In the application of instrumentation, under normal circumstances, the use of transmitters is the most extensive and common, which is roughly divided into pressure transmitters and differential pressure transmitters. Transmitters are often used to measure pressure, differential pressure, vacuum, liquid level, etc.
Transmitters are divided into two-wire system (current signal) and three-wire system (voltage signal). Two-wire (current signal) transmitters are especially common; there are intelligent and non-intelligent ones, and more and more intelligent transmitters; in addition , According to the application, there are intrinsically safe type and explosion-proof type; when selecting the type, you should make the corresponding choice according to your own needs.
1. Compatibility of the tested medium
When selecting the type, consider the influence of the medium on the pressure interface and sensitive components, otherwise the outer diaphragm will be corroded in a short time during use, which may cause corrosion to the equipment and personal safety, so the choice of material is very important .
2. The influence of medium temperature and ambient temperature on the product
The temperature of the measured medium and the ambient temperature should be considered when selecting the model. If the temperature is higher than the temperature compensation of the product itself, it is easy to cause the product measurement data to drift. The transmitter must be selected according to the actual working environment to avoid the temperature causing the pressure-sensitive core. The measurement is inaccurate.
3. Selection of pressure range
The pressure rating of the pressure transmitter must match the pressure rating of the device when it is working.
4. the selection of pressure interface
In the selection process, the appropriate thread size should be selected according to the pressure port size of the actual equipment used;
5. Selection of electrical interface
When selecting the model, it is necessary to confirm the use of signal acquisition methods and on-site wiring conditions. The sensor signal must be connected to the user acquisition interface; select the pressure sensor with the correct electrical interface and signal method.
6. Pressure type selection
An instrument that measures absolute pressure is called an absolute pressure gauge. For ordinary industrial pressure gauges, the gauge pressure is measured, that is, the pressure difference between absolute pressure and atmospheric pressure. When the absolute pressure is greater than the atmospheric pressure, the measured gauge pressure is positive, called positive gauge pressure; when the absolute pressure is less than the atmospheric pressure, the measured gauge pressure is negative, called negative gauge pressure, that is, the degree of vacuum. The instrument that measures the degree of vacuum is called a vacuum gauge.
Post time: Dec-31-2021