Basic introduction of pressure transmitter

Pressure transmitter is a commonly used sensor in industrial practice, which has a wide range of applications

Used in various industrial automation environments, involving water conservancy and hydropower, railway transportation, intelligent buildings, production automation, military industry, petrochemicals, oil wells, electricity, ships, machine tools, pipelines and many other industries.

There are two main types of pressure transmitters: electric and pneumatic. The unified output signal for electric motors is a DC signal ranging from 0 to 10mA, 4 to 20mA, or 1 to 5V. The unified output signal of pneumatic type is a gas pressure of 20-100Pa.

Pressure transmitters can be divided into force (torque) balance type, capacitance type, inductance type, strain type, and frequency type according to different conversion principles. Below is a brief introduction to the principles, structures, usage, maintenance, and calibration of several pressure (differential pressure) transmitters. [2] 

The main function of a pressure transmitter is to transmit pressure signals to electronic devices, and then display pressure on a computer. The principle is roughly to convert the mechanical signal of water pressure into electronic signals such as current (4-20mA). The pressure and voltage or current are linearly related, generally proportional. So, the voltage or current output by the transmitter is related to the pressure, and a relationship between pressure and voltage or current is obtained. The two pressures of the measured medium of the pressure transmitter are passed into the high and low pressure chambers, and the pressure in the low pressure chamber is atmospheric pressure or vacuum, acting on the isolation diaphragms on both sides of the δ element (i.e. component), and transmitted to both sides of the measuring diaphragm through the isolation diaphragms and the filling liquid inside the component.

A pressure transmitter is composed of a measuring diaphragm and an electrical capacitor on both sides of the insulating film. When the pressure on both sides is not consistent, it causes displacement of the measuring diaphragm, and the displacement is proportional to the pressure difference. Therefore, the capacitance on both sides is unequal, which is achieved through oscillation and demodulation.