Generally speaking, the pressure transmitter is mainly composed of load cell sensor (also known as pressure sensor), measuring circuit and process connector. It can convert the physical pressure parameters such as gas and liquid sensed by the load cell sensor into standard electrical signals (such as 4 ~ 20mADC), so as to supply secondary instruments such as indicating alarm instrument, recorder and regulator for measurement, indication and process adjustment.
According to the measurement range, the pressure transmitter can be divided into general pressure transmitter (0.001mpa ~ 35MPa), micro differential pressure transmitter (0 ~ 1.5kpa) and negative pressure transmitter; From the perspective of accuracy, because the accuracy of China's national standard is 0.5% Therefore, in recent years, it can be divided into high-precision pressure transmitter (0.1% or 0.2% or 0.075%) and general pressure transmitter (0.5%)
According to the type of sensor, pressure transmitter can be divided into capacitive pressure transmitter, diffused silicon pressure transmitter and monocrystalline silicon pressure transmitter
The pressure transmitter transmits the pressure signal to the electronic equipment, and then displays the pressure on the computer.
The principle is as follows:
The mechanical signal of water pressure is transformed into electronic signal such as current (4-20mA)
Pressure has a linear relationship with voltage or current, which is generally proportional
Therefore, the voltage or current output by the transmitter increases with the increase of pressure
From this, a relationship between pressure and voltage or current is obtained
The two pressures of the measured medium of the pressure transmitter are connected to the high and low pressure chambers. The pressure of the low pressure chamber adopts atmospheric pressure or vacuum, acting on δ On the isolation diaphragms on both sides of the element (i.e. the sensitive element), it is transmitted to both sides of the measuring diaphragm through the figreth isolation diaphragm and the filling liquid in the element. The pressure transmitter is a capacitor composed of measuring diaphragm and electrodes on insulating sheets on both sides. When the pressures on both sides are inconsistent, the measuring diaphragm will be displaced, and its displacement is directly proportional to the pressure difference. Therefore, the capacitance on both sides is unequal, which is converted into a signal directly proportional to the pressure through oscillation and demodulation links.
