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Digital pressure transmitter maintenance methods
Dec 21, 2017

Digital pressure controller with excellent stability of the pressure sensor as its sensitive components, to detect process pressure medium. Stainless steel interface with a variety of media compatible. Mainly used in petrochemical industry, coal mine hydraulic power station dam, automotive electronics, level measurement.

For everyone to share under the digital pressure transmitter routine maintenance of the seven methods.

1, check the mounting hole size: If the mounting hole size is inappropriate, the sensor during installation, the threaded portion is very vulnerable to wear. This will not only affect the sealing performance of the device, but also make the pressure sensor can not fully play its role, and may even have potential safety hazard. Only suitable mounting holes to avoid thread wear (Threaded Industry Standard 1 / 2-20 UNF 2B) can usually be measured with mounting hole gauges to make suitable adjustments.
2, to keep the installation hole cleaning: Keeping the installation hole cleaning and prevent the melt blockage to ensure the normal operation of the device is very important. Before the extruder is cleaned, all pressure sensors should be removed from the barrel to avoid damage. 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 reinstalled. Cleaning kits remove these melt residues. However, the repeated cleaning process may deepen the mounting hole damage to the sensor. If this happens, you should take steps to increase the sensor's position in the mounting hole.
3, choose the right location: When the pressure sensor installed too close to the upstream of the production line, the unmelted material may wear the top of the sensor; if the sensor is installed too far behind the position between the sensor and the screw stroke may There is a stagnant area of molten material where the melt may degrade and the pressure signal may also transmit distortion; if the sensor is too deep into the barrel, the screw may touch the top of the sensor during rotation causing damage. In general, the sensor can be located on the barrel in front of the screen, before or after the melt pump or in the mold.
4. Carefully clean; remove all sensors before cleaning the extruder barrel with a wire brush or special compound. Because these two kinds of cleaning methods may cause damage to the sensor diaphragm. When the barrel is heated, the sensor should also be removed and wiped off with a soft, non-abrasive cloth, and the sensor holes need to be cleaned with a clean drill and guide sleeve.
5, to keep dry: Although the sensor circuit design can withstand harsh extrusion processing environment, but most of the sensors can not be absolutely waterproof, in a humid environment is not conducive to normal operation. Therefore, there is a need to ensure that the water in the water cooling device of the extruder barrel will not leak, otherwise it will adversely affect the sensor. If the sensor has to be exposed to water or humid environment, it is necessary to choose a special sensor with strong water resistance.
6, to avoid low-temperature interference: In the extrusion process, for plastic raw materials, from solid to molten state should have sufficient "penetration time." If the extruder did not reach the operating temperature before it started production, both the sensor and the extruder would be damaged to some 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 sensor, make sure that the barrel temperature is high enough and the material inside the barrel is in a softened state.
7, Preventing Pressure Overloading: Even if the pressure sensor's load cell design is designed to overload up to 50% (beyond the maximum range), risk should be avoided from the point of view of the safety of the equipment, and it is best to select the measured pressure to be within the measuring range Sensor. Under normal circumstances, the optimal range of the selected sensor should be 2 times the measured pressure, so that the pressure sensor can be protected from damage even if the extruder is operated under extremely high pressure.

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