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08 2025
Melt Pressure Sensor Maintenance and Calibration
The use of melt pressure sensors in plastic extrusion and film production lines is fundamental to process stability and product quality. Accurate pressure measurement, especially in systems powered by gear pumps, ensures the safe and efficient operation of both pumps and line components. Therefore, pressure sensors must undergo regular maintenance and calibration.
Regular Maintenance and Calibration Steps
Annual sensor calibration: Verification should be performed using dry bench tests or in-process references. This is a critical step to maintain measurement accuracy over time.
Cleaning the sensor diaphragm: Carbonized residue, common in melt polymers, can accumulate on the diaphragm surface and cause measurement errors. Regular cleaning extends sensor life.
Correct installation torque: The torque values specified by the manufacturer must be adhered to during sensor installation; otherwise, sealing problems and sensor failures may occur.
Cable shielding and grounding: Cables must be shielded and properly grounded to prevent electrical interference from frequency converters.
Application Example: Extruder – Gear Pump Scenario
Line Configuration: 120 mm single-screw extruder + 0.8 L/Rev gear pump, capacity 300 kg/h.
Material: 30% recycled PE blend.
Target Pressure: Pump inlet pressure 120 bar.
Results: With PID control parameters (P=1.2, I=4.5 s, D=0), inlet pressure fluctuation was reduced from ±7 bar to ±1.2 bar. Film thickness variation was reduced from ±4% to ±1.5%.
This example clearly demonstrates how correctly selecting and maintaining melt pressure sensors can significantly improve process quality. By ensuring sensor calibration, both energy efficiency and product standardization are increased in film and sheet production.