HM Series — Explosion-Proof Pressure Measurement

HM60 Explosion-Proof Pressure Transmitter

Q: What hazardous area zones is the HM60 rated for?

The HM60-E (Ex ia ⅡCT5) is rated for Zone 0, Zone 1, and Zone 2 when used with appropriate safety barriers. The HM60-D (Ex d ⅡCT6) is suitable for Zone 1 and Zone 2. The combined HM60-ED meets Zone 1 and Zone 2 requirements. All models carry T5 or T6 temperature class ratings, meaning the maximum surface temperature does not exceed 100°C (T5) or 85°C (T6) — suitable for most gas groups including IIC (hydrogen, acetylene).

Q: Can the HM60 measure differential pressure?

Yes. The HM60 supports gauge, absolute, and differential pressure measurement. When ordering, select pressure type code "D" for differential pressure. This is useful for flow measurement across orifice plates, filter monitoring, and level measurement in sealed tanks. For dedicated differential pressure applications requiring higher static pressure ratings, consider our HM31 or HM3051 differential pressure transmitters.

Q: What display and output options are available?

The HM60 offers four output signals: 4–20 mA (A1) for standard industrial loops, 1–5 V DC (V1) and 0–5 V DC (V2) for data acquisition systems, and 0.5–4.5 V DC (V3) for embedded applications. Optional local displays include a pointer gauge (L1, 0–100%), 3½-digit LCD (L2) for general use, and 3½-digit LED (L3) for low-light environments. For most industrial process control, we recommend 4–20 mA output with an LCD display for local verification.

CNEx-certified explosion-proof pressure transmitter with dual protection modes — intrinsically safe (Ex ia ⅡCT5) and flameproof (Ex d ⅡCT6). Built on German HMK polysilicon thin-film sensing technology, the HM60 delivers ±0.1% FS accuracy across a -100 kPa to 200 MPa range for hazardous Zone 1/2 environments in oil & gas, mining, and chemical processing.

✦ 200 MPa Max Range ✦ ±0.1% Accuracy ✦ Ex ia/Ex d Certified ✦ ≤1 ms Response

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HM60 Explosion-Proof Pressure Transmitter with Ex ia and Ex d certification

Overview

The HM60 Explosion-Proof Pressure Transmitter is purpose-built for hazardous environments where flammable gases, vapors, or combustible dusts may be present. Holding CNEx-issued certificates for both intrinsic safety (Ex ia ⅡCT5, cert. CNEx07.0988) and flameproof enclosure (Ex d ⅡCT6, cert. CNEx08.2405), the HM60 meets the stringent requirements of Zone 1 and Zone 2 hazardous areas — making it the go-to solution for oil fields, mining operations, chemical plants, and natural gas facilities.

At its core, the HM60 employs a German HMK polysilicon thin-film sensing element, welded directly to the 316 stainless steel pressure port in a monolithic construction. This eliminates fill fluid and internal O-ring seals at the sensing interface, resulting in exceptional long-term stability (±0.1% FS/year typical) and resistance to vibration and shock. The transmitter covers a remarkably wide measurement span from vacuum (-100 kPa) through low pressure (200 Pa) up to 200 MPa, with gauge, absolute, and differential pressure modes available.

Three accuracy classes — ±0.1% FS, ±0.25% FS, and ±0.4% FS — allow engineers to balance precision against cost for each application. The integrated signal conditioning circuit outputs standard 4–20 mA or voltage signals, powered by a 12–36 VDC supply. A response time of ≤1 ms ensures the HM60 captures fast pressure transients, critical for safety monitoring in explosive atmospheres. Built-in reverse polarity and overvoltage protection further enhance field reliability.

The HM60 is available in three explosion-proof variants: the HM60-E (intrinsically safe, requires safety barrier), the HM60-D (flameproof enclosure), and the HM60-ED (combined intrinsic safety + flameproof, no barrier required). Optional LCD/LED displays and flush-diaphragm configurations add further versatility. Compared to traditional explosion-proof transmitters, the HM60 offers a significantly smaller form factor, lower weight (~0.5 kg), and competitive pricing without compromising on precision sensing performance.

