HM1151 Capacitive Differential Pressure Transmitter

Industrial-grade pressure measurement with dual-chamber δ-cell design for reliable 4–20mA output across extreme conditions.

MAX RANGE

40 MPa

ACCURACY

±0.25%

OUTPUT

4–20mA

CERTIFIED

Ex-Proof

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HM1151 Capacitive Differential Pressure Transmitter

Product Overview

The HM1151 is a capacitor-type differential pressure transducer engineered for demanding industrial environments. Its advanced dual-chamber δ-cell design uses imported measurement technology to convert process pressure into precise 4–20mA output signals.

The measurement principle works by transferring process pressure to a central measuring membrane, which displaces by approximately 0.1mm under full scale. This membrane displacement converts directly to differential capacitance, which is then amplified and transformed into a stable 4–20mA current output. This design eliminates moveable mechanical parts, resulting in exceptional reliability and minimal maintenance requirements.

Trusted across petroleum, chemical, metallurgical, power generation, food processing, paper manufacturing, pharmaceutical, and mechanical industries, the HM1151 delivers high accuracy (±0.25%FS), excellent stability, and superior overload protection (500% positive, 600% negative immigration) for mission-critical applications.

Technical Specifications

ParameterSpecification
Measuring Range0–0.125 KPa to 0–40 MPa (16 standard ranges)
Signal Output4–20mA, 2-wire or 4-wire system
Power Supply12–45V DC (24V DC typical)
Load ResistanceRL ≤ 50(VS−12)Ω
Accuracy±0.25%FS or ±0.5%FS (selectable)
Operating TemperatureAmplifier: −29 to +93°C (LT type: −25 to +70°C); Element: −40 to +104°C; High-temp option: +15 to +315°C
Static Pressure Rating4, 10, 25, or 32 MPa
Humidity0–100% RH (non-condensing)
Response Time0.2–1.67s (adjustable damping)
Dead ZoneNone (≤0.1%)
StabilityWithin basic tolerance for 6 months
Vibration Resistance±0.05%/g at 200Hz
Temperature InfluenceMax scale: ±0.1%/55°C (total ±0.15%/55°C); Min scale: ±0.1%/55°C (total ±0.2%/55°C)
Process Connection1/4″–18NPT, 1/2″–14NPT, or custom
Signal ConnectorG1/2 (DIN 43650C optional)
Weight~5.4 kg
Membrane Materials316L stainless steel, Hastelloy C, Monel, Tantalum (corrosion-resistant options)
Flange MaterialsElectroplated carbon steel, 316L stainless steel, Hastelloy C, Monel
SealingNBR or Fluorubber O-rings

Key Features

Dual-Chamber δ-Cell Design

Advanced measurement technology converts process pressure to differential capacitance with ~0.1mm membrane displacement.

Wide Range Coverage

16 standard measuring ranges from 0.125 KPa to 40 MPa accommodate virtually any industrial pressure measurement need.

Certified Explosion-Proof Design

Type d II BT4 and intrinsically safe II CT6 certifications enable safe operation in hazardous classified zones.

Low Maintenance

No moveable parts eliminate the need for routine maintenance while ensuring consistent performance over extended operational periods.

Corrosion-Resistant Materials

Optional membrane materials including 316L stainless, Hastelloy C, Monel, and Tantalum resist aggressive chemical environments.

Adjustable Damping

Response time adjustment (0.2–1.67s) allows tuning to match process dynamics and eliminate noise-induced fluctuations.

Industrial Applications

Oil & Gas Processing

Reliable pressure monitoring for crude processing, refining operations, and pipeline transport with explosion-proof certification.

Chemical Plants

Process monitoring with corrosion-resistant materials for aggressive chemical environments and temperature extremes.

Power Generation

Steam pressure measurement and boiler monitoring for thermal and nuclear facilities requiring high stability and precision.

Water & Wastewater

Flow and filtration pressure control in municipal and industrial water treatment systems with proven long-term reliability.

Pulp & Paper

Bleaching and pressing process monitoring with stable 4–20mA output for integrated control systems.

Food & Beverage

Sanitary applications with stainless steel design for processing, packaging, and cold-chain management systems.

Ordering Guide

The HM1151 is offered in a full series with interchangeable components, allowing you to configure the transmitter for your specific application requirements.

