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The working principle of a pressure transmitter can be described as follows: The two pressures of the medium being measured are introduced into the high and low pressure chambers, acting on the diaphragms on either side of the δ element (i.e., the sensitive element). These pressures are then transmitted to both sides of the measurement diaphragm through the diaphragms and the filling fluid inside the element. The measuring diaphragm and the electrodes on the insulating pieces on both sides each form a capacitor. When the pressures on both sides are not equal, this causes the measuring diaphragm to move; the amount of displacement is proportional to the pressure difference. As a result, the capacitances on both sides become unequal. Through oscillation and demodulation processes, this is converted into a signal that is proportional to the pressure. The working principle of pressure transmitters and absolute pressure transmitters is the same as that of differential pressure transmitters; the difference is that the pressure in the low-pressure chamber is atmospheric pressure or vacuum. I. Proper Use of Pressure Transmitters Prevent pressure transmitters from coming into contact with corrosive or overheated media ； Prevent residue from accumulating inside the conduit during use ； When measuring liquid pressure, the pressure tapping should be located on the side of the process pipeline to avoid sediment accumulation ； When measuring gas pressure, the pressure tap should be located at the top of the process pipeline, and the pressure transmitter should also be installed in the upper part of the pipeline, so that any accumulated liquid can easily flow into the pipeline ； The pressure guiding tube of the transmitter should be installed in a location with minimal temperature fluctuations ； When measuring steam or other high-temperature media, a condenser such as a buffer tube (coil) must be used to prevent the operating temperature of the transmitter from exceeding its limits ； During freezing in winter, transmitters installed outdoors must be equipped with anti-freezing measures to prevent the liquid in the pressure tap from expanding due to freezing, which could otherwise cause damage to the sensor ； When measuring liquid pressure, the installation location of the pressure transmitter should be such that it is protected from liquid impacts (water hammer effect), to prevent the transmitter from being damaged due to excessive pressure ； When making the connections, pass the cable through the waterproof connector or flexible tube and tighten the sealing nut to prevent rainwater and other substances from seeping into the transmitter housing via the cable. II. Daily Maintenance of Pressure Transmitters 1. Check the dimensions of the mounting hole. If the dimensions of the mounting hole are not appropriate, the threaded part of the sensor is prone to wear during installation. This not only affects the sealing performance of the equipment, but also prevents the pressure sensor from functioning properly; it may even pose safety hazards. Only appropriate mounting holes can prevent thread wear (thread industry standard 1/2-20 UNF 2B); typically, a mounting hole gauge can be used to inspect the holes in order to make the necessary adjustments. 2. Keep the mounting holes clean. It is very important to keep the mounting holes clean and prevent them from being blocked by molten material in order to ensure the proper operation of the equipment. Before the extruder is cleaned, all pressure sensors should be removed from the barrel to avoid damage. When removing the sensor, molten material may flow into the mounting hole and harden; if this residual molten material is not removed, it may cause damage to the top of the sensor when it is installed again. The cleaning kit can remove these melt residues. However, repeated cleaning processes may exacerbate the damage caused to the sensor by the mounting holes. If this happens, measures should be taken to raise the position of the sensor within the mounting hole. 3. Choose the appropriate location: If the pressure sensor is installed too close to the upstream part of the production line, unmelted material may wear out the top of the sensor ； If the sensor is installed too far back, a stagnant area of molten material may form between the sensor and the screw’s travel distance; there, the melt can degrade, and the pressure signals may be transmitted inaccurately ； If the sensor is too deep inside the barrel, the screw may come into contact with the top of the sensor during rotation, causing damage to it. Generally, sensors can be located on the barrel in front of the filter screen, before and after the melt pump, or inside the mold. 4. Thorough cleaning: Before using a wire brush or special compounds to clean the extruder barrel, all sensors should be removed. Because both of these cleaning methods can potentially damage the diaphragm of the sensor. When the barrel is heated, the sensor should also be removed, and its top surface should be wiped with a soft cloth that does not cause wear; meanwhile, the holes in the sensor need to be cleaned using a clean drilling machine and guide sleeves. 5. Keep it dry. Although the circuit design of pressure transmitter sensors can withstand harsh extrusion processing conditions, most sensors are not completely waterproof, and they do not function properly in humid environments. Therefore, it is necessary to ensure that water in the water-cooling system of the extruder barrel does not leak, as this could have an adverse effect on the sensors. If the sensor has to be exposed to water or humid environments, special sensors with excellent waterproof properties must be chosen. 6. Avoid interference from low temperatures: During the extrusion process, plastic raw materials need sufficient \"soak time\" to transition from a solid state to a molten state. If the extruder has not reached its operating temperature before starting production, both the sensor and the extruder will suffer some degree of damage. Furthermore, if the sensor is removed from a cold extruder, the material may stick to the top of the sensor and cause damage to the diaphragm. Therefore, before removing the sensor, it is necessary to ensure that the temperature of the barrel is high enough and that the material inside the barrel is in a softened state. 7. Preventing pressure overload: Even though the overload rating of the pressure transducer sensors allows for up to 50% excess over the maximum measurement range, it is still advisable to avoid taking risks from a safety perspective regarding equipment operation; it is best to use sensors whose measured pressure falls within the specified range. Under normal circumstances, the optimal range of the selected sensor should be twice the pressure to be measured, so as to prevent the pressure sensor from being damaged even when the extruder operates at extremely high pressures. Pressure transmitters need to be checked once a week and once a month; the main tasks are to remove dust from the device, carefully inspect the electrical components, and regularly calibrate the output current value. Since there is low-voltage electricity inside the pressure transmitter, it must be separated from external high-voltage electricity. For more information, please visit the company’s official website at http://www.yb1518.com/. Please retain this link when reproducing the content! http://www.yb1518.com/UploadFiles/2010728142026546.jpg