Seven selection rules for pressure transmitters

Pressure transmitter is a more commonly used field instrument in industrial practice. In electrical equipment, the pressure transmitter plays a function similar to the sensor, which can convert the physical pressure parameters such as gas and liquid felt by the pressure measuring element sensor into standard electrical signals (such as 4~20mA.DC, etc.). Use secondary instruments such as alarm, recorder and regulator for measurement, indication and process adjustment.

Pressure transmitters are widely used in various industrial automatic control environments. Since the pressure transmitter is a field instrument in direct contact with the measured medium, often working in high temperature, low temperature, corrosion, vibration, impact and other environments, the selection of the pressure transmitter, in addition to considering the measurement range and accuracy and other general instruments need to be considered, the working environment and the measured medium are also one of the important indicators. In general, regarding the selection of pressure transmitters, the following seven aspects should be noted:

1. According to the measured pressure range. In general, the actual measured pressure is selected according to 80% of the measured range. In general, the pressure transmitter pressure range max value should reach 1.5 times the system max pressure value. Some water pressure and process controls have pressure spikes or continuous pulses that can reach 5 or even 10 times the max pressure, causing damage to the transmitter.

2. According to the measured medium. According to the different measurement media, it can be divided into dry gas, gas liquid, highly corrosive liquid, viscous liquid, high temperature gas liquid, etc., according to the correct selection of different media, is conducive to extending the service life of the transmitter.

3. Level of accuracy as required. The measurement error of the transmitter is divided according to the accuracy level, and different accuracy corresponds to different basic error limits (expressed as percentage of the full-scale output).

4. According to the system operating temperature range. The measuring medium temperature should be within the working temperature range of the transmitter, such as excessive temperature use, will produce a large measurement error and affect the service life of the transmitter. In the case of high temperature, you can consider choosing a high temperature pressure transmitter or taking auxiliary cooling measures such as installing condensation tubes and radiators.

5. According to the measurement medium and contact. In some measuring occasions, the measuring medium is corrosive, at this time, it is necessary to choose a material compatible with the measuring medium or carry out special process treatment to ensure that the transmitter is not damaged.

6. According to the pressure interface form. Usually threaded connection (M20×1.5) is the standard interface form.

7. According to the power supply and output signal. Usually the pressure transmitter uses DC power supply to provide a variety of output signal options, including 4 ~ 20mA; 0 ~ 5V.DC, 1 ~ 5V.DC, 0 ~ 10mA.DC, etc., can have 232 or 485 digital output.