Differential pressure transmitters and pressure transmitters are all types of transmitters, except that one measures the pressure difference, and one directly measures the pressure, gauge or absolute pressure. Everyone usually hears the pressure transmitter. In fact, the differential pressure transmitter is also widely used. Today we explain how to properly maintain the differential pressure transmitter. Only the daily correct maintenance can guarantee the service life of the differential pressure transmitter. Even extended. The correct maintenance of the differential pressure transmitter is divided into 6 steps (this step is in no particular order, only all of which need to be noted).
1. Choose the right position: When the differential pressure transmitter is installed too close to the upstream of the line, the unmelted material will wear to the top of the sensor. If the sensor is installed too far behind, there will be a stagnation zone of molten material between the sensor and the screw stroke, where the melt is likely to degrade and the pressure signal may transmit distortion. In general, the sensor can be located on the barrel in front of the screen, in front of or behind the melt pump, or in the mold. I don't know if this counts, maybe this text doesn't need to be seen.
2. Check the size of the mounting hole: If the size of the mounting hole is not suitable, the threaded part of the differential pressure transmitter is more susceptible to certain wear during the installation process. This will not only directly affect the sealing of the equipment, but also make the pressure sensor not fully function, and may even pose a safety hazard. Only the proper mounting holes can avoid the wear of the threads. Usually we can use the mounting hole measuring instrument to carry out fine inspection of the mounting holes to make appropriate adjustments.
3. Avoid low temperature interference: In the extrusion production process, if the extruder does not reach the operating temperature before starting the production, the sensor and the extruder will be damaged to a certain extent. In addition, if the sensor is removed from the cold extruder, the material may stick to the top of the sensor causing damage to the diaphragm. Therefore, before removing the differential pressure transmitter, it should be confirmed that the temperature of the barrel is high enough and the material inside the barrel is softened. Low temperature interference should be understood by everyone. It is easy to understand this text.
4. Keep dry: Although the circuit design of the differential pressure transmitter can withstand the harsh extrusion processing environment, most of the sensors are not absolutely waterproof, and it is not suitable for normal operation in humid environments. Therefore, it is necessary to ensure that the water in the water-cooling device of the extruder barrel does not leak, which may adversely affect the sensor. If the sensor has to be exposed to water or moisture, choose a special sensor that is extremely water resistant.
5. Keep the mounting holes clean: Keep the mounting holes clean mainly to prevent the clogging of the melt, which is extremely important to ensure the normal operation of the equipment. All pressure sensors should be removed from the barrel to avoid damage before the extruder is cleaned. When the sensor is removed, the melt may flow into the mounting hole and harden. If the residual melt is not removed, the top of the sensor may be damaged when the sensor is mounted again. The cleaning kit removes these melt residues. However, repeated cleaning processes may deepen the damage to the sensor caused by the mounting holes. If this happens, steps should be taken to raise the position of the sensor in the mounting hole. The cleaning of the mounting holes is easier to understand, and the mounting holes can be easily cleaned with the control picture and structure drawing.
6. Careful and thorough cleaning: All differential pressure transmitters should be removed before cleaning the barrel of the extruder with a wire brush or special compound. Because both methods of cleaning may cause damage to the diaphragm of the sensor. When the barrel is heated, the sensor should also be removed and wiped with a soft cloth that does not wear out, and the sensor holes need to be cleaned with a clean drill and guide sleeve.
The above 6 steps look complicated and seem to have a lot of precautions, but it is still relatively simple to do. For example, in terms of cleaning, some process occasions are not so dirty after one year of use. Even if it is dirty, it is very easy to clean, because the structure of the differential pressure transmitter is not responsible, and the disassembly is relatively easy.