Overview of pressure transmitter
Instrumentation is a device for measuring and testing substances in the world. Instrumentation is able to apply information technology to industrialized production, leading all kinds of industries to the forefront of the industry. Among them, pressure transmitter, as a kind of high-precision measuring instrument, has been widely used in thermal power, chemical industry, petroleum refining, bioengineering, steel, aerospace and other industrial fields. Therefore, it is of great significance to develop and produce pressure transmitters with high stability and high accuracy.
Overview of pressure transmitter
Due to the diverse output signals of the sensor, in order to enhance the versatility of the sensor in practical applications and simplify the transmission and recording of signals, usually requires a circuit to convert the output signal to a standard signal. Pressure transmitter is a fluid pressure sensor measurement signal into a standard signal device. Pressure transmitters are mainly categorized into adiabatic pressure transmitters, gauge pressure transmitters and differential pressure transmitters. Adiabatic pressure transmitters are used in applications where atmospheric pressure cannot affect the measurement process, such as vacuum distillation towers. Gauge pressure transmitters use atmospheric pressure instead of absolute vacuum and are used in a wider range of applications. Differential pressure transmitters, on the other hand, are used to measure pressure differences.
1.1 Pressure transmitter body structure
Currently the mainstream pressure transmitter is mainly composed of sensors, measurement cartridges and interface and processing circuitry of three major components. Pressure sensors and temperature sensors are sealed together in the top of the measuring diaphragm box, clamped by two sealing flange to form the measuring part of the transmitter, so that the field measurement of the pressure signal into an electrical signal. The electronic circuit board and liquid crystal display head and terminals constitute the interface and processing circuit, which is responsible for amplifying the electrical signal output from the sensor, analog-to-digital conversion, real-time display of data and output of standard signals.
1.2 Classification of pressure transmitter
The use of different measurement principles produced by the pressure transmitter, according to their respective operating principles can be divided into capacitive pressure transmitters, resonant pressure transmitters and monocrystalline silicon pressure transmitters and other types of pressure transmitters.
①Capacitive pressure transmitter
The working principle of capacitive pressure transmitter is that the fluid pressure difference is transferred to the internal metal capacitance pole plate through the medium. The plate produces a corresponding deformation, resulting in a change in capacitance. This change is processed through the circuit to get the pressure signal.
②Resonant pressure transmitter
The principle of resonant pressure transmitter is: diffusion silicon film in a certain pressure difference under the action of deformation, caused by the internal resonance beam frequency change; fluid pressure difference is transferred to the internal monocrystalline silicon resonance beam; resonance beam in the action of the pressure to produce a frequency signal corresponding to the frequency signal; frequency signals through the circuit processing to get and output pressure signals.
③Monocrystalline silicon pressure transmitter
The main structure of monocrystalline silicon pressure transmitter is a Wheatstone bridge. The external pressure difference is transmitted to the internal bridge through the medium. Due to the piezoresistive effect of the material, the bridge produces a resistance value that changes with the pressure. A pressure signal can be obtained by detecting the output of the bridge through a circuit. Monocrystalline silicon pressure transmitter has a high output sensitivity, large signal volume, very small return difference and circuit design is relatively simple and reliable and so on.
