SI-3151 Capacitive-Absolute Pressure Transmitter

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SI-3151 Capacitive-Absolute Pressure Transmitter

SI-3151 Absolute Pressure Transmitter is a capacitive pressure transmitter. It can be used not only for Absolute Pressure, but also for gauge pressure measurement.

SI-3151 Capacitive-Absolute Pressure Transmitter contains linearity and temperature compensation circuits inside. So the whole transmitter can achieve high precision and high stability.

Capacitive pressure sensor has extremely high anti-overload performance and excellent performance in micro-pressure measurement. Widely used in various complex industrial environments.

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Pressure Sensors

Advantages of SI-3151 Capacitive-Absolute Pressure Transmitter

The characteristics of capacitive pressure transmitters are:

  1. High output signal: The circuit of the pressure transmitter can directly convert a small change in capacitance into a high output signal. without signal amplification. The piezoresistive sensor (thin mode, C-type) has disadvantages such as low output signal and easy to be interfered by external signals. This is usually the main reason why the sensor has poor stability, is greatly affected by temperature, and is susceptible to electromagnetic wave interference.
  2. Good long-term stability: Compared with other similar products, the pressure transmitter has higher stability. Unlike other sensors such as metal strain sensors, capacitive pressure transmitters have little creep, aging and temperature effects. Almost all adverse factors have less impact on the output stability of capacitive sensors than other forms of sensors. The zero point stability of the pressure transmitter can reach 0.05%FS/year.
  3. Mechanical deformation: A small change in the distance between the plates of the sensitive capacitor mold can produce a measurable voltage signal change. The small mechanical deformation greatly reduces the hysteresis and non-repeatability errors of the sensor, and the speed of the sensor is also greatly improved.
  4. Wide measurement range: SI-3151 Capacitive-Absolute Pressure Transmitter has a very wide measurement range, it can accurately measure the pressure in the range of 25Pa ~ 70MPa, and has extremely high stability.
  5. High performance: The capacitive material used to make the transmitter has extremely stable physical and chemical properties. Make the product have extremely high performance. Sensors with accuracy up to ± 0.02%FS, stability better than ± 0.05%FS. Such high performance is difficult to achieve by products using other sensitive principles.

SI-3151 Capacitive-Absolute Pressure Transmitter Specifications

Measuring mediumLiquid, gas or Steam;
Measure Range0-6.0～60MPaa
Accuracy class:0.1, 0.25, 0.5
Overload capacity:Ranges 3 to 8 withstand 0 (absolute pressure) ~ 13.78MPa pressure transmitter without damage; range 9 pressure does not exceed 31.29MPa; range 0 pressure does not exceed 51.4MPa; normal working pressure is 3.43kPa (absolute pressure) to the upper limit of the range.
Long-term stability:Less than 0.25%FS/year, less than 0.5%FS/year
Power supply:15～36 VDC (standard voltage 24VDC)
output signal:(4～20)mA (two-wire system) HART communication
Display method:4-digit LCD display
Operation method:Comes with 2 light touch buttons
Zero Span MigrationDirectly transfer the zero point and range by pressing the button
Operating temperature:(-40～80)℃ Compensation temperature: (-20～70)℃
Process connection:M20×1.5 external thread or specified by the user
Isolation diaphragm material:316 stainless steel, Monel, Hastelloy, etc. User notes.
Shell material:Aluminium Alloy
Protection class:IP65

absolute pressure transmitter working principle

Pressure (gauge pressure)/absolute pressure transmitter is a pressure signal measured with atmospheric pressure/vacuum as the reference terminal, and only one port is connected to the process pipeline.

The working principle of metal capacitive pressure (gauge pressure)/absolute pressure transmitter is:
When the pressure acts indirectly on the surface of the metal measuring diaphragm (elastic measuring element) of different thickness through the isolation diaphragm and the pressure guide medium. Make the diaphragm slightly deformed. The maximum deformation does not exceed 0.1mm. A high-precision measurement circuit converts this tiny deformation into a voltage signal that is linear with the differential pressure signal. After linearization, temperature compensation. Then use a dedicated chip to convert this voltage signal into an industry standard 4-20mA current signal or 1-5V voltage signal.