Technical Specifications

Parameter	Specification
Measuring Range	-100 kPa ~ 0 ~ 200 Pa … 5 kPa … 200 MPa
Pressure Type	Gauge / Absolute / Differential
Measuring Medium	Gases or liquids compatible with 316 stainless steel
Overall Accuracy	±0.1% FS / ±0.25% FS / ±0.4% FS (selectable)
Long-Term Stability	Typical: ±0.1% FS/year; Max: ±0.2% FS/year
Zero Temp. Drift	Typical: ±0.02% FS/°C; Max: ±0.05% FS/°C
Span Temp. Drift	Typical: ±0.02% FS/°C; Max: ±0.05% FS/°C
Overload Capacity	200% FS (100 MPa models: 110% FS)
Response Time	≤1 ms
Resolution	Infinite (theoretical); 1/100,000 (typical)
Output Signal	4–20 mA / 1–5 V DC / 0�35 V DC / 0.5–4.5 V DC
Power Supply	12–36 VDC (typically 24 VDC)
Load Resistance	≤ (U-12) / 0.02 Ω
Operating Temperature	-20 ~ 85°C
Compensated Temperature	-20 ~ 60°C
Insulation Resistance	≥ 2000 MΩ at 100 VDC
Vibration Resistance	< 0.1% FS at 20 Hz – 1000 Hz
Wetted Material	316 stainless steel
Process Connection	M20×1.5, G1/4, custom available
Electrical Connection	Cable type (IP67) / Hirschmann DIN 43650A (IP65)
Protection Grade	IP65 (connector) / IP67 (cable) per IEC 60529
Explosion-Proof (IS)	Ex ia ⅡCT5 (CNEx07.0988)
Explosion-Proof (FP)	Ex d ⅡCT6 (CNEx08.2405)
Weight	Approx. 0.5 kg
Optional Display	Pointer (0–100%) / 3½ LCD / 3½ LED
Certifications	CNEx, CE, RoHS

Key Features

Dual Explosion-Proof Certification — Ex ia + Ex d

Holds CNEx certificates for both intrinsic safety (Ex ia ⅡCT5) and flameproof enclosure (Ex d ⅡCT6). The combined HM60-ED variant eliminates the need for an external safety barrier, simplifying installation in Zone 1/2 hazardous areas while maintaining full compliance.

±0.1% FS Accuracy — Three Selectable Classes

Choose from ±0.1%, ±0.25%, or ±0.4% FS accuracy to match your application requirements. Combined with ±0.02% FS/°C temperature drift and ±0.1% FS/year long-term stability, the HM60 maintains measurement integrity across demanding field conditions.

German HMK Polysilicon Thin-Film Sensor

The sensing element is a German HMK polysilicon thin-film chip welded directly to the 316 SS pressure port. This monolithic construction eliminates internal fill fluid and O-rings at the sensing interface, delivering superior vibration resistance and a lifecycle exceeding 10⁸ pressure cycles.

≤1 ms Response Time — Ultra-Fast Detection

A response time of 1 ms or less enables rapid detection of pressure surges and transients — critical for safety shutdown systems in explosive atmospheres. The vibration immunity (<0.1% FS across 20–1000 Hz) ensures stable readings even on pumps and compressors.

200 MPa Range — Vacuum to Ultra-High Pressure

Covering -100 kPa vacuum through low-pressure ranges (200 Pa) up to 200 MPa, the HM60 handles everything from gas pipeline monitoring to hydraulic system testing. Gauge, absolute, and differential pressure modes are all available within a single product family.

Built-In Protection — Reverse Polarity & Overvoltage

Integrated reverse-polarity and overvoltage protection circuits prevent damage from incorrect wiring — a common concern during field installation in remote hazardous locations. Optional LCD/LED displays enable local readout without additional instrumentation.