Measuring Range Options

Range Code Measuring Range
10–0.125 KPa
20–0.25 KPa
30–0.5 KPa
40–1 KPa
50–2.5 KPa
60–5 KPa
70–10 KPa
80–25 KPa
90–40 KPa
100–100 KPa
110–250 KPa
120–1 MPa
130–2.5 MPa
140–10 MPa
150–25 MPa
160–40 MPa
CustomCustom ranges available on request

Material & Configuration

Component Options
Membrane316L stainless, Hastelloy C, Monel, Tantalum
FlangeElectroplated carbon steel, 316L, Hastelloy C, Monel
SealingNBR or Fluorubber
Connection1/4”–18NPT, 1/2”–14NPT, custom
Signal Output4-wire 4–20mA standard
OptionalExplosion-proof (Type d II BT4 or II CT6)

Frequently Asked Questions

The δ-cell (dual-chamber design) uses two identical sensing chambers separated by a central measuring membrane. Process pressure enters the primary chamber and pushes against the membrane. A reference pressure (typically atmospheric or sealed vacuum) acts on the opposite side. The resulting membrane displacement—typically 0.05–0.1mm at full scale—converts to a change in capacitance between the membrane and fixed electrodes. This differential capacitance is then amplified and converted to 4–20mA output. This design offers excellent linearity and low noise because the symmetric geometry cancels common-mode environmental influences like temperature variations.

The HM1151 is available in two accuracy classes: ±0.25%FS (higher precision) or ±0.5%FS (standard). %FS refers to percentage of full scale. For example, on a 0–10 MPa range, ±0.25%FS = ±25 kPa accuracy, while ±0.5%FS = ±50 kPa accuracy. The ±0.25% version costs slightly more but is recommended for critical control loops where tighter tolerance bands improve process stability and product quality. The ±0.5% version is suitable for monitoring and alarm functions where ±1–2% total system error (including transmitter + wiring) is acceptable.

The HM1151 membrane—the sensor’s critical interface with process media—is available in standard 316L stainless steel or upgraded options: Hastelloy C (excellent for chlorine, sulfuric acid), Monel (seawater, hydrogen sulfide), or Tantalum (extremely aggressive environments). Choosing the right material prevents stress-corrosion cracking, pitting, and crevice corrosion that would degrade accuracy or cause catastrophic failure. For example, in paper bleach plants (chlorine dioxide), Hastelloy C extends service life from 12 months (316L) to 3+ years. Consult application-specific corrosion charts or our technical team when handling acids, bases, chlorinated water, or dissolved sulfides.

The HM1151 is an analog 4–20mA transmitter—ideal for legacy process control systems and installations without HART or digital networks. The HM3051 is a “smart” transmitter with digital protocols (HART) enabling remote configuration, diagnostics, and integration with modern DCS/SCADA systems. Choose HM1151 if your facility uses analog 4–20mA infrastructure; choose HM3051 if you need predictive maintenance data, remote diagnostics, or digital integration. Both share the same dual δ-cell measurement principle and corrosion-resistant materials; the main difference is output interface and optional embedded intelligence.

Install the HM1151 with the impulse ports pointing downward for gas media (to prevent liquid pooling in sensing lines) or upward for liquid media (to prevent air bubbles). Use snubbers or damping adjustment (0.2–1.67s tunable) if the process exhibits pressure spikes or oscillations. Ensure supply voltage is stable within 12–45V DC range; voltage fluctuations exceed 0.005%/V power sensitivity. Vent any enclosed fluid lines to atmospheric pressure before commissioning to remove air pockets. For high-vibration environments (>2g RMS), use isolation mounts rated for the transmitter’s 5.4 kg weight and mount impulse tubing with rigid clamps and minimal slope changes. Always test the 4–20mA output (using a calibrator) after installation to verify zero and span adjustment if needed.

Yes. The HM1151 features external, continuously adjustable range and zero via front-panel potentiometers or remote pulse input (model-dependent). This allows field recalibration to match revised process requirements (e.g., changing a 0–10 MPa transmitter to 0–25 MPa output without hardware replacement). Range adjustment accommodates up to 500% positive and 600% negative immigration (overpressure span), protecting against transient spikes that would otherwise destroy less robust sensors. Always perform range/zero adjustments under static process conditions using a calibrated pressure source and multimeter, and document the as-found settings before making changes for traceability.

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