About Melt Pressure Sensors / Transmitters

1 Working Principle

   The working principle of a melt pressure sensor is that the pressure of the medium acts directly on the sensor diaphragm, causing a micro-displacement proportional to the medium pressure. This displacement causes a change in the sensor's resistance, which is detected by electronic circuitry and converted into a standard signal corresponding to the pressure.

2 Sensor Installation

   The diaphragm of the sensor is the most vulnerable part. Do not remove the protective cap before installation. During installation, take care to protect the diaphragm of the sensor. The installation hole must be machined in accordance with the technical requirements of the installation hole dimension diagram and dimension table to avoid damage to the diaphragm caused by non-standard installation holes, which could affect the normal operation of the sensor.

3 Sensor Removal

   The pressure transmitter must be removed under heated conditions (plastic melting point). When removing the transmitter, ensure that the diaphragm does not come into contact with pressure. The force applied to remove the transmitter must only be applied to the shaft (hexagonal), and no force should be applied to the transmitter head.

4 Sensor Cleaning

   To clean the diaphragm, the transmitter's sealing surface and threads must be heated to the same temperature as the plastic melting point. The diaphragm and sealing surface can be wiped clean with a soft cloth. The threads and rigid rod can be cleaned with a steel brush or copper brush (do not allow the steel brush to come into contact with the diaphragm surface). After cleaning, immediately screw the protective cap onto the threads at the front end of the rigid rod to prevent damage to the front measurement head.

5 Hazardous Areas

In the installation sealing area of the melt pressure transmitter, there is a risk of medium leakage if the pressure transmitter is not installed or removed correctly.

6 Most Common Faults and Inspection Methods

1. Zero Point Drift

By performing a zero calibration on the sensor, the sensor output value can be reset to zero, eliminating the effects of zero point drift and ensuring the accuracy and stability of the sensor output value. The zero calibration process must be performed under no pressure.

2. Plastic Melt Leakage Issue

At high temperatures, perform a secondary tightening to ensure full contact between the sealing surfaces.

3. Unstable Output Signal of the Pressure Sensor

This issue is typically caused by inadequate grounding of the equipment. Inspect the equipment wiring.

4. Large Pressure Deviation

Use the 80% calibration function. If calibration shows deviation, the sensor must be recalibrated.

Product Series Classification

1 GM Series High Temperature Melt Pressure Sensor/Transmitter

   The GM series of high-temperature melt pressure sensors feature a stainless steel body, with other components manufactured using special processes and subjected to rigorous high-strength testing. The diaphragm is protected by a special titanium compound coating, making it resistant to substances with high viscosity and friction. This series offers a long service life, precise measurement performance, and reduced temperature drift for enhanced stability. Thanks to the use of NTX eco-friendly alloy medium filling technology, these sensors are suitable for applications in the food and pharmaceutical industries.

2 CM Series High Temperature Melt Pressure Sensor/Transmitter

   The CM series of high-temperature melt pressure sensors feature a stainless steel body, with other components manufactured using special processes and subjected to rigorous high-strength testing. The diaphragm is protected by a special titanium compound coating, making it resistant to substances with high viscosity and friction. This series offers a long service life, precise measurement performance, and reduced temperature drift for enhanced stability. Thanks to the use of NTX eco-friendly alloy medium filling technology, these sensors are suitable for applications in the food and pharmaceutical industries.

3 CMC Series High Temperature Melt Pressure Sensor/Transmitter

±0.25% FSO and ±0.5% FSO accuracy options available, 80% internal calibration, excellent stability and repeatability. The CMC series of melt pressure sensors and transmitters offer multiple output signals, including 3.33 mV/V, 0-5 V, 0-10 V, and 4-20 mA, with various electrical connection options. Featuring a special threaded installation design, they offer simplicity, reliability, long service life, precise measurement performance, and reduced temperature drift for enhanced stability. The unique exposed design meets the demands of special application environments.