Applications

Oil & Gas — Wellhead & Pipeline Monitoring

Monitor wellhead pressure, pipeline flow, and separator vessel levels in Zone 1/2 classified areas. The HM60-ED combined protection eliminates the need for safety barriers, reducing installation cost and complexity in remote oilfield locations.

Mining — Underground Ventilation & Hydraulics

Measure air pressure in mine ventilation systems and hydraulic pressure in longwall mining equipment. The intrinsic safety certification meets coal mine methane-atmosphere requirements, while ≤1 ms response time detects sudden pressure changes critical for miner safety.

Chemical Processing — Reactor & Vessel Pressure

Control reactor pressure and storage tank levels where flammable solvents and vapors create explosive atmospheres. The flameproof (Ex d) housing contains any internal ignition, while ±0.1% FS accuracy supports precise process control of exothermic reactions.

Natural Gas — Transmission & Distribution

Monitor pressure in compressor stations, metering skids, and city gate regulator stations. The wide 200 MPa range covers high-pressure transmission lines, while the differential pressure option enables flow metering across orifice plates in gas custody transfer.

Power Generation — Boiler & Turbine Systems

Measure steam pressure in boiler drums, turbine inlet lines, and fuel gas systems. The explosion-proof rating is required for hydrogen-cooled generators and coal dust environments. Excellent long-term stability reduces calibration frequency in continuous-operation power plants.

Pharmaceutical — Solvent & Clean Room Systems

Pharmaceutical manufacturing involves flammable solvents (ethanol, isopropanol, acetone) requiring explosion-proof instrumentation. The optional flush-diaphragm (P) option provides crevice-free measurement suitable for CIP/SIP cleaning cycles in GMP-regulated facilities.

Outline Dimensions

HM60-E Intrinsically Safe — Cable & Connector Type

HM60-E Intrinsically Safe Pressure Transmitter dimensions drawing — cable and connector type

HM60-D / HM60-ED Flameproof — With Housing

HM60-D HM60-ED Explosion-Proof Pressure Transmitter with flameproof housing dimensions drawing

Ordering Guide

Use the model code table below to configure your HM60 order. Example: HM60 (0~1.6 MPa) — 1 — A1 — F1 — W3 — D = HM60 Explosion-Proof Pressure Transmitter, 0–1.6 MPa range, ±0.4% FS accuracy, 4–20 mA output, M20×1.5 connection, flameproof style enclosure, Ex d ⅡCT6.

Code Position	Code	Description
Pressure Type	G	Gauge pressure (default, may be omitted)
	A	Absolute pressure
	D	Differential pressure
Range	Specify measuring range: 0 ~ X kPa or MPa
Accuracy	1	±0.4% FS
	2	±0.25% FS
	3	±0.1% FS
Output Signal	A1	4–20 mA
	V1	1–5 V DC
	V2	0–5 V DC
	V3	0.5–4.5 V DC
Process Connection	F1	M20×1.5 external thread
	F2	G1/4 external thread
	F0	Special (specify in order)
Enclosure / Cable	W1	Cable type, IP67, 2 m (IS models only)
	W2	Hirschmann DIN 43650A, IP65 (IS models only)
	W3	Explosion-proof enclosure — Style A
	W4	Explosion-proof enclosure — Style B
	W0	Special (specify in order)
Display (optional)	L1	Pointer gauge (0–100%)
	L2	3½-digit LCD display
	L3	3½-digit LED display
Special Options	P	Flush diaphragm
	E	Intrinsically safe — Ex ia ⅡCT5 (requires safety barrier)
	D	Flameproof — Ex d ⅡCT6

Note: W1/W2 cable/connector options are limited to HM60-E intrinsically safe models. For HM60-D and HM60-ED models, use W3/W4 explosion-proof enclosure styles with M20×1.5 or G1/2 threaded conduit entries.

