The output signal of the pressure transmitter 4-20ma has a given continuous functional relationship (usually a linear function) with the pressure variable. In order to ensure that the transmitter selected by the customer meets the requirements of the site, there are several points to pay attention to when selecting the transmitter.

1,The type of pressure measurement: pressure types mainly include gauge pressure, absolute pressure, differential pressure, etc.; Gauge pressure refers to the atmospheric pressure as the basis, less than or greater than the atmospheric pressure; Absolute pressure refers to the pressure higher than the positive pressure zero based on the positive pressure zero. Differential pressure is the difference between two pressures.

2, Accuracy level: the measurement error of the transmitter is divided according to the accuracy level, and in the actual use process, it is selected according to the demand for measurement error and in line with the principle of applicable economy.

3, The limit overload of the system: the limit overload of the system should be less than the overload maintenance limit of the transmitter, otherwise it will affect the service life of the product and even damage the product.

4, Measuring range: generally according to the actual measured pressure for the measurement range of 80% selection.

5, The working temperature scale: the temperature of the measuring medium should be maintained within the temperature range that the pressure transmitter can work normally, if the temperature exceeds the applicable range, the error will become large and the service life of the instrument will be shortened accordingly; In the production process of the ip65 pressure transmitter, the temperature effect will be measured and compensated to ensure that the measurement error caused by the temperature of the product is within the range of accuracy requirements. In the case of high temperature, you can think about selecting a high temperature pressure transmitter or adopting a device condensing tube (device), radiator and other auxiliary cooling methods.

6, The compatibility of measuring media and touch raw materials: in some application locations, because the measuring media is corrosive, it is necessary to choose data compatible with the measuring media or special process treatment at this time to ensure that the transmitter is not damaged.

7, Pressure interface method: Usually the product to thread connection (M20×1.5) as the standard interface method.

8, Power supply and output signal: usually 24V power supply, output signal contains 4 ~ 20mADC, 0 ~ 5VDC, 1 ~ 5VDC, 0 ~ 10VDC and so on. The selection of pressure transmitter is mainly based on the type of measurement pressure, accuracy level, measurement range and other angles to consider, determine the manufacturer and model of the transmitter used, according to the use of requirements to determine the range of the transmitter. Range selection should follow the range up and down adjustable, accurate precision, suitable price and other principles of comprehensive consideration.