Strain gauge pressure transmitter HMJ

HARTbuilt-in transmitterflange-mount

Overview
HMJ series Melt pressure transmitters are HART-enabled pressure transmitters designed for high-temperature melt applications and for use in potentially explosive atmospheres. They measure process/media pressure via hydraulic transmission and are rated for media temperatures up to 400 °C.

Construction and measurement principle
The sensor uses hydraulic transmission (incompressible fill fluid) to transfer process pressure to the sensing element. Strain gauge technology converts mechanical stress into an electrical signal compatible with HART communication.

Main features

• Digital output: HART protocol
• Protection type: Ex d (flameproof)
• Certifications available: IECEx, ATEX, NEPSIEx
• Media temperature capability up to 400 °C (Melt applications)

Explosion protection & environmental ratings

• Group II, category 2G, 2D (EPL Gb/Db)
• Gas protection: Ex db IIC T6 / T5 Gb
• Dust protection: Ex tb IIIC T85°C / T100°C Db
• Ambient temperature: -20 °C to +60 °C (T6) and -20 °C to +85 °C (T5)

Typical mechanical features

• Pressure ranges: from 0–17 bar to 0–1000 bar (approx. 0–250 to 15000 psi)
• Standard process connections: 1/2-20 UNF, M18 x 1.5, mounting flange Ø66.3 mm
• Diaphragm materials: 15-5 PH stainless steel with GTP+ coating; for ranges <100 bar: 17-7 PH corrugated diaphragm with GTP+
• Other diaphragm types and process connections available on request

Accuracy & approvals

• Accuracy classes: < ±0.25% FS (H) and < ±0.5% FS (M)
• Approvals: IECEx, ATEX, NEPSIEx; FM approval indicated for specific versions

Working principle / additional technical notes

• Hydraulic transmission transfers process pressure via an incompressible fluid to the sensing diaphragm
• Strain gauge measuring element converts pressure-induced stress to an electrical signal for HART digital output and standard analog interfaces

Technical specifications

• Model name: HMJ
• Communication protocol: HART
• Measurement principle: Strain gauge with hydraulic transmission
• Pressure ranges: 0–17 to 0–1000 bar (approx. 0–250 to 15000 psi)
• Accuracy: < ±0.25% FS (H); < ±0.5% FS (M)
• Diaphragm: 15-5 PH stainless steel (GTP+); 17-7 PH corrugated for <100 bar
• Media temperature capability: up to 400 °C
• Protection type: Ex d (flameproof)
• Certifications: IECEx, ATEX, NEPSIEx (FM listed for specific models)
• Standard threads/mounting: 1/2-20 UNF, M18x1.5, flange Ø66.3 mm