Now due to social development, many industries are gradually adopting electronic pressure gauges, which are what we usually call pressure transmitters, but due to working environment, medium, medium temperature, etc., we must choose pressure transmitters Consider these issues. Now I will talk about the purchase of pressure transmitters.
First, the wetted material
What we have to consider is the medium measured by the pressure transmitter. The material of the general pressure transmitter that contacts the medium is 316 stainless steel. If your medium is not corrosive to 316 stainless steel, then basically all pressure changes The transmitters are suitable for your measurement of medium pressure.
If your medium is corrosive to 316 stainless steel, then we must use a chemical seal, which not only can measure the pressure of the medium, but also can effectively prevent the medium from contacting the wetted part of the pressure transmitter, thereby playing Protect the pressure transmitter and extend the life of the pressure transmitter.
Second, the accuracy level
Every electronic meter will have accuracy errors, but because the accuracy levels marked by different countries are different, for example, the accuracy of the national standards in China and the United States is the most linear part of the sensor, which is our usual The accuracy of the measurement range is between 10% and 90%; and the accuracy of the European standard is the worst part of linearity, which is what we usually call the measurement of 0 to 10% and 90% to 100% Accuracy between. If the accuracy of the European standard is 1%, the accuracy of the standard in China is 0.5%. The accuracy level of the pressure transmitter developed by Shanghai Yongwei Automatic Control Equipment Co., Ltd. is 0.2.
Third, range
The maximum range of general sensor measurement is 70% of the full range of the sensor, which is to measure the pressure of 70bar. The range of the pressure transmitter should be 100bar.
Fourth, output signal
At present, due to the needs of various acquisitions, there are many kinds of output signals of pressure transmitters on the market, mainly 4 ~ 20mA, 0 ~ 20mA, 0 ~ 10V, 0 ~ 5V, etc., but the more commonly used are 4 ~ 20mA and There are two kinds of 0 ~ 10V. Among the output signals I mentioned above, only 4 ~ 20mA is two-wire system (we say that the output is a few wire system without grounding or shielding wire), and the other is three-wire system.
Fifth, medium temperature
Since the signal of the pressure transmitter is partially converted through the electronic circuit, in general, the temperature of the measurement medium of the pressure transmitter is -30 to +100 degrees. If the temperature is too high, we generally use a condensate bend to cool Medium, so that the cost of letting the manufacturer to produce a high temperature pressure transmitter for you will be much lower.
Sixth, measuring medium
Generally, we measure relatively clean fluids. We just use a standard pressure transmitter. If the medium you measure is easy to crystallize or viscous, we generally use an external diaphragm. Or it can be used together with chemical seal, which will effectively prevent the medium from blocking the pressure measuring hole.
Seventh, other
After we determine the above five parameters, we must also confirm the process connection interface of your pressure transmitter and the power supply voltage of the pressure transmitter; if it is used in special occasions, we must also consider the explosion-proof and protection level