First of all, let's understand the structure and function of conventional pressure transmitters. The pressure transmitter is mainly composed of three parts: a pressure sensor, a measurement conversion circuit and a process connection component. Its function is to convert the physical pressure parameters such as gas and liquid felt by the pressure sensor into standard electrical signals, and supply them to display alarms, DCS systems, recorders, PLC systems, etc. for display, measurement, control and adjustment. In these jobs, many different problems may occur, and at this time, it is necessary to pay attention to the maintenance and protection of the pressure transmitter in the work.

Let's take a look at the precautions for specific pressure transmitters in use.

1. First of all, check whether there is signal interference around the pressure transmitter, and if so, try to eliminate it, or connect the sensor shield wire with the metal shell as much as possible to enhance the anti-interference ability.

2. The mounting holes should be cleaned regularly to ensure that the mounting holes are clean. Prevent the transmitter from coming into contact with corrosive or overheated media;

3. When wiring, pass the cable through the waterproof connector (accessory) or winding pipe and tighten the sealing nut tightly to prevent rainwater from leaking into the transmitter housing through the cable.

4. When measuring gas pressure, the pressure take-off should be open at the top of the process pipe, and the transmitter should also be installed in the upper part of the process pipe so that the accumulated liquid can be easily injected into the process pipe.

5. When measuring liquid pressure, the pressure tap should be opened on the side of the process pipe to avoid sedimentation.

6. Voltages higher than 36V should not be used on the pressure transmitter, which can easily lead to damage.

7. In the event of freezing in winter, the transmitter installed outdoors must take anti-freezing measures to prevent the liquid in the impulse port from expanding due to the freezing volume and causing damage to the sensor.

8. When measuring steam or other high-temperature media, it is necessary to connect a condenser such as a buffer tube (coil), and the operating temperature of the transmitter should not exceed the limit. In addition, the buffer tube needs to be filled with an appropriate amount of water to prevent the superheated steam from coming into contact with the transmitter. And the buffer heat pipe must not leak air.

Example of a pressure transmitter installation for measuring steam pipes

9. When measuring liquid pressure, the installation position of the transmitter should avoid the impact of the liquid (water hammer phenomenon) to avoid damage to the sensor due to overpressure.

10. The impulse pipe should be installed in a place with small temperature fluctuations;

11. Prevents the debris from being deposited in the catheter;

12. The medium measured by the pressure transmitter cannot freeze and freeze, and if it does, it can easily damage the diaphragm, which is generally very thin.