In modern industrial processes, the most used pressure measurement scheme is the pressure transmitter that converts pressure into an electrical signal. But how do pressure transmitters convert pressure signals into electrical signals? Today we introduce five different conversion methods commonly used. Method 1: piezoelectric pressure transmitter Piezoelectric pressure transmitters are mainly based on the piezoelectric effect (Piezoelectric effect), using electrical components and other machinery to convert the pressure to be measured into electricity, and then carry out related measurement work measurement precision instruments. Piezoelectric transmitters cannot be used in static measurements, because the charge after being subjected to external forces can only be preserved when the loop has an infinite input resistance. But that’s not actually the case. Therefore, piezoelectric sensors can only be used for dynamic measurement. Its main piezoelectric materials are: dihydrogen amine phosphate, potassium sodium tartrate and quartz. The piezoelectric effect is found on quartz. Method 2: piezoresistive pressure transmitter Piezoresistive pressure transmitters are mainly based on the piezoresistive effect. The piezoresistive effect is used to describe the change in resistance of a material under mechanical stress. Unlike the piezoelectric effect described above, the piezoresistive effect only produces impedance changes and does not generate an electric charge. Piezoresistive pressure transmitters are typically threaded into Wheatstone bridges. Usually the sensitive core has no applied pressure, the bridge is in a balanced state (called the zero position), when the chip resistance changes after the sensor is pressed, the bridge will be out of balance. If a constant current or voltage supply is added to the bridge, the bridge will output a voltage signal corresponding to the pressure, so that the resistance change of the sensor is converted into a pressure signal output through the bridge. The bridge detects the change of resistance value, amplification, and then through the conversion of voltage and current, converted into the corresponding current signal, the current signal is compensated by the nonlinear correction loop, that is, the input voltage linear correspondence of 4~20mA standard output signal. In order to reduce the influence of temperature changes on the resistance value of the core and improve the measurement accuracy, the pressure transmitter adopts temperature compensation measures to keep its technical indicators such as zero drift, sensitivity, linearity, and stability at a high level. Method 3: Capacitive pressure transmitter A capacitive pressure transmitter is a pressure transmitter that uses capacitance as a sensitive element to convert the measured pressure into a changed capacitance value. This kind of pressure transmitter generally uses a round metal film or a metal plated film as an electrode of the capacitor, when the film feels pressure and deformed, the capacitance formed between the film and the fixed electrode changes, and the electrical signal that has a certain relationship with the voltage can be output through the measurement circuit. Capacitive pressure sensors belong to polar pitch variable capacitive sensors, which can be divided into single capacitive pressure transmitters and differential capacitive pressure transmitters. Method 4: Inductive pressure transmitter The working principle of inductive pressure transmitter is due to the difference in magnetic material and magnetic permeability, when the pressure acts on the diaphragm, the size of the air gap changes, the change of air gap affects the change of coil inductance, the processing circuit can convert the change of this inductance into the corresponding signal output, so as to achieve the purpose of measuring pressure. This kind of pressure sensor can be divided into two types according to the change of magnetic circuit: variable magnetoresistive and variable magnetic conductivity. The advantages of inductive pressure sensors are high sensitivity and large measuring range; The disadvantage is that it cannot be applied to high-frequency dynamic environments. Method 5: Vibrating string pressure transmitter Vibrating string pressure transmitter belongs to frequency sensitive transmitter, the sensitive element of vibrating string pressure transmitter is a taut steel string, and the natural frequency of the sensitive element is related to the size of the tensile force. The length of the string is fixed, and the amount of vibration frequency change of the string can be used to measure the magnitude of the tensile force, that is, the input is a force signal and the output is a frequency signal. The vibrating string pressure transmitter is divided into two parts, the upper and lower parts, and the lower components are mainly sensitive component combinations. The upper component is an aluminum shell, which contains an electronic module and a terminal block, which is placed in two chambers so that the tightness of the electronic module room is not affected when wiring. Among them, piezoresistive pressure transmitters are the main direction of the development of pressure transmitters at home and abroad. The piezoresistive pressure transmitter has strong anti-interference ability, small zero point drift, simple structure, high resolution, stable performance, convenient data transmission, processing and storage, and easy to realize the characteristics of instrument digitization. If you have any questions, welcome to call: 400-600-4496, please indicate from the official website of Star Meter Manufacturing Co., Ltd