Classification of pressure transmitters:
　　
1. Gauge pressure transmitter:
　　
A gauge pressure transmitter is a pressure transmitter that uses local atmospheric pressure as the reference zero point.
　　
2. Pressure transmitter:
　　
A pressure transmitter is a type of pressure transmitter that uses vacuum degree as the reference zero point. During use, the reference zero point of the sensor can be automatically adjusted with the change of location and area without calibration. The appearance is identical to that of a gauge pressure transmitter.
　　
3. Differential pressure transmitter:
　　
A differential pressure transmitter is a pressure transmitter that measures the pressure difference between two pressure chambers. The differential pressure transmitter has two pressure chambers, "+" and "-", which respectively receive two pressures as comparison values. The end with the higher pressure is usually used as the "+" pressure chamber.
　　
Attention: When ordering a differential pressure sensor, please pay attention to one parameter of the differential pressure transmitter * - static pressure tolerance. For example, the differential pressure transmitter we use experiences a pressure of 10MPa at the "+" end during use
　　
The pressure on the pressure end is 10.5 MPa, so the differential pressure measured by the transmitter is 10.5-10=0.5 MPa
　　
The static pressure experienced by the transmitter is 10MPa. In the application process, the use of high static pressure and low differential pressure is not uncommon on site. The static pressure experienced by the ordered differential pressure transmitter should not exceed the tolerance static pressure value of the differential pressure transmitter, otherwise it is easy to be damaged.
　　
4. Input/insertion type liquid level transmitter:
　　
Liquid level transmitters are divided into two types: input type and insertion type, both of which are identical and convert the pressure received into liquid depth. When the water depth is 1m, the pressure on the transmitter is 10KPa. When ordering this type of sensor, please note:
　　
1. The measured liquid density should be communicated to the production unit.
　　
When the measuring medium is corrosive, the production unit should be informed.
　　
3. Notify the production unit when the measured medium temperature exceeds -10 ℃ and 60 ℃.
　　
5. Medium and high temperature pressure transmitter:
　　
For measuring high environmental temperatures or medium temperatures on site, it is necessary to use a medium high temperature pressure transmitter. This transmitter has good zero temperature coefficient and sensitivity temperature coefficient, and can ensure measurement accuracy in high temperature environments. When ordering this type of transmitter, it is necessary to inform the measuring medium temperature and ambient temperature for the convenience of the manufacturer to respond reasonably.