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technical article
Selection and principle of pressure transmitter
2011-12-27 9:58:01

There are many principles of pressure transmitters. Different pressure transmitters have different principles. The above explains the principle of several commonly used pressure transmitter tasks.


原理,电容式压力变送器重要有完成压力/电容转换的容室敏感元件及将电容转换成二线制4-20mA电子线路板构成,当进程压力从从测量容室的两侧(或一侧) Capacitive pressure transmitter principle. Capacitive pressure transmitters are mainly composed of chamber sensitive components that complete pressure / capacitance conversion and electronic circuit boards that convert capacitance to two-wire 4-20mA. When the process pressure is measured from the measuring chamber, Both sides (or one side)

After being applied to the isolation diaphragm, it is transferred to the center of gravity diaphragm of the chamber through the silicone oil filling liquid. The center of gravity diaphragm is a diaphragm with a tight edge. Under the action of pressure, a corresponding displacement occurs. This displacement constitutes a differential capacitor. Changes, and undergoes conditioning, vibration, and shrinking of electronic circuit boards,

Converted into 4-20mA signal input, input current is inversely proportional to process pressure


Principle and application of dispersed silicon pressure transmitter


The pressure of the measured medium indirectly acts on the diaphragm of the sensor (stainless steel or ceramic), causing the diaphragm to undergo a micro-displacement inversely proportional to the pressure of the medium, causing the resistance value of the sensor to change, and detecting this change with electronic circuits, and Conversion input a corresponding

Due to the canonical measurement signal of this pressure.


Principle and Application of Ceramic Pressure Transmitter


The anti-corrosion pressure transmitter has no liquid transmission, and the pressure indirectly acts on the front surface of the ceramic diaphragm, causing a huge deformation of the diaphragm. The thick film resistor is printed on the reverse side of the ceramic diaphragm and connects to a Wheatstone bridge ( Closed bridge), due to the

The piezoresistive effect makes the bridge generate a voltage signal that is highly linear and inversely proportional to the pressure, and also inversely proportional to the encouraging voltage. The standard signal is calibrated to 2.0 / 3.0 / 3.3mV / V according to the pressure and air path. Strain sensors are compatible. Laser calibrated for sensing

It has high temperature stability and stability at all times. The sensor has a temperature compensation of 0 to 70 ° C, and can be indirectly in contact with most media. Ceramics are a proven material with high elasticity, corrosion resistance, abrasion resistance, shock resistance, and vibration. Thermal stability of ceramics and its thick film

The resistance can make its task temperature range up to -40 ~ 135 ° C, and it has high accuracy and high stability for measurement. Electrical insulation level> 2kV, strong input signal, good temporary stability. High-performance, low-cost ceramic sensors will be the development direction of pressure transmitters in Europe and the United States

There is a tendency to replace other types of sensors one-sidedly. In China, more and more players are using ceramic sensors to replace dispersed silicon pressure transmitters.


Sensors and transmitters play a pivotal role in the fields of instrumentation, instrumentation and industrial automation. Unlike sensors, in addition to being able to convert non-electrical power into measurable electrical power, the transmitter generally has a certain amplification effect.

: How to choose a pressure transmitter :


,否则只能选择专为防腐蚀设计的钛合金等特制变送器。 Determine the measurement medium, look at the corrosion degree of the measurement medium, and select the corresponding transmitter according to the degree of corrosion. Generally speaking, non-strong acids and alkalis can use transmitters with stainless steel as the isolation unit. Corrosion designed titanium alloy and other special transmitters.


Secondly, you need to see if the measuring medium is thick and clean. If it is very thick (such as very slow flow), you need to choose a transmitter with a rigid isolation unit.


Determine the measurement range and measurement method


Generally, when selecting the measurement range, you should consider the actual measurement range and overvoltage measurement range. The selection range is based on the maximum measurement range, and the size of the overvoltage measurement range is also considered.

In addition, the correct measurement method needs to be selected. If measuring differential pressure, a differential pressure transmitter must be selected.


Determine accuracy range, compensation temperature range, use temperature range


According to the minimum accuracy you need to measure, generally choose a product slightly higher than the required minimum accuracy.


At the same time, long-term stability indicators need to be considered when selecting


The so-called compensation temperature range is the temperature range of the measuring medium during normal operation. The use temperature range is the maximum temperature range that may occur during use. Generally, it is slightly larger than the required temperature range when selected.


Determine pressure interface, electrical interface, mechanical dimensions, etc.


Determine if environmental protection is required for explosion protection, electromagnetic interference, and enclosure waterproofing