Pressure transmitter is used to measure the liquid level, density and pressure of liquid, gas or steam, and then convert the pressure signal into 4-20mADC signal output. There are mainly capacitive pressure transmitters and diffusion silicon pressure transmitters, ceramic pressure transmitters, strain type pressure transmitters and so on.
Capacitive
Pressure transmitter is the most commonly used sensor in industrial applications. It is widely used in many industries such as water conservancy and hydropower, railway transportation, intelligent buildings, production automation, aerospace, military industry, petrochemical, oil wells, power, ships, machine tools, pipelines and so on.
When the pressure acts directly on the surface of the measuring diaphragm, causing a slight deformation of the diaphragm, the high-precision circuit on the measuring diaphragm transforms this tiny deformation into a highly linear voltage proportional to the pressure and a voltage proportional to the excitation voltage Signal, and then use a dedicated chip to convert this voltage signal into an industry standard 4-2OmA current signal or 1-5V voltage signal.
Because the measuring diaphragm adopts standard integrated circuits, which contains linear and temperature compensation circuits, it can achieve high precision and high stability. The transmission circuit uses a dedicated two-wire chip to ensure the output of two-wire 4-2OmA current. Signal, convenient for field wiring.
Diffused silicon
The pressure of the measured medium directly acts on the diaphragm of the sensor (stainless steel or ceramic), causing the diaphragm to generate a micro-displacement proportional to the pressure of the medium, causing the resistance value of the sensor to change, and detecting this change with an electronic circuit, and The conversion outputs a standard measurement signal corresponding to this pressure.
ceramics
The pressure acts directly on the front surface of the ceramic diaphragm, causing a slight deformation of the diaphragm. The thick film resistor is printed on the back of the ceramic diaphragm and connected into a Wheatstone bridge (closed bridge). Due to the piezoresistive effect of the varistor , So that the bridge generates a highly linear voltage signal proportional to the pressure and proportional to the excitation voltage.
Strain gauge
The resistance strain gauge is a sensitive device that converts the strain change on the test piece into an electrical signal. It is one of the main components of piezoresistive strain transmitter. The most widely used resistance strain gauges are metal resistance strain gauges and semiconductor strain gauges. There are two types of metal resistance strain gauges: filament strain gauges and metal foil strain gauges. Usually, the strain gauges are tightly bonded to the substrate that generates mechanical strain through a special adhesive. When the stress of the substrate changes, the resistance strain gauge also deforms together, causing the resistance of the strain gauge to change, so that The voltage applied to the resistor changes.