The working principle of capacitive pressure transmitter and capacitive absolute pressure transmitter is the same as that of differential pressure transmitter, the difference is that the pressure of low pressure chamber is atmospheric pressure or vacuum.

absolute pressure transmitter working principle

Order Guide

Model Transmitter type
SI-3151GP Pressure transmitter
SI-3151AP Absolute pressure transmitter
Code Scale range
(0~X)KPa 0- 6.0～60MPa
Code Output form
E Linear output 4-20mAdc
SF Linear output 4-20mAdc+HART signal，Full function buttons on site
F MODBUS-485 signal
Code Structural materials
Flange connector Exhaust/Drain valve Isolation diaphragm Filling liquid
22 316 Stainless steel 316 Stainless steel 316 Stainless steel Silicone oil
23 316 Stainless steel 316 Stainless steel Hastelloy C Silicone oil
24 316 Stainless steel 316 Stainless steel Monel Silicone oil
25 316 Stainless steel 316 Stainless steel Tantalum Silicone oil
33 Hastelloy C Hastelloy C Hastelloy C Silicone oil
35 Hastelloy C Hastelloy C Tantalum Silicone oil
44 Monel Monel Monel Silicone oil
Code Shell material Conduit inlet dimensions
A Low copper aluminum alloy polyurethane coating M20×1.5
B Low copper aluminum alloy polyurethane coating 1/2-14 NPT
C Stainless steel M20×1.5
D Stainless steel 1/2-14 NPT
Code Pressure connection
L1 1/4NPT-18 Internal thread (excluding waist joint standard)
L2 1/2NPT-14 Internal thread
L3 M20×1.5 External thread
Code Optional parts
M4 LCD multi – power digital display head
B1 Pipe bending bracket
B2 Plate bending bracket
B3 Pipe mounting bracket
D0 The discharge valve is at the end
D1 The side discharge valve is on the upper part
D2 The side discharge valve is on the upper part
C02 M20 x 1.5 nut and Φ 14 pressure short tube
C12 1/2NPT-14 external thread and Φ14 pressure short tube
C22 1/4NPT-18 external thread and Φ14 pressure short tube
C32 1/4NPT-18 to M20×1.5 external thread
C42 1/2NPT-14 to M20×1.5 external thread
C43 1/2NPT-14 to 1/4NPT-18 internal thread
C44 1/2NPT-14 to 1/2NPT-14 external thread
C45 1/2NPT-14 to G1/2 external thread
X1 Oil ban
Gd Measure the gold-plated membrane box
Da Flameproof  ExdIIBT5Gb;(explosion-proof certificate no. : CE16.1163)
Fa Intrinsically safe ExiaIICT4 / T5 / T6Ga;(explosion-proof certificate no. : CE15.2354X)

Learn More About Capacitive-Absolute Pressure Transmitter

Absolute pressure transmitter is also a kind of pressure transmitter. However, the zero point of its starting pressure is absolute vacuum, and the pressure can be measured without internal vacuum at all. Absolute pressure transmitters are mainly suitable for measurement in cross-industry closed systems and places where altimeter measurement is required.

In the era of industrial automation, absolute pressure transmitters are widely used in:

  • Hydraulic and pneumatic control systems;
  • Petrochemical, environmental protection, air compression;
  • Power station operation inspection, locomotive braking system;
  • thermal power unit;
  • Light industry, mechanical metallurgy;
  • Building automation, constant pressure water supply system;
  • Other automation and detection systems;
  • Industrial process detection and control;
  • Laboratory pressure calibration, etc.

Speaking of the difference between absolute pressure transmitter and gauge pressure transmitter, you first understand the meaning of absolute pressure and gauge pressure.

