Differential Pressure Transmitter
Series: 988
BENEFITS
The 988 series are robust differential pressures transmitters for liquid and gaseous, non-flammable, non-aggresive media, designed to measure differential pressure as well as under- and overpressure. A ceramic AL2O3 measuring cell with Parylene C coating and internal PTC temperature compensation delivers stable, long-term accuracy in demanding thermal and mechanical environments. Outputs include 4-20mA (2-wire/3-wire) and 0-10V (3-wire) for seamless integreation into PLCs, BMS, and process controllers.
FEATURES
Rugged sensing core — Ceramic cell with Parylene C resists wear and delivers low hysteresis, high repeatability, and minimal drift for dependable measurements over time.
Wide electrical compatibility — 2‑wire 4–20 mA for simple loop retrofits; 3‑wire 0–10 V/4–20 mA for multi‑signal control and monitoring, reducing gateway complexity.
Thermal resilience — Medium temperatures from –20…+105 °C (short‑term 120 °C) and ambient –20…+85 °C enable hot/cold loop applications without extra protection.
Installation flexibility — Choice of brass or stainless pressure chambers; DIN Form A or M12 connectors; accessories for L/S/U‑mounting simplify panel or pipework installs.
Industry integrations — Use in building automation, sanitary/industrial measurement, hydronic loops (supply/return), filter/fan/compressor monitoring, and cooling/heating circuits is already validated across your internal collateral
Building automation / HVAC
Δp feedback for pumps, coils and compressors; alarms for abnormal pressure changes to drive predictive maintenance.
Hydronic heating & cooling
Measure Δp between supply and return to verify coil performance, detect air/fouling, and optimize pump head for energy savings.
Filter monitoring (air/liquid)
Rising Δp indicates fouling; timely service prevents contamination and cuts pump energy.
Fans & compressors
Monitor Δp to confirm airflow setpoints, detect obstructions/leaks, and protect rotating equipment.
Cooling systems (HVAC/industrial)
Δp trending across coolers/plate heat exchangers highlights degradation early for planned intervention.
Pressure range
For an optimal adaptation to the application, different pressure ranges are available. The measurement is carried out by a ceramic pressure measuring cell, temperature-compensated via internal PTC.
Output signal
In the 3-wire version there is an output signal of 0 … 10 V, or 4 … 20 mA available. For the 2-wire version the transmitter provides an output signal of 4 … 20 mA.
Electrical connection
The electrical connection of the transmitter is optionally available with a 4-pin standardized device plug according to DIN EN 175301 Form A, or with a 4-pin M12 flange plug, A-coded, according to DIN EN 61079.
Why Differential Pressure Measurement Matters in Modern Data Center Cooling
Key Benefits
- ensures consistent cooling performance for every server, even as rack configurations change
- maintains the correct flow across cold plates under all operating conditions
- protects GPUs and processors from overheating caused by insufficient flow
- prevents excessive flow that can damage cold plate channels and reduce system efficiency
- keeps cooling performance stable without manual adjustments
- reduces the risk of downtime by providing a predictable and reliable cooling environment
- delivers fast, accurate feedback to the control system for precise regulation
- supports high-density racks running at 100kW and beyond with consistent thermal performance
Accessories
Metal mounting bracket set L-Form
Bracket + 2 screws M4x6.5mm)
Metal mounting bracket set U-Form
Bracket + 2 screws M4x6.5mm)
Metal mounting bracket set S-Form
Bracket + 2 screws M4x6.5mm)
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Downloads
Specification Table
| Type | Details | 2-wire | 3-wire | 3-wire |
|---|---|---|---|---|
| Standard measuring ranges designed at pressure level PN 40 Special Ranges available upon request | 0-2 bar 0-6 bar 0-10 bar | ■ | ■ | ■ |
| Pressure Measuring Cell | Ceramic cell Al2O3 with Parylene C coating | ■ | ■ | ■ |
| Nominal Voltage | 24 VDC | 24 V AC/DC (50-60 Hz) | 24 V AC/DC (50-60 Hz) | |
| Operating Voltage | 18 – 30 VDC | 18 – 25 VAC 18 – 30 VDC | 18 – 25 VAC 18 – 30 VDC |
|
| Power Consumption | < 0.51 W (VA) | < 1.2 W (VA) | < 1.2 W (VA) | |
| Output Singal | Linear: 14 bits resolution | 4-20 mA | 4-20 mA | 0-10 V |
| Output Load | ≤ 400 Ω @ 24 VDC | ≤ 600 Ω @ 24 VDC ≤ 400 Ω @ 24 VAC | ≥ 1 kΩ | |
| Medium temperature (Media not freezing or with suitable frost protection) | -20 … +105°C (for a short time 120°C) | ■ | ■ | ■ |
| Ambient Operating Temperature | -20 … +85°C | ■ | ■ | ■ |
| Storage Temperature | -50 … +125°C | ■ | ■ | ■ |
| Total Error-/Char. Curve deviation (FS pressure cell) In the adjusted temperature range* *incl. non-linearity, hysteresys and reproducibility | ≤ ±1.5% @ -20 … +85°C | ≤ ±1.0% @ -20 … +85°C | ≤ ±1.0% @ -20 … +85°C |
|
| Accuracy measuring cell (FS pressure cell*) *incl. non-linearity, hysteresys and reproducibility | ±0.4% (typ.) / ±1.0% (max.) | ■ | ■ | ■ |
| Hysteresis pressure cell Repeatability of the pressure cell Long-Term drift pressure cell | ≤ ±0.2%FS ≤ 0.1%FS ≤ 0.3%FS/Year | ■ | ■ | ■ |
| Effect of voltage supply (FS) | < 0.04% / V | ■ | ■ | ■ |
| Effect of temperature (FS pressure cell) incl. electronic | ≤ 0.018% / K (typ.) ≤ 0.036% / K (max.) | ■ | ■ | ■ |
| Humidity | 0 - 95% rH (not-condensed) | ■ | ■ | ■ |
| Reference Conditions | EN 60770; 23°C | ■ | ■ | ■ |
| Clock Cycle Pressure Measurement | < 4 ms | < 2 ms | < 2 ms | |
| Response Time | 200 ms | 100 ms | 100 ms | |
| Standard Process Connection P1 and P2 | 2 x inner thread G1/4 Axial | ■ | ■ | ■ |
| Electrical Connection | Plug connector as per DIN 175301 Form A or M12 connector DIN EN 61079 A-coded | ■ | ■ | ■ |
| Materials | In contact with media: pressure chamber Brass / Stainless steel; EPDM O-ring No contact with media: NBR seal; Cover ABS black; Plug connector PA black | ■ | ■ | ■ |
| Weight | ca. 450 g | ■ | ■ | ■ |
| Protection Rating | IP65 (DIN EN 60529) | ■ | ■ | ■ |
| CE-Conformity | EN 61326 | ■ | ■ | ■ |
| UL-Authorization | UL 61010-1:2012 