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Melt Pressure Transmitter: A Core Sensor for Precise Data Measurement in High-Temperature Processes
In high-temperature and high-pressure processes such as plastic extrusion, rubber vulcanization, metal die casting, and chemical reactions, pressure data is not only a direct reflection of equipment operating conditions but also a key basis for process stability, product consistency, and production safety.
The melt pressure transmitter is a critical measurement device specifically designed for such extreme operating conditions.
Nexisense melt pressure transmitters are designed with high accuracy, high reliability, and long-term stability as core objectives, providing solid data support for industrial sites that require accurate and real-time pressure data.
What Is a Melt Pressure Transmitter
A melt pressure transmitter is a specialized pressure sensor used to measure the pressure of liquids or semi-fluid media in a high-temperature molten state. Unlike conventional pressure transmitters, its core design must simultaneously handle:
High-temperature environments (typically 300–400 °C or even higher)
High-pressure conditions (tens of MPa)
Viscous, high-viscosity, coke-prone, or corrosive media
Continuous operation and dynamic pressure fluctuations
Therefore, melt pressure transmitters feature distinct industrial-specific designs in structure, materials, and signal processing.
Working Principle and Measurement Mechanism
Nexisense melt pressure transmitters typically use strain-gauge or thin-film pressure sensing principles.
When the molten medium pressure acts on the sensor’s front diaphragm, the diaphragm undergoes slight elastic deformation. This deformation is converted into an electrical signal through:
Metal strain gauge bridge circuits
High-temperature thin-film strain technology
Supporting high-temperature compensation and signal amplification circuits
The internal circuitry performs temperature compensation, linear calibration, and filtering, ultimately outputting stable industrial standard signals (such as 4–20 mA) for real-time acquisition by PLCs, DCS, or control systems.
Throughout the measurement process, the sensor must maintain mechanical stability and electrical consistency to ensure long-term drift-free measurement.
Core Application Scenarios of Melt Pressure Transmitters
Plastic Extrusion and Injection Molding Processes
In plastic extrusion production lines, melt pressure directly determines:
Extrusion flow stability
Dimensional accuracy of products
Surface quality and internal structural consistency
Melt pressure transmitters can monitor pressure changes inside the screw barrel in real time, enabling closed-loop control to adjust screw speed or heating power, preventing dimensional deviations and surface defects caused by melt fluctuations.
Typical operating conditions include high temperatures, high viscosity, and corrosive challenges from materials such as PVC and PET.
Rubber Vulcanization and Compounding Production Lines
During internal mixing and vulcanization processes, pressure stability directly affects rubber mixing uniformity and final performance.
Melt pressure transmitters can accurately capture transient pressure changes during mixing, providing a basis for process parameter adjustment.
Given the strong adhesion characteristics of rubber, sensors typically use ceramic or specially coated diaphragms to reduce the impact of media adhesion on measurement.
Metal Die Casting and Forming Industry
During high-pressure injection and holding stages, pressure curves are critical indicators for assessing complete filling and overflow risks.
Melt pressure transmitters can record complete pressure change processes for:
Mold commissioning and process optimization
Pressure anomaly early warning
Die casting quality traceability and analysis
Such applications place higher demands on sensor impact resistance and response speed.
Chemical Reactors and High-Risk Process Monitoring
In the chemical industry, molten or high-temperature reaction media are often associated with flammable and explosive risks.
Nexisense melt pressure transmitters can provide explosion-proof or intrinsically safe designs as required, meeting the needs of hazardous areas. Meanwhile, internal digital filtering and signal stabilization technologies effectively suppress interference from bubbles and pulsation, ensuring reliable readings.
Installation and Commissioning Key Points
Installation Orientation Selection
Vertical installation is preferred, as it facilitates exhaust and stable pressure transmission.
If lateral installation is required due to space constraints, ensure that the angle between the medium flow direction and the sensor axis remains within a reasonable range to avoid measurement errors.
Insulation and Heat Tracing Configuration
For media prone to solidification, appropriate heat tracing devices should be configured along with independent temperature control systems to prevent medium cooling blockage or sensor overheating and aging.
Calibration and Verification Procedures
In addition to factory calibration, dynamic verification under actual operating conditions is recommended to ensure measurement accuracy under real media and temperature conditions.
Vibration Resistance and Mechanical Protection
On high-vibration equipment, vibration-damping gaskets or flexible connectors can be used to reduce mechanical stress on the sensor and improve long-term stability.
Technical Specifications
| Parameter | Value |
|---|---|
| Measuring Range | 0–5 MPa to 200 MPa |
| Overload Pressure | 150% FS |
| Overall Accuracy | ±1.0% FS (including linearity, repeatability, and hysteresis) |
| Output | 4–20 mA, 0–10 V, 0–5 V |
| Supply Voltage | 24 VDC (12–36 V) |
| Output Impedance | 350 Ohms ±10% |
| Internal Self-Calibration | 80% FS ±1% |
| Insulation Resistance | 200 MΩ @ 100 Vdc |
| Diaphragm Temperature | 400 °C |
| Diaphragm Material | 15-5PH coated stainless steel |
| Electrical Connection | 1/2 NPT explosion-proof cable gland |
| Process Connection | 1/2"-20UNF, M14×1.5, M18×1.5, M22×1.5, G3/4 |
| Torque | Maximum 500 inch/lbs |
Frequently Asked Questions (FAQ)
Can melt pressure transmitters operate long-term at high temperatures?
Yes. Their structure and materials are specifically designed for continuous high-temperature operation, provided that installation and heat dissipation conditions are appropriate.
Can they directly replace conventional pressure transmitters?
No. Conventional pressure transmitters are prone to failure under high-temperature molten conditions. Melt pressure transmitters are specialized devices.
How can service life be extended?
Proper selection, correct installation, appropriate heat tracing, and regular calibration are key to extending service life.
Conclusion
Melt pressure transmitters are indispensable core sensors in high-temperature and high-pressure industrial processes.
Through stable and reliable structural design, precise measurement performance, and good system compatibility, Nexisense melt pressure transmitters provide trustworthy pressure data support for the plastics, rubber, metal, and chemical industries.
In today’s pursuit of product consistency, process stability, and production safety, accurate melt pressure measurement is no longer an optional add-on but a fundamental requirement for modern industrial precision control.