HM50 Anti-Corrosive Pressure Transmitter

HM50 Anti-Corrosive Transmitter

Chemical-resistant materials for corrosive media. PTFE-lined diaphragm with all-welded construction.

HM70 Sanitary Flat Membrane Pressure Transmitter

HM70 Sanitary Flat Membrane Transmitter

Flush diaphragm design for hygienic applications. FDA compliant, CIP/SIP compatible.

HM80 High-Temperature Pressure Transmitter

HM80 High-Temperature Transmitter

Operates up to 350°C with cooling structure. Designed for steam, thermal oil and high-temp processes.

HM20 General Purpose Pressure Transmitter

HM20 General Purpose Transmitter

Versatile 4-20mA pressure transmitter for general industrial applications. Wide range coverage with robust design.

Frequently Asked Questions

The HM60-E is an intrinsically safe (Ex ia ⅡCT5) transmitter that limits electrical energy below ignition levels — it requires an external safety barrier between the transmitter and the control system. The HM60-D uses a flameproof enclosure (Ex d ⅡCT6) that contains any internal explosion, preventing propagation to the surrounding atmosphere — no safety barrier is needed, but conduit entries must be sealed. The HM60-ED combines both protections (Ex ia + Ex d), providing the highest safety level without requiring a safety barrier, making it the simplest to install in Zone 1/2 areas.

It depends on the model variant. The HM60-E (intrinsically safe only) requires a safety barrier or galvanic isolator between the transmitter and the non-hazardous area power supply/controller. The HM60-D (flameproof only) does not require a safety barrier — the flameproof enclosure itself provides protection. The HM60-ED (combined) also does not require a safety barrier, as the flameproof housing provides the external protection layer. For simplicity of installation, we recommend the HM60-ED for most applications.

The HM60-E (Ex ia ⅡCT5) is rated for Zone 0, Zone 1, and Zone 2 when used with appropriate safety barriers. The HM60-D (Ex d ⅡCT6) is suitable for Zone 1 and Zone 2. The combined HM60-ED meets Zone 1 and Zone 2 requirements. All models carry T5 or T6 temperature class ratings, meaning the maximum surface temperature does not exceed 100°C (T5) or 85°C (T6) — suitable for most gas groups including IIC (hydrogen, acetylene).

The HM60 differentiates itself through its German HMK polysilicon thin-film sensor (welded, no fill fluid), dual Ex ia + Ex d certification in a single product family, three selectable accuracy classes (down to ±0.1% FS), and compact form factor (~0.5 kg vs. 2–3 kg for traditional explosion-proof transmitters). The built-in reverse polarity and overvoltage protection adds field reliability that many competitors require external barriers to achieve. Its price-to-performance ratio is particularly competitive against European-brand explosion-proof transmitters.

Yes. The HM60 supports gauge, absolute, and differential pressure measurement. When ordering, select pressure type code “D” for differential pressure. This is useful for flow measurement across orifice plates, filter monitoring, and level measurement in sealed tanks. For dedicated differential pressure applications requiring higher static pressure ratings, consider our HM31 or HM3051 differential pressure transmitters.

The HM60 offers four output signals: 4–20 mA (A1) for standard industrial loops, 1–5 V DC (V1) and 0–5 V DC (V2) for data acquisition systems, and 0.5–4.5 V DC (V3) for embedded applications. Optional local displays include a pointer gauge (L1, 0–100%), 3½-digit LCD (L2) for general use, and 3½-digit LED (L3) for low-light environments. For most industrial process control, we recommend 4–20 mA output with an LCD display for local verification.

Need an Explosion-Proof Pressure Solution?

Tell us your hazardous area classification, pressure range, and process conditions — our engineers will recommend the optimal HM60 configuration (Ex ia, Ex d, or combined Ex ia+Ex d) and provide a competitive quotation. Our engineers typically respond within 12 business hours.