Compact Liquid Differential Pressure Transmitter | PMD440
Compact, Inline Stainless Steel Differential Pressure Transmitter for Liquids & Gases
The PMD440 Series is a heavy-duty, compact differential pressure sensor designed for inline installation in liquid flow, hydraulic system, pump protection, and industrial gas applications. Engineered with high-stability sensing technology and all-stainless steel wet parts (316L optional), the PMD440 reliably measures differential pressure across filters, valves, and heat exchangers.
Offering extreme versatility in tight spaces, it is available with standard Hirschmann connectors, M12 aviation plugs, submersible IP68 cable outlets, or local digital displays.
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Key Applications: Hydraulic pressure drop, pump inlet/outlet monitoring, liquid filter clogging detection, chiller water systems, and industrial automation equipment.
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Pressure Ranges: Broad range coverage from 0–10 kPa (0.1 bar) up to 0–3.5 MPa (35 bar / 500 psi).
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Output Options: 4–20 mA (with optional HART protocol), 0–10 V (customizable voltage), or RS485 Modbus digital output.
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Enclosure & Protection: Compact inline design with IP65 standard protection, customizable up to IP66 or IP68 submersible ratings.
Description
Robust Liquid & Gas Pressure Drop Measurement in a Compact Footprint
The PMD440 Compact Differential Pressure Transmitter provides a space-saving, high-reliability solution for measuring pressure differentials in pressurized liquid and gas systems. Unlike bulkier process-flanged transmitters, the PMD440 features a compact inline body with dual threaded process ports, allowing direct installation onto manifold blocks, pipe lines, and machinery frames without requiring heavy mounting brackets.
Superior Stability & High Accuracy Options
Built with advanced piezoresistive sensing cores, the PMD440 offers standard 0.25% FS accuracy, with custom options reaching 0.1% FS high precision. Integrated temperature drift compensation ensures dependable zero-point stability across changing fluid temperatures from -40°C to +80°C.
Specialized Models for OEM Integration & Harsh Environments
The PMD440 series offers six distinct sub-configurations to suit your specific physical and electrical requirements:
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PMD4401 / PMD4402: Standard Hirschmann or waterproof metal gland connections for general industrial machinery.
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PMD4403: Specialized small-range differential pressure version featuring an incredible 500x overload resistance for high-risk single-sided overpressure environments.
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PMD4404: Compact aviation socket connection with barbed hose fittings for light pneumatic/gas systems.
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PMD4405: Submersible IP68 waterproof cable outlet designed for liquid level monitoring and wet sumps.
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PMD4406: Flameproof/Explosion-proof housing featuring an integrated 4-digit LED/LCD digital display for local field readouts.
Additional information
| Model / Connection Type | Aviation Socket & Hose Barb (PMD4404), Explosion-Proof w/ Digital Display (PMD4406), High Overload Micro-DP (PMD4403), Standard Hirschmann DIN (PMD4401), Submersible IP68 Cable Outlet (PMD4405), Waterproof Metal Gland (PMD4402) |
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Features
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Compact & Easy Installation: Direct inline thread mounting saves space in OEM machinery and tight pipe galleries.
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Wide Span Coverage: Pressure ranges from 0–10 kPa (100 mbar) up to 3.5 MPa (35 bar / 500 psi).
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High-Precision Performance: 0.25% FS typical accuracy, with optional 0.1% high-accuracy calibration.
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High Overload Protection: Standard 2x FS overload rating, with specialized micro-DP models supporting up to 500x overload immunity.
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Flexible Signal Interfaces: 4–20 mA (HART compatible), 0–10 V (or custom voltage), and digital RS485.
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Versatile Electrical Connections: Hirschmann DIN socket, M12 aviation plug, direct cable output, or IP68 submersible cable.
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Extensive Process Thread Options: Available in G1/4, G1/2, NPT threads (1/4 NPT, 1/2 NPT), metric threads, and custom fitting sizes.
Specification
| Parameter | Technical Specification PDF |
| Measurement Medium |
Liquids, dry/wet gases, and water systems compatible with 316L SS |
| Pressure Ranges |
0–10 kPa … 3.5 MPa (0–0.1 bar to 0–35 bar / 0–500 psi) |
| Overload Capability |
≤ 2x Full Scale (Up to 500x for specialized PMD4403 model) |
| Accuracy Class |
±0.25% FS (Typical), ±0.1% FS (Custom High-Precision), ±0.5% FS (Max) |
| Long-Term Stability |
±0.1% FS / year (Typical), ±0.2% FS / year (Max) |
| Thermal Drift |
Zero/Sensitivity: ±0.03% FS/°C (≤100 kPa), ±0.02% FS/°C (>100 kPa) |
| Operating Temperatures |
Medium: -40°C to +80°C | Compensation: 0°C to +50°C (≤100kPa), -10°C to +70°C (>100kPa) |
| Power Supply |
12 to 30 VDC |
| Output Signals |
4–20 mA (HART protocol option), 0–10 VDC, or RS485 Modbus |
| Protection Rating |
IP65 (Standard), Customizable IP66 / IP68 (PMD4405) |
| Process Connections |
G1/4, G1/2, 1/4 NPT, 1/2 NPT, M20x1.5, M14x1.5, M12, etc. |
| Wetted Materials |
316L Stainless Steel |
FAQ
1. What liquids can the PMD440 differential pressure transmitter measure?
The PMD440 is compatible with water, hydraulic oils, glycol solutions, fuels, and non-corrosive industrial liquids that do not react with 316L stainless steel wet parts.
2. How does the PMD440 differ from the PMD3051 process transmitter?
The PMD440 is a compact, inline transmitter designed for space-constrained equipment, pump manifolds, and hydraulic lines using threaded pipe connections. The PMD3051 is a heavy process transmitter with large coplanar flanges, high static pressure resistance (up to 41 MPa), and ATEX explosion-proof ratings for refineries and high-temperature steam loops.
3. What should I do if my system experiences high one-way overpressure spikes?
For applications where temporary one-way overpressure is common (such as during system startup or valve switching), we recommend installing a standard 3-valve or 5-valve manifold block, or choosing the PMD4403 variant which features built-in overload protection up to 500 times full scale.
4. Can the PMD440 be submerged underwater?
Yes. By choosing the PMD4405 configuration, the transmitter is built with an IP68-rated waterproof cable outlet, making it suitable for submerged liquid level and pit differential pressure monitoring.
