HM SERIES — DIGITAL PRESSURE GAUGE

HM40 Digital Pressure Gauge

The HM40 is a high-precision digital pressure gauge co-developed with German HELM, featuring microprocessor-controlled measurement from vacuum to 100 MPa. Available with LCD or LED display, battery or mains powered, it delivers ±0.1% FS accuracy with peak value recording — ideal for laboratory calibration, equipment automation, and portable pressure measurement.

100 MPA

Max Range

±0.1% FS

Accuracy

24 Months

Battery Life

IP65

Protection

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Product Overview

The HM40 Digital Pressure Gauge is a microprocessor-controlled precision instrument co-developed by HMK TECH and German HELM. It combines a high-stability HELM piezoresistive pressure sensor with advanced low-power signal processing, delivering measurement accuracy up to ±0.1% FS across a wide range from vacuum (-100 kPa) to 100 MPa gauge pressure. The instrument is designed for engineers and metrologists who demand reliable, traceable pressure readings in both field and laboratory environments.

Unlike conventional mechanical Bourdon-tube gauges, the HM40 provides direct digital readout on either a 4-digit LCD (battery models) or high-brightness LED display (mains-powered models). Built-in peak value recording captures minimum and maximum pressures during test cycles — a feature critical for burst testing, leak detection, and process qualification. The zero-reset function, unit switching, backlight, and low-battery alarm make operation intuitive even in challenging field conditions.

The HM40 supports gauge, absolute, and differential pressure measurement with a comprehensive ordering system that lets you specify display type, dial size (80 mm or 100 mm), process connection (M20×1.5, G1/4, or custom), and mounting orientation (radial or axial). Battery-powered models achieve up to 24 months of continuous operation, making the HM40 an excellent portable reference gauge. With optional 4–20 mA or RS485 output, it also integrates into automated monitoring systems.

Engineered with German HELM sensing elements renowned for corrosion resistance, shock tolerance, and overload protection (1.5× FS), the HM40 serves as a direct replacement for analog precision pressure gauges in calibration labs, manufacturing quality control, and industrial process verification.

Technical Specifications

Parameter	Specification
Measuring Range (Gauge)	0~1 kPa … 100 MPa (selectable within range)
Measuring Range (Vacuum)	0~-1 kPa … -100 kPa (selectable within range)
Measuring Range (Absolute)	0~2 kPa … 3.5 MPa (selectable within range)
Measuring Range (Compound)	-1 kPa~1 kPa … -100 kPa~20 MPa
Pressure Type	Gauge, Absolute, Differential
Overall Accuracy	±0.1% FS / ±0.25% FS / ±0.5% FS (selectable)
Long-Term Stability	Typical ±0.2% FS; Maximum ±0.5% FS
Overload Capacity	1.5× FS (1.1× FS for 100 MPa range)
Display	4-digit LCD (battery models) / 4-digit LED (mains models)
Sampling Rate	5 Hz
Signal Output (Optional)	4–20 mA / 0–5 VDC / RS485 (custom order)
Power Supply	Battery (up to 24 months) / 24 VDC / 220 VAC / 380 VAC
Operating Temperature	-10°C to +70°C (high-temp custom available)
Wetted Material	316 stainless steel (media compatible)
Housing / Connection	304 stainless steel
Process Connection	M20×1.5 / G1/4 (standard); custom available
Dial Diameter	80 mm / 100 mm (custom available)
Protection Grade	IP65
Weight	Approx. 0.5 kg
Certifications	CE, RoHS

Key Features

±0.1% FS High Accuracy

Microprocessor-controlled measurement with selectable accuracy classes (±0.1%, ±0.25%, ±0.5% FS). German HELM sensing elements ensure long-term stability of ±0.2% FS typical — suitable for use as a reference standard gauge in calibration laboratories.

Wide Measurement Range

Covers vacuum (-100 kPa) through gauge pressure to 100 MPa, with absolute and compound pressure options. A single instrument family addresses low-pressure HVAC applications through ultra-high-pressure hydraulic testing.

24-Month Battery Life

Low-power design enables up to 24 months of continuous battery operation with LCD display. Ideal for portable field measurements, remote installations, and applications where mains power is unavailable or impractical.

Peak Value Recording

Built-in min/max recording captures pressure extremes during test cycles without external data loggers. Essential for burst testing, leak detection, and process qualification where peak values determine pass/fail criteria.

Dual Display Options

Choose between low-power 4-digit LCD for battery-operated portable use, or high-brightness 4-digit LED for permanently installed mains-powered applications. Both provide clear, real-time pressure readout with unit switching capability.

German HELM Sensing Elements

Co-developed with German HELM, the 316L stainless steel sensing element delivers exceptional corrosion resistance, shock tolerance, and 1.5× overload protection. Rated IP65 with robust stainless steel housing for demanding industrial environments.

Applications

Calibration Laboratories

With ±0.1% FS accuracy and peak value recording, the HM40 serves as a portable reference standard for verifying and calibrating pressure transmitters, switches, and gauges. Replaces analog precision gauges with traceable digital readout.

Equipment Automation

Install the HM40 with optional 4–20 mA or RS485 output to monitor pressure in automated production lines, CNC machines, and robotic systems. The IP65 housing and stainless steel construction withstand factory-floor vibration and contamination.