4 GMR Series High Temperature Melt Pressure Transmitter

   The GMR series high-temperature melt pressure transmitter uses TI series high-performance digital chips. The circuit design complies with SIL2, PL'C' safety performance standards. It controls the range limit through relay output to ensure the safety of extrusion equipment and production lines, effectively reducing damage to equipment caused by pressure overload and unpredictable personal safety accidents. It is suitable for extrusion equipment and production lines requiring precision process control, and is applied in fields such as refrigeration, chemical engineering, and environmental protection.

5 GMX Series High Temperature Melt Pressure Transmitter

   The GMX series products are intelligent 4…20mA+Hart protocol melt pressure transmitters designed for use in explosive hazardous locations. They feature a fully stainless steel welded structure and offer a choice of threaded or flanged mounting options. High-performance core components ensure high stability and measurement accuracy, and with proper handling, they will have a longer service life.

6 GMPGX Explosion-Proof Series High-Temperature Melt Pressure Transmitter

   The GMPGX series of high-temperature melt pressure transmitters feature a stainless steel body, with other components manufactured using special processes and subjected to rigorous high-strength testing. The diaphragm is protected by a special coating made from a titanium compound, ensuring it remains unaffected by substances with high viscosity and friction. This series of products features a long service life, precise measurement performance, food-grade transmission medium, and reduced temperature drift for greater stability. Thanks to the use of NTX eco-friendly alloy medium filling technology, this series of products is suitable for use in the food and pharmaceutical industries.

7 GMPG Series Melt Mechanical Pressure Gauge

   The GMPG series of melt mechanical pressure gauges are specialized products used to measure pressure in the injection molding industry and high-temperature environments in the chemical fiber industry. With a special coated diaphragm and highly wear-resistant coating, they can operate normally at high temperatures of up to 400°C. They are installed using standard threaded connections and feature high stability and a long service life.

9 GMP New Series Melt Pressure Sensors

   The GHP series melt pressure sensors (transmitters) are specifically designed for monitoring the pressure of liquids, gases, or viscous substances at high temperatures. These substances must be in a liquid, gaseous, or viscous flow state, with normal operating pressure not exceeding the upper limit of the measurement range and instantaneous pressure not exceeding 150% of the upper limit of the measurement range (based on the diaphragm surface). The products feature high-performance core components and a robust analog circuit design with enhanced interference resistance. They are calibrated for linearity at 300°C, ensuring high measurement accuracy. Proper handling is essential to maximize their service life.

10 GMP High Precision Series Melt Pressure Sensors

   The GHP series melt pressure sensors (transmitters) are specifically designed for monitoring the pressure of liquids, gases, or viscous substances at high temperatures. These substances must be in a liquid, gaseous, or viscous flow state, with normal operating pressure not exceeding the upper limit of the measurement range and instantaneous pressure not exceeding 150% of the upper limit of the measurement range (based on the diaphragm surface). Featuring high-performance core components and an analog circuit design with enhanced interference resistance, these sensors are calibrated for linearity at 200°C, ensuring high measurement accuracy. Proper handling is essential to maximize their service life.

Application areas

   Melt pressure sensors are primarily used for pressure measurement and control of molten materials under high-temperature conditions. These sensors are widely applied in equipment such as chemical fiber plastics, spinning, and polyvinyl acetate rubber machinery for pressure measurement and control of high-temperature fluid media.

Application of Melt Pressure Sensors in Extrusion Production Lines

   By installing melt pressure sensors and pressure control devices at the mold inlet connection, automated production can be achieved, resulting in more stable production rates and reduced material waste. These sensors also play a crucial role in enhancing production safety, protecting production equipment, and extending their service life.

We offer customers a variety of melt pressure sensors suitable for different applications with maximum temperatures up to 540°C. Our products feature a wide measurement range and high precision.

Contact us

Phone: 400 616 0338

Email: info@graeff.net

Website: www.graeff.net