Absolute pressure, or true pressure, is the pressure calculated from absolute zero pressure. Or the pressure calculated from the vacuum as the starting point. Absolute pressure, referred to as absolute pressure.

Gauge pressure, referred to as gauge pressure, refers to the pressure calculated from the local atmospheric pressure at that time. When the measured system pressure is equal to the local atmospheric pressure at that time, the pointer of the pressure gauge points to zero. That is, the gauge pressure is zero.

Vacuum degree, when the absolute pressure of the system being measured is less than the local atmospheric pressure at that time, the difference between the local atmospheric pressure and the absolute pressure of the system at that time is called the vacuum degree. The pressure measuring instrument used at this time is called a vacuum gauge.

Absolute pressure transmitter, we have explained above.
The gauge pressure transmitter is the most common pressure transmitter we often say.

The difference between absolute pressure transmitter and ordinary pressure transmitter

The scale of the starting point is different:
The starting point of an ordinary pressure transmitter, the zero point, is the pressure in the atmosphere. At this time, the bellows of the pressure transmitter is under the standard atmospheric pressure. , the output is 4ma.
The starting point for absolute pressure transmitters is absolute pressure. That is, the absolute pressure transmitter under atmospheric pressure displays the value of atmospheric pressure. The pressure at zero point 4ma at this time is absolute pressure zero.

The structure is different:
The diaphragm on the low pressure side of the absolute pressure transmitter is evacuated and has no air guide tube.
The low-pressure side diaphragm of ordinary pressure transmitters is directly in contact with the atmosphere, and usually has an air guide tube.

The measurement methods are different:
Ordinary pressure transmitters lead atmospheric pressure to one end of the pressure sensing element for comparison with the measured pressure. The difference between the two pressures is the measured pressure.
The pressure measured by the absolute pressure transmitter also needs to subtract the local atmospheric pressure.

If you cannot find an answer to your question in our SI-3151 Capacitive-Absolute Pressure Transmitter, you can always contact us and we will be with you shortly.

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More Featured Industrial Pressure Transmitters and Sensors

SI-3151 Capacitive-Absolute Pressure Transmitters

Sino-Inst is a manufacturer of Capacitive-Absolute Pressure Transmitters. SI-3151 Capacitive-Absolute Pressure Transmitters adopts high-performance pressure-sensing chips. With advanced circuit processing and temperature compensation technology, it converts pressure changes into linear current or voltage signals .

SI-3151 Capacitive-Absolute Pressure Transmitters have HART communication, communication and self-diagnosis functions. Users use handheld terminals or fieldbus systems to transmit, read, display and input all working information and additional information of transmitters from a long distance.

There are many types of pressure sensors, such as resistance strain gauge pressure sensors, semiconductor strain gauge pressure sensors, Silicon piezoresistive pressure sensors, inductive pressure sensors, capacitive pressure sensors, resonant pressure sensors and capacitive sensors.

A capacitive sensor is a device that converts the measured change into a change in capacitance, which itself is a variable capacitor. Because this sensor has the characteristics of simple structure, small size, good dynamic response, high sensitivity, high resolution, and non-contact measurement, it is widely used in displacement, acceleration, vibration, pressure, pressure difference, liquid level, etc. Sub-content and other detection fields.

If you need to purchase Capacitive-Absolute Pressure Transmitters, or have any technical questions about Absolute Pressure Transmitters, please feel free to contact our engineers.

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    SI-3151 Capacitive-Absolute Pressure Transmitter | Sino-Inst

    SI-3151 Absolute Pressure Transmitter is a capacitive pressure transmitter. It can be used not only for Absolute Pressure, but also for gauge pressure measurement.

    Product SKU: SI-3151 Capacitive-Absolute Pressure Transmitter

    Product Brand: Sino-Inst

    Product Currency: USD

    Product Price: 265

    Price Valid Until: 2039-09-09

    Product In-Stock: InStock

    Editor's Rating:
    5