Pumps & Compressors

Monitor suction and discharge pressures on pumps, compressors, and hydraulic power units. The compound pressure range (-100 kPa to 20 MPa) handles both vacuum intake and high-pressure output in a single instrument.

Medical Equipment

Verify gas supply pressures in hospital gas delivery, autoclave sterilization, and medical device testing. The high-accuracy digital readout meets documentation requirements for medical quality compliance and device validation.

Energy & Heating Systems

Monitor boiler pressure, district heating pipelines, and thermal power plant auxiliaries. The 220 VAC / 380 VAC power options with LED display provide continuous, clearly visible readings in utility control rooms and substations.

Construction Machinery

Portable battery-powered operation makes the HM40 ideal for on-site hydraulic system diagnostics on excavators, cranes, and concrete pumps. The 1.5× overload rating and rugged stainless steel body survive harsh jobsite conditions.

Ordering Guide

Model Code Example: HM40 (0~100KPa) — 1 — V1 — D2 — F1

Each segment in the model code defines the pressure type, range, accuracy, power/display, dial size, and process connection. For example, the code above specifies a gauge pressure range of 0–100 kPa, ±0.5% FS accuracy, battery-powered LCD, 80 mm dial, and M20×1.5 connection.

Code	Options
Pressure Type	G = Gauge (default) \| A = Absolute \| D = Differential
Range	0~X (specify pressure value and unit, e.g. 0~100KPa, 0~10MPa)
Accuracy	0 = ±1% FS \| 1 = ±0.5% FS \| 2 = ±0.25% FS \| 3 = ±0.1% FS
Power / Display	V1 = Battery + LCD \| V2 = 24VDC + LED \| V3 = 220VAC + LED \| V4 = 380VAC + LED
Dial Size	D1 = 100 mm \| D2 = 80 mm \| D0 = Custom
Process Connection	F1 = M20×1.5 \| F2 = G1/4 \| F0 = Custom
Additional Options	J = Radial mount \| Z = Axial mount \| S = Signal output \| P = Plastic housing \| R = Corrosion-resistant

For custom configurations, specific display requirements, or volume pricing, contact our technical sales team with your application details and we will provide a tailored HM40 configuration proposal.

HM41 Electronic Pressure Switch

Need automatic switching instead of display-only measurement? The HM41 combines digital pressure display with programmable relay outputs for automated process control — ideal for pump protection and alarm triggering.

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HM200E Wireless Pressure Gauge

Want to eliminate cable wiring? The HM200E adds LoRa wireless transmission to digital pressure display, enabling cloud-based monitoring of distributed pressure points across large facilities without cable installation.

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HM22 Precision Pressure Transmitter

Need to transmit analog or digital output to a PLC/DCS? The HM22 provides ±0.075% FS accuracy with 4–20 mA, 0–10 V, or RS485 output — choose this when you need a dedicated pressure transmitter rather than a display gauge.

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Frequently Asked Questions

The HM40 is a digital pressure gauge focused on precise pressure measurement and display, with optional signal output. The HM41 is an electronic pressure switch that adds programmable relay switching outputs for process control automation — it can trigger alarms, start/stop pumps, or activate valves when pressure crosses set thresholds. Choose the HM40 when you primarily need accurate pressure reading and recording; choose the HM41 when you need automatic switching actions based on pressure levels.

Yes. The HM40 with ±0.1% FS accuracy (code “3”) is designed as a direct replacement for Class 0.1 analog precision gauges used in calibration laboratories. It eliminates parallax reading errors, provides digital documentation of measurements, and includes peak value recording that analog gauges cannot offer. Standard process connections (M20×1.5, G1/4) ensure compatibility with existing test setups.

Battery-powered models (ordering code V1) with LCD display can operate continuously for up to 24 months on a single battery set. The low-power microprocessor and LCD display minimize current draw. A built-in low-battery alarm warns you before power runs out, ensuring you never lose measurement capability unexpectedly. Note that battery models use LCD display only; LED display requires external power (24 VDC, 220 VAC, or 380 VAC).

Yes. With the “S” additional option code, the HM40 can be configured with 4–20 mA analog output, 0–5 VDC output, or RS485 digital output for integration with data loggers, PLCs, or SCADA systems. Note that signal output requires external power supply (V2, V3, or V4 models) — battery-powered V1 models cannot support signal output due to power constraints.

The HM40 features built-in unit switching that allows you to toggle between common pressure units including kPa, MPa, bar, mbar, psi, and kg/cm² directly from the front panel buttons. This makes it convenient for international teams or applications where different pressure unit standards are used. The unit conversion is handled by the microprocessor with no loss of measurement accuracy.

Standard configurations (common ranges, V1/V2 power options, standard connections) typically ship within 5–7 business days. Custom orders — including special dial sizes, non-standard process connections, high-temperature versions, or corrosion-resistant housings — require 10–15 business days. For volume orders (50+ units), contact our sales team for expedited production scheduling and competitive pricing.

Need a Digital Pressure Gauge Solution?

Tell us your pressure range, accuracy requirements, and application details. Our engineers will recommend the optimal HM40 configuration for your specific needs.

Our engineers typically respond within 12 business hours.

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HM SERIES — DIGITAL PRESSURE GAUGE

HM40 Digital Pressure Gauge

Product Overview

Technical Specifications