需的选型要依实际应用情况来选，这是主要的压力变送器选择原则。 The pressure transmitter needs to be selected according to the actual application situation, which is the main pressure transmitter selection principle. Because the environment in which pressure transmitters and pressure sensors are applied is generally harsh, accuracy and efficiency are easily affected by various factors. It can be said that no matter what instruments and meters play a pivotal role in the field of industrial automation. Therefore, in order to ensure the normal use of pressure transmitters, many factors need to be considered. A pressure transmitter is different from a sensor. In addition to being able to convert non-electrical power into measurable electrical power, the transmitter generally has a certain amplification effect. When selecting a pressure transmitter, you need to choose according to the specific application. First, determine the degree of corrosion of the measurement medium and the materials that can coexist. Select the appropriate transmitter based on the degree of corrosion. Generally speaking, non-strong acids and alkalis can use transmitters with stainless steel as the isolation unit, otherwise only Choose a special transmitter such as a titanium alloy designed for corrosion protection. The viscosity of the medium also affects the precise use of the pressure transmitter. Therefore, it is necessary to see whether the medium is viscous and clean. If it is very viscous, you need to select a transmitter with a rigid isolation unit. This can be determined according to whether the fluidity of the medium is slow. Determine the measurement range and measurement method of the pressure transmitter. Generally, when selecting the measurement range, the actual measurement range and the overpressure measurement range must be considered. The selection range is based on the maximum measurement range, and the size of the overpressure measurement range is also considered. In addition, you need to choose the correct measurement method. If you are measuring differential pressure, you must choose a differential pressure transmitter to determine the accuracy range and compensate the temperature range. Use the temperature range according to the lowest accuracy you need to measure. product.
受影响的因素很多，专业人员在选择的时候考虑的范围就比较多。 Pressure transmitters are affected by many factors, and professionals have more scope to consider when choosing. In addition to the options introduced, there is also the need to consider long-term stability indicators when selecting a pressure sensor. There are two temperature values here, one is the compensation temperature range, and the other is the use temperature range. The so-called compensation temperature range is the temperature range of the measuring medium during normal operation. The use temperature range is the maximum temperature range that may occur during use. Generally, the temperature range is slightly larger than the required temperature range. Determine pressure connections, electrical connections, mechanical dimensions, etc. Determine whether environmental protection is required for explosion protection, electromagnetic interference, and waterproofing of the enclosure. Again, the selection of the pressure transmitter depends on the actual application! In addition, the installation of the pressure transmitter is also very particular about. Non-professionals are better not to install at will. Improper installation will not only affect the actual efficiency of the pressure transmitter, but also damage the pressure transmitter.
用于测量液体、气体或蒸汽的液位、密度和压力，然后将压力信号转变成4～20mA DC信号输出。 The pressure transmitter is used to measure the level, density and pressure of liquid, gas or steam, and then convert the pressure signal into a 4-20mA DC signal output. Pressure transmitters mainly include capacitive pressure transmitters and diffused silicon pressure transmitters, ceramic pressure transmitters, and strain-type pressure transmitters. Pressure transmitters are divided into general pressure transmitters (0.001MPa ～ 20MPa), differential pressure transmitters (0 ～ 1.5kPa), and negative pressure transmitters. Three common problems in the use of pressure transformers:
(1) If the pressure goes up and the transmitter output doesn't go this way, you should first check whether the pressure interface is leaking or blocked. If it is not confirmed, check the wiring method. If the wiring is correct, check the power supply. Whether the sensor has an output at the zero position or simply pressurize to see if the output changes. If there is a change, the sensor is not damaged. If there is no change, the sensor is damaged.
Other reasons for this may be instrument damage, or problems in other parts of the entire system. The output of the pressure transmitter does not change, the output of the pressure transmitter changes suddenly, and the pressure relief transmitter cannot return to zero. The cause of this phenomenon is most likely caused by the pressure sensor seal ring, generally due to the seal ring specifications (too soft or too thick). When the sensor is tightened, the seal ring is compressed into the sensor pressure port to block the sensor and pressurize it. When the pressure medium cannot enter, but when the pressure is very high, the seal ring is suddenly opened, the pressure sensor changes under pressure, and when the pressure decreases again, the seal ring returns to block the pressure inlet, and the remaining pressure cannot be released, so The zero position of the sensor cannot be lowered again. The best way to eliminate this is to remove the sensor and directly check whether the zero position is normal. If the seal is replaced normally, try again.
There are several reasons for the unstable output signal of the transmitter:
A. The pressure source itself is an unstable pressure
B. Does the meter or pressure sensor have a strong anti-interference ability?
C. Insufficient sensor wiring
D. The sensor itself vibrates a lot
E. Sensor failure Possible reasons for the transmitter to fail to output when connected to power are:
F. Incorrect wiring (check the instrument and sensor)
G. Open or shorted wires
H. No power output or power mismatch
I. Instrument is damaged or mismatched
J. Sensor damage The deviation between the transmitter and the pointer pressure gauge is large