In addition, measuring the pressure through the filter screen and the melt pump is also very important for ensuring the safety of production and optimizing the performance of the equipment. If the melt is blocked when flowing into the mold, the sensor downstream of the filter will give an alarm to alert the operator. When the sensor before the filter screen sends an alarm, it indicates that the internal pressure of the extruder is too high, which may cause excessive wear on the screw. For manufacturers using melt pumps, it is necessary to measure the inlet pressure and outlet pressure of the melt to ensure that the melt can continuously flow into the mold, because any obstruction may cause damage to the melt pump.

The common measurement for high temperature pressure measurement is to use capillary to reduce the temperature. Such as pressure measurement of high temperature steam or pressure measurement of high temperature oil. This way is not suitable for high-temperature melt media, because the high-temperature melt will become solid in the capillary due to the decreased temperature and then cannot transmit pressure. Therefore, the pressure measurement of high temperature melt must be direct pressure measurement. This is a big challenge for melt pressure transducers. The temperature of the high temperature melt can reach 300 degrees, 400 degrees or even higher, and the material of the wetted part needs special treatment. The key is that the liquid used to transmit the pressure after the diaphragm requires special material. The filling oil of ordinary diaphragm pressure transmitters is completely unable to adapt to such high temperatures. The Gefran melt pressure transducer M series is filled with high-purity mercury, and uses a special filling process to reduce the interference of impurities and air to achieve good stability. It can accurately transmit the pressure at different temperatures to achieve good linearity of pressure measurement.

Gefran also provides W series high-temperature melt pressure transducers with direct safety synthetic oil for applications requiring no mercury. The maximum temperature resistance of synthetic oil filling is 350 degrees Celsius. For higher temperature occasions, you need to choose K series high temperature melt pressure transducers with NaK filling fluid. K series products can stand temperatures up to 538 degrees Celsius, and fully comply with the European ROHS safety directive requirements.
High temperature melt pressure transducers are very sensitive components, especially diaphragms. Do not remove the protective cap until the installation is ready. During the installation process, attention should also be paid to the protection of the diaphragm.

Gefran melt pressure transducer is sealed in the form of a cone seal. The professional drilling tools to process the mounting holes and threads are required, use a closed shaft to ensure that they meet the requirements. At the same time, pay special attention to the coaxiality of the mounting holes and threads. If the coaxiality exceeds 0.2mm, the sensor will be damaged during installation. It is also necessary to ensure that the installed sensor diaphragm does not protrude from the inner wall of the chamber, and the depth of the recess must be less 0.2mm; protrusions will cause the diaphragm to be damaged sooner, and too deep recesses will also increase the chance of accidental damage to the diaphragm.

Before installing the sensor for the first time and before installing the sensor again after cleaning the barrel, you must use professional tools to clean the mounting hole to ensure that there is no residue in the mounting hole. It is recommended to use a torque wrench to install the sensor. The tightening torque is 13.6Nm, and the maximum should not exceed 50 Nm.