Pressure transmitter is one of the most widely used sensors in industry. It is widely used in environment, petroleum, metallurgy, power, food, paper, medicine, machinery manufacturing, water conservancy and hydropower, production automation and other industries in chemical industry. The design and manufacture of pressure transmitter has formed certain industry standards.

The 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. It refers to the pressure sensor whose output is the standard signal, and it is an instrument that accepts the pressure variable to be converted into the standard output signal in proportion. It can transform the physical pressure parameters such as gas and liquid sensed by the pressure sensor into standard electrical signals (such as 4 ~ 20mADC, etc.), and supply the secondary instruments such as indicator alarm, recorder and regulator for measurement, indication and process adjustment. With reliable operation, stable performance, convenient installation and use, small volume, light weight, high performance price ratio, it can be widely used in various positive and negative pressure measurement.

Advantages of pressure transmitter:

1. The pressure transmitter is characterized by reliable operation and stable performance;

2. Special V / I integrated circuit, less peripheral devices, high reliability, simple and easy maintenance, small volume, light weight, extremely convenient installation and debugging;

3. Aluminum alloy die-casting shell, three end isolation, electrostatic spray protection layer, strong and durable;

4. 4-20madc two-wire signal transmission, strong anti-interference ability and long transmission distance;

5. Led, LCD and pointer are three kinds of indicator heads, which are very convenient to read on site. It can be used to measure viscous, crystalline and corrosive media;

6. High accuracy and stability. In addition to the imported original sensor has been corrected by laser, the comprehensive temperature drift and nonlinearity of the whole machine in the use temperature range are precisely compensated.

7. The tested medium is widely used, which can measure oil, water and paste compatible with 316 stainless steel and 304 stainless steel, with certain anti-corrosion ability;

8. High accuracy, high stability, imported original sensor, good linearity, high temperature stability;

9. Small volume, light weight, convenient installation, commissioning and use;

10. Stainless steel fully enclosed shell, good waterproof;

11. The pressure sensor directly senses the measured liquid level pressure, which is not affected by medium foaming and deposition.

Pressure transmitter users often have some common failures in the process of application, so how to solve the problems quickly without affecting production?

If the pressure goes up, the output of the transmitter will not go up: in this case, check whether the pressure interface leaks or is blocked, if it is normal. Check the wiring mode, if the wiring is correct. Next, check the power supply, for example, the power supply is normal. Please check whether there is output at the zero position of the sensor, or simply pressurize to see whether there is any change in the output. There is a change to prove that the sensor is not damaged, if there is no change to confirm the damage of the sensor. Other reasons for this may also be instrument damage (such as PLC range setting problems, etc.).

The output of the pressure transmitter does not change, the output of the re pressure transmitter changes suddenly, and the zero position of the pressure relief transmitter cannot return. This may be caused by the sealing ring of the pressure sensor. Generally, it is due to the specification of the seal ring (too soft or too thick). When the sensor is tightened, the seal ring is compressed into the pressure tap of the sensor to block the sensor. When the pressure is high, the pressure medium cannot enter. But when the pressure is high, the seal ring suddenly bursts open, and the pressure sensor changes due to the pressure. When the pressure decreases again, the seal ring will return to its original position to block the pressure tap, and the residual pressure will not be released Therefore, the zero position of the sensor cannot be lowered. The best way to eliminate this is to remove the sensor and directly check whether the zero position is normal. If it is normal, replace the appropriate sealing ring and try again.

The output signal of the pressure transmitter is unstable. The causes of the failure are as follows:

1. The sensor vibrates severely due to the vibration at the installation position

2. The anti-interference ability of instrument or pressure sensor is not strong

3. The pressure source itself is an unstable pressure

4. Sensor wiring is not firm

5. Sensor failure

There is no output when the transmitter is powered on, and the causes of the failure are as follows:

1. Wrong wiring (check the secondary instrument and sensor at the same time)

2. No power output or power mismatch

3. Open circuit or short circuit of conductor itself

4. Instrument damage or instrument mismatch

Sensor damage: the comparison deviation between the transmitter and the pointer pressure gauge is large. First, the deviation is normal. Second, confirm the normal deviation range. Method to confirm the normal error range: calculate the error value of the pressure gauge. For example, the range of the pressure gauge is 30 bar, the accuracy is 1.5%, and the minimum scale is 0.2 bar. The normal error is 30 bar * 1.5% + 0.2 * 0.5 (visual error) = 0.55 bar

The above are the common fault problems and solutions in the introduction and application of pressure transmitter. At present, pressure transmitter is widely used, almost penetrated into various industries, and more and more integrated with other measurement transmitters to form measurement and control system, which can improve the operation speed and efficiency in process control and factory automation. The market demand for pressure transmitters is growing, because they can work in extremely harsh environment, and only need a little maintenance, and have little impact on the surrounding environment.