Installation Specifications for Melt Pressure Transmitters

— The Key to Achieving Accurate and Reliable Measurement Under High-Temperature and High-Pressure Conditions

In processes such as plastic extrusion, rubber mixing, chemical reactions, and high-temperature fluid transportation, melt pressure not only reflects the operating status of equipment but also directly affects product quality, consistency, and production safety.

Compared with conventional pressure measurement devices, melt pressure transmitters operate for long periods in environments characterized by high temperature, high pressure, high viscosity, and even strong corrosiveness. The standardization of their installation often determines whether the measurement system can operate stably over the long term.

Nexisense melt pressure transmitters are designed with full consideration of harsh industrial conditions. However, their performance advantages can only be fully realized through correct installation and proper maintenance.

Product Features of Melt Pressure Transmitters

Nexisense melt pressure transmitters are engineered to meet the demands of reliable measurement in high-temperature conditions and offer the following core features:

• Measurement accuracy better than ±0.5% FS, meeting the requirements of precise process control

• Adjustable zero and full scale for convenient on-site calibration and system matching

• Excellent long-term stability and repeatability, suitable for continuous operation

• Diaphragm made of 17-4PH coated stainless steel, combining high-temperature resistance, corrosion resistance, and mechanical strength

• Structural and interface designs compatible with mainstream equipment, enabling replacement of similar imported products in most applications

These features provide a solid foundation for high-temperature melt pressure measurement, but true reliability depends on standardized installation and systematic management.

Key Preparations Before Installation

Verification of Model Selection and Operating Conditions

Before installation, the following parameters must be carefully verified:

• The pressure range must cover the maximum operating pressure of the system with an adequate safety margin

• The operating temperature range must meet the maximum process temperature of the melt

• The viscosity and corrosiveness of the medium must match the materials of the wetted parts

• The process connection type must be compatible with the pipeline or equipment interface and sealing surface design

Proper selection is the prerequisite for avoiding drift, diaphragm damage, and premature failure.

Verification of Material Compatibility

Different melt media impose significantly different requirements on diaphragm materials, and selection should be based on medium composition:

• Fluoropolymer applications: priority to Hastelloy C-276 lined structures

• Strongly acidic or corrosive environments: PTFE diaphragm structures are recommended

• High-abrasion and high-shear conditions: tungsten carbide coatings or high-strength alloy diaphragms are preferred

Improper material selection is often the root cause of diaphragm perforation and measurement failure.

Accessory and System Integrity Inspection

For high-viscosity or easily solidifying media, ensure the following accessories are complete:

• Flushing rings or cleaning ports

• Cooling or thermal isolation sleeves

• Filters or protective components

• Heat tracing systems and temperature control devices

These accessories are not optional but essential for long-term stable operation.

Installation Orientation and Alignment Requirements

Correct Installation Orientation

During installation, ensure that:

• The sensor axis is aligned with the direction of medium flow

• The deviation angle is controlled within ±5°

• For side-wall installations, the pressure port is adjusted so the melt directly impacts the center of the diaphragm

Under high-pressure conditions, the impulse line should be inclined toward the transmitter body by 3°–5°, and an exhaust valve should be installed at the highest point to prevent trapped gas from affecting measurements.

Concentricity and Mechanical Alignment Control

The pressure tapping port and transmitter flange must maintain good concentricity:

• Parallelism error should be controlled within 0.1 mm/m

• Excessive misalignment can introduce shear stress, leading to deformation or rupture of the sensing element

For high-precision or high-pressure applications, laser alignment tools are recommended for installation verification.

Sealing Structure and Environmental Protection Specifications

Multi-Layer Sealing System

Reliable sealing is the safety baseline of melt pressure measurement:

• Primary sealing: use spiral-wound metal graphite gaskets and tighten strictly according to the manufacturer’s specified torque

• Secondary protection: apply sealant where necessary to prevent melt penetration into the electrical housing through micro-gaps

Sealing systems should be regularly leak-tested, especially under cyclic high-temperature conditions.

Enhanced Environmental Resistance

In complex industrial environments, protective design is critical:

• Ingress protection up to IP68 can be achieved using waterproof junction boxes and M12 connectors

• Dusty environments should adopt a combination of sintered bronze filters and hydrophobic breathable membranes

• Explosion-proof models must comply with Ex d IIC T6 requirements, with grounding resistance less than 1 Ω

Electrical Safety and Signal Reliability

Grounding System Design

Melt pressure transmitters should adopt an independent and standardized grounding scheme:

• Single-point grounding with grounding resistance less than 4 Ω

• Cable shielding connected to ground at the control room end only

• Avoid multi-point grounding to prevent ground loop interference

A well-designed grounding system is fundamental to signal stability.

Cable Routing and Anti-Interference Measures

• Signal cables and power cables should be routed on separate trays with a minimum spacing of 30 cm

• When passing through strong electromagnetic interference areas, armored cables or isolation solutions are recommended

• Leave at least 20% free space inside junction boxes for maintenance and inspection

Measurement Methods, Maintenance, and Care

Measurement Method

Melt pressure transmitters typically adopt a direct-contact measurement method, where the diaphragm directly interfaces with the medium. This avoids lag and errors introduced by intermediate transmission media, making it suitable for dynamic pressure monitoring and closed-loop control.

Routine Maintenance

• Regularly check zero drift and output stability

• Clean pressure ports and remove deposits to prevent coking buildup

• Inspect heat tracing systems and temperature control devices for proper operation

Key Measures to Extend Service Life

• Strict selection according to operating conditions

• Standardized installation to avoid mechanical stress

• Proper configuration of heating and cooling systems

• Scheduled calibration and condition inspection

Frequently Asked Questions (FAQ)

Is a heat tracing system mandatory for melt pressure transmitters?
In applications involving high-viscosity or easily solidifying media, heat tracing is essential to ensure stable measurement.

Can installation orientation requirements be ignored?
No. Deviations in orientation and concentricity can significantly affect diaphragm stress and measurement accuracy.

How often should calibration be performed?
Depending on operating conditions, periodic calibration is recommended, typically every 6–12 months.

Conclusion

Melt pressure transmitters are not simple instruments that can be “installed and forgotten.” Their measurement accuracy, safety, and service life are highly dependent on standardized installation and systematic management.

Nexisense melt pressure transmitters provide a reliable foundation for high-temperature and high-pressure applications through robust structural design and material selection. Scientific installation and proper maintenance are the keys to fully unlocking their performance value.

In industrial environments that demand process stability, product consistency, and operational safety, standardized installation is not an optional enhancement but a fundamental requirement for long-term reliable operation.