Principle, classification and selection method of pressure transmitter

Pressure transmitter is a sensor device widely used in automatic control systems to measure pressure. It realizes control and feedback of the measured medium by converting the measured pressure into a standard electrical signal. The following will introduce the principle, classification and selection method of pressure transmitter in detail.

1. Principle

Pressure transmitter mainly adopts two methods, namely capacitive and strain type.

Capacitive pressure transmitter utilizes the change in capacitance caused by the change in the distance between the plates caused by the increase or decrease of the measured physical quantity such as pressure, force and mass of the air medium between the two plates of the capacitor. Within the measurement range, the mechanical type of measured physical quantity can be converted into a standard electrical signal output.

Strain type pressure transmitter applies the resistance strain principle to the symmetrical instrument of the pressure sensor. It mostly uses silicon wafers, mingmoisture tubes and metal film resistors and other components. By applying the pressure of the measured medium to the flexible material, it causes displacement, and then changes its strain, causing changes in resistance, so that it acts on the circuit and the output is converted into an electrical signal.

2. Classification

1. According to the structure: leaf spring type, belt type, flexure front type, silicon piezoresistive type, stiffness piezoresistive type, eutectic piezoresistive type, etc.

2. According to the use environment: general pressure transmitter, high temperature pressure transmitter, explosion-proof pressure transmitter, corrosion-resistant pressure transmitter, vibration-resistant pressure transmitter, etc.

3. According to the purpose of measurement: differential pressure type, absolute pressure type, vacuum type, liquid level type, gas pressure type, etc.

3. Selection method

1. Measuring range: A pressure transmitter with a measuring range that is the same as or slightly larger than the pressure of the measured medium should be selected.

2. Accuracy level: The selection should be based on the accuracy level of the required measurement. Generally speaking, a higher accuracy pressure transmitter should be selected.

3. Output signal: The output signal is selected according to the characteristics of the measured medium, usually 4-20mA DC signal, 0-10V DC signal, etc.

4. Use environment: It is necessary to select a suitable pressure transmitter that is resistant to high temperature, corrosion, vibration, explosion and other special environments.

5. Installation method: It is best to choose a pressure transmitter that is easy to install and not prone to failure.

In short, the selection of pressure transmitters should be based on the characteristics of the measured medium, the use environment, the accuracy level, the measurement range and other factors. Only by selecting products reasonably can the best effect be achieved and the accuracy and efficiency of automated control be improved.