Main features & Overview


The HMX4 series of Gefran, are pressure transmitters for using in High temperature environment and specifically designed for melt pressure measurement and available only to be used in large-scale fixed installations or in large-scale stationary industrial tools, typically extruders, or for laboratory B2B equipment for R&D purposes according to the European Directive 2011/65/EU (see informative note RoHS II).

The HMX4 series of Gefran are flanged pressure transmitters with HART communication protocol for using in high temperature environment with explosive atmosphere presence.

The main characteristic of this series is the capability to read temperature of the media up to 400°C.

The constructive principle is based on the hydraulic trasmission of the pressure.

The fluid-filled system assures the temperature stability.

The physical measure is transformed in a electrical measure by means of strain-gauge technology.

The SIL2 and PL d approvals make the product suitable for use in the Functional Safety applications, particularly in the process plants for the production of polymers, where

it is an essential requirement.


• Pressure ranges from: 0-17 to 0-2000 bar/0-250 to 0-30000 psi

• Thick film extensimetric measurement principle

• Accuracy: < ±0.25% FS (H); < ±0.5% FS (M)

• SIL2 and PL d approvals for Functional Safety

• ATEX certification for potentially explosive atmospheres

• Flanged version

• Protection level: IP66 (6-pin connector)

• 1/2-20UNF, M18x1.5 standard threads; other types available on request

• Standard diaphragm is 15-5 PH stainless steel with GTP+ coating

• 17-7 PH corrugated stainless steel diaphragm with GTP+ coating for ranges below 100 bar-1500 psi

• Other diaphragm types available on request


Gefran product range brochure
Melt pressure sensors
4.0 Gefran product catalog
4.0 plastic application catalogue
Flyer Melt for Polymers
HMX4 Datasheet
HWX4 - HMX4 Safety note
Product user manual
H pressure transmitter description file
H pressure transmitter description files for HH475


Hart Certifications - Certificate of Registration HCF Verified
GTP+ FDA Certificate
HM_HW_HK Melt HART Certification
EU Conformity declaration_HMX FS min 500bar SIL 2