04
11 2020
Melt Pressure Sensor Technical Information
MPS Melt Pressure engineers have over 7 years of experience solving technical problems in the harshest environments for plastic melt pressure sensors and instrumentation. We have experienced almost every problem that could be encountered and we use this extensive knowledge base to assist all our existing customers.
This page contains answers to most of the common application FAQs our customers ask. Topics covered:
New Melt Pressure Transducer Installation Instructions
A. Transducer / Transmitter Tip Options
• Most applications: choose the Inconel diaphragm.
• Abrasive applications (materials that produce abrasive acids): choose a thread and diaphragm made of Hastelloy.
• Abrasive materials (such as glass-filled nylon): choose D-TiAIN end coatings
B. Hole Area
The best location to mount your converter is in front of the screw where the polymer is in a good molten state and shear stress is minimized. For reclaimed extrusion lines, care should be taken to place the converter far enough from the chamber to allow all pellets to melt, as the partially melted pellets can damage the tip.
Transducer enclosures should be installed in a location where temperatures will not exceed 150 ° F.
Care must be taken if the transducer is mounted above the extruder. Heat rises and heats the enclosure. The place is probably acceptable if you can touch the body without burning your hand. If necessary, a flexible armor style device may be recommended to remove the enclosure from the heat source.
Drilling Mounting Hole
For best results, follow the outlines provided in the drill kit manual. Other points to pay particular attention to:
Mounting Hole Concentricity
Transducer tips should be mounted in the center of the hole (within 0.002 "). If the transducer tip is not centered, it may become deformed during insertion or removal. This may cause performance errors or even complete tip failure.
II. Fitting the tip
The converter tips should be mounted within 0.08 "to 0.1" of the inside of the extruder chamber. Any further, can create a cavity where the polymers can collect the pressure reading, harden it and ultimately interfere with it.
Some materials (such as nylons and polycarbonates) will actually shrink and pull the diaphragm into the extruder. This sometimes causes the diaphragm to rupture. These materials should be buried down to approximately 0.05 ".
D. Sensor Installation
• Use a high temperature anti-seize compound to facilitate transducer removal
• Mounting torque: 100-200inch / lbs. (max.500 inch / lbs.)
• The polymer must be in a molten state when the converter is inserted
E. Electrical Connection
• From motors, heaters etc. Care must be taken to prevent electrical interference.
Grounding: Be sure to ground the cable above the converter, but NOT at the device side
Twisted pair cables reduce problems caused by induced currents
Perform Zero and Gap Calibration
Follow the device instructions.
You can contact MPS Melt Pressure Sensor for detailed information.