart pressure transmitter (gauge pressure) / absolute pressure transmitter is:

The pressure passes through the isolated diaphragm and the pressure-conducting medium. It acts indirectly on the metal surface. The thickness of the metal film is different. As a result, the diaphragm is slightly deformed. The maximum shape variable does not exceed 0.1mm. A high-precision circuit that measures the deformation of the diaphragm converts this small deformation into a voltage signal proportional to the pressure. After linearization and temperature compensation processing, a dedicated chip is used to convert the voltage signal into an industry standard 4-20ma current signal or 1-5v voltage signal.

The metal capacitive pressure sensor used to measure the diaphragm detection circuit contains a linear circuit and a temperature compensation circuit. Therefore, the entire transmitter can achieve high accuracy and high stability. Metal capacitive pressure sensor has extremely high overload resistance. And has excellent performance in micro-pressure measurement.

Working principle of Smart differential pressure transmitter

SMT3151DP intelligent differential pressure transmitter uses advanced microprocessor technology and digital communication technology. The basic principle of differential pressure transmitter is: divide a space with sensitive elements (multi-purpose capsule) into two chambers. Introduce pressure into the two chambers separately. The sensor produces displacement (or displacement trend) under the combined action of the two pressures. This displacement is proportional to the pressure difference (differential pressure) between the two chambers. Convert this displacement into a standard signal output that can reflect the magnitude of the differential pressure.

You may like: differential pressure transmitter working principle|Working Principle of pressure level transmitters| differential pressure level transmitter working principle

Type selection of SMT3151DP smart differential pressure transmitter:

Before selecting the type, the User shall make clear:
The temperature. Corrosion. Measuring range. Use.
Whether the medium under test is explosion-proof.
Whether the oil shall be forbidden.
Whether the medium is easy to crystallize or thicken.
Whether the diaphragm flange connection is needed, etc.

Read more What is a diaphragm seal?

3 Methods for SMT3151DP Smart Differential Pressure Transmitter Application Measurement:

(1) The differential pressure transmitter is combined with the throttling device (like the orifice plate). To convert the flow rate according to the differential pressure value, generated before and after the throttling device.

SMT3151DP smart differential pressure transmitters supplier

(2) Measuring the height of the liquid by the pressure difference, generated by the gravity of the liquid itself.

(3) Directly measure the pressure difference between different pipes, and closed pressure vessels to convert the liquid level height.

The SMT3151DP smart series differential pressure transmitters are modular in design. And consist of a sensor module with an integrated electronic adapter unit. And an amplifier module with a local button unit.

The sensor module includes a differential pressure sensor and a temperature sensor for simultaneous measurement of differential pressure.

So the SMT3151DP smart series differential pressure transmitter has excellent static pressure characteristics and temperature characteristics.


Smart transmitters work on the function of microprocessors for signal transmission.

Smart pressure transmitter consists of two parts: smart sensor and smart electronic board.

The intelligent sensor part includes: capacitive sensor, measuring diaphragm detection circuit, temperature sensor and temperature compensation circuit.

The part of the intelligent electronic board includes: a microcomputer controller and peripheral circuits. It completes the conversion of the pressure signal to 4-20mA dc.

Extended Reading: Digital Pressure Sensor-RS485

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 pressure transmitter:

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

Extended reading: Silicon Pressure Sensor

Simply put, a differential pressure transmitter is a device that measures two opposing pressures in a pipe or vessel. Differential Pressure (DP) transmitters measure the difference between two pressures. They use a reference point called the low-side pressure and compare it to the high-side pressure. Ports in the instrument are marked high-side and low-side. The DP reading can be either negative or positive depending on whether the low-side or high-side is the larger value. A DP transmitter can be used as a gauge pressure transmitter if the low-side is left open to the atmosphere.

Extended reading: Featured Diaphragm Seal Pressure Transmitters

The most common and useful industrial pressure measuring instrument is the differential pressure transmitter. This equipment will sense the difference in pressure between two ports and produce an output signal with reference to a calibrated pressure range.

The differential pressure transmitter can be used in combination with other accessories and can be used to measure liquid level and flow.

Differential pressure transmitters and pressure transmitters have many similarities. It can be mixed and used most of the time. As long as it is within the range of the differential pressure transmitter, it can measure not only positive pressure but also negative pressure. When measuring positive pressure, the negative port is open to atmosphere, and when measuring negative pressure, the positive port is open to atmosphere.

Differential pressure transmitters can also measure flow, pipeline pressure difference, tank liquid level, bubble water level, dust, or medium that is easy to crystallize and viscous and fluidity is not good.

Sino-Instrument is a leading manufacturer in the field of measurement and control in China.
One big reason for the continued growth of Sino-Instrument is our willingness to listen to our customers’ specific needs.

And develop solutions to meet those needs for the Oil and Gas, Power Generation, and Nuclear industries. In fact, many of the products we deliver are specially engineered to order. Such as pressure gauges, bimetal thermometers, thermocouples, pressure calibrators, bench pressures, etc.

It is widely used in electric power, petroleum, chemical, machinery, metallurgy, cement, glass, cooking, and other industries in various countries.

More products continue to be developed that integrate features, such as wireless and HART technologies (AMS TREX DEVICE). All our products are engineered and manufactured, at Sino-Instrument world headquarters located in Xi’an, China.

Sino-Instrument manufactures a wide variety of mechanical and electronic devices. To measure pressure, level measurement, temperature, and flow. And we’re working constantly to improve our product platform.

Sino-Instrument specializes in supplying electromagnetic flowmeters.
vortex flowmeter. gas turbine flowmeter. vortex flowmeter. orifice flowmeter. liquid turbine flowmeter. natural gas flowmeter. steam flowmeter. thermal gas flowmeter. elliptical gear flowmeter. magnetic flap level gauge. ultrasonic level gauge. diaphragm pressure gauge.
digital pressure gauge. diaphragm pressure gauge. stainless steel Series of flowmeters.

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This entry was posted in Pressure, DP Transmitters, Smart Transmitters by KimGuo11. Bookmark the permalink.

About KimGuo11

Wu Peng, born in 1980, is a highly respected and accomplished male engineer with extensive experience in the field of automation. With over 20 years of industry experience, Wu has made significant contributions to both academia and engineering projects. Throughout his career, Wu Peng has participated in numerous national and international engineering projects. Some of his most notable projects include the development of an intelligent control system for oil refineries, the design of a cutting-edge distributed control system for petrochemical plants, and the optimization of control algorithms for natural gas pipelines.