HM SERIES — SAPPHIRE SENSING TECHNOLOGY

HM28 Sapphire Pressure Transmitter

Mono-crystalline silicon-sapphire sensor with titanium diaphragm — delivering zero hysteresis, no fatigue or creep, and complete P-N junction drift immunity. Measures up to 260 MPa across media temperatures from -65°C to +200°C for aerospace, nuclear, offshore, and extreme-environment applications.

260 MPa Max Range  |  ±0.1% FS Accuracy  |  -65°C to +200°C Media Temp  |  Titanium Diaphragm

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HM28 Sapphire Pressure Transmitter

Product Overview

The HM28 sapphire pressure transmitter utilizes a German HMK mono-crystalline sapphire sensor element with titanium diaphragm, delivering exceptional measurement performance across extreme pressure ranges up to 260 MPa. The sapphire sensing technology provides inherent advantages over conventional silicon piezoresistive sensors: zero hysteresis, no fatigue or creep, superior insulation characteristics, and complete immunity to P-N junction drift.

With an operating media temperature range of -65°C to +200°C, strong radiation immunity, and titanium-sapphire corrosion resistance, the HM28 is the preferred choice for demanding applications in aerospace, nuclear power, offshore marine, petroleum refining, and scientific research. The sensor maintains ±0.1% FS/year long-term stability while offering three selectable accuracy grades down to ±0.1% FS.

Technical Specifications

high-temperature-pressure-transducer

Key Features

Sapphire Sensor Technology

Mono-crystalline silicon-sapphire sensing element eliminates hysteresis, fatigue, and creep — delivering exceptional repeatability and long-term measurement integrity that silicon sensors cannot match.

Wide Media Temperature Range

Operates with process media from -65°C to +200°C, far exceeding conventional silicon piezoresistive sensors limited to 125°C. Ideal for cryogenic and high-temperature processes.

Ultra-High Pressure Capacity

Measures up to 260 MPa (37,700 psi) — suitable for hydraulic testing, deep-well applications, and ultra-high-pressure industrial processes beyond standard transmitter limits.

Radiation Immunity

Silicon-sapphire semiconductor element provides inherent radiation resistance without P-N junction drift, making it ideal for nuclear facilities, research reactors, and irradiation environments.

Titanium Diaphragm

Titanium-sapphire wetted membrane offers superior corrosion resistance against aggressive chemicals, seawater, hydrogen sulfide, and high-temperature media encountered in offshore and chemical processing.

0.1% FS Long-Term Stability

Annual drift of just ±0.1% FS ensures reliable, maintenance-free operation in critical measurement loops. Reduces recalibration frequency and total cost of ownership.

Application Scenarios

Engineered for the most demanding environments where conventional sensors fall short.

Aerospace & Defense

Flight control hydraulic systems, rocket propulsion testing, aircraft engine monitoring, and satellite environmental testing. Sapphire sensor withstands extreme vibration and temperature cycling.

Nuclear Power Generation

Reactor coolant pressure monitoring, primary loop measurement, and radiation-exposed environments requiring P-N drift immunity that only sapphire sensors can provide.

Offshore & Marine

Subsea pressure measurement, ballast tank monitoring, and shipboard hydraulic systems. Titanium diaphragm resists saltwater corrosion and biofouling.

Petroleum & Chemical Processing

High-temperature reactor vessel pressure, catalytic cracking units, and corrosive chemical process streams. Withstands H₂S, acids, and aggressive solvents.

Scientific Research & Calibration

Laboratory reference measurement, materials testing under extreme pressure, and metrology calibration applications requiring zero-hysteresis performance.

Food & Pharmaceutical

Hygienic process pressure monitoring in sterilization, pasteurization, and clean-in-place (CIP) systems. Titanium diaphragm meets food-contact material standards.

Ordering Guide

Code PositionOptions
Pressure TypeG = Gauge (default); A = Absolute
RangeSpecify: 0–X kPa or 0–X MPa (max 260 MPa)
Accuracy Code1 = ±0.4% FS; 2 = ±0.25% FS; 3 = ±0.1% FS
Output CodeA1 = 4–20 mA; V1 = 1–5 V DC; V2 = 0–5 V DC; V3 = 0.5–4.5 V DC
Connection CodeF1 = M20×1.5; F2 = G1/4; F0 = Special; P = Flush diaphragm
Cable CodeW1 = Cable type IP67 (2 m); W2 = DIN 43650 plug IP65
OptionsE = Ex ia II CT5 intrinsic safety

Example: HM28 A (0–1.0 MPa) — 2 — A1 — F1 — W1 — P = Sapphire transmitter, absolute, 0–1 MPa, ±0.25% FS, 4–20 mA, M20×1.5, cable IP67, flush diaphragm.

HM26 Ceramic Capacitive Pressure Transmitter

HM26 Ceramic Capacitive

High-temperature ceramic capacitive sensor for demanding process environments up to 150°C. Al₂O₃ diaphragm, 0.5 kPa–100 MPa, 0.1% FS accuracy.

HM22 High Accuracy Pressure Transmitter

HM22 High Accuracy

German-engineered 0.075% FS precision transmitter for laboratory and reference measurement applications requiring exceptional repeatability.

HM90 High-Frequency Dynamic Pressure Transmitter | 2MHz | 1μs

HM90 High-Frequency Dynamic Pressure Transmitter

Ultra-fast response for blast, combustion, and hydraulic pulse measurement. 2 MHz bandwidth with 1 μs rise time.

Frequently Asked Questions

Sapphire sensors use mono-crystalline silicon insulated on a sapphire substrate, which eliminates hysteresis, fatigue, and creep that affect conventional silicon sensors. The sapphire substrate provides excellent electrical insulation and thermal stability. Additionally, silicon-sapphire elements do not suffer from P-N junction drift, ensuring long-term measurement accuracy even in radiation environments.

The HM28 supports measuring ranges up to 260 MPa (approximately 37,700 psi), making it one of the highest-capacity pressure transmitters in our product line. For pressures up to 10 MPa, overload capacity is 2× full scale; for higher ranges, overload capacity is 1.5× full scale.

Yes, the silicon-sapphire sensing element has inherent radiation immunity characteristics, making the HM28 well-suited for nuclear power generation, research reactors, and other radiation-exposed environments where conventional sensors would experience drift or degradation over time.

The standard HM28 supports media temperatures from -65°C to +150°C with full compensation from -40°C to +120°C. Extended temperature variants can operate with media up to +200°C. The titanium-sapphire diaphragm ensures compatibility with both cryogenic and high-temperature media — see how sapphire compares to other high-temperature pressure transducer methods.

Yes, the HM28 features a titanium-sapphire diaphragm and 316-equivalent stainless steel enclosure, providing excellent corrosion resistance. It is compatible with all liquids and gases that are compatible with titanium alloy and stainless steel, including aggressive chemicals, seawater, and high-temperature process fluids.

Need a Sapphire Pressure Transmitter?

Tell us about your application requirements. Our engineers will recommend the best HM28 configuration for your process conditions — typically within 24 hours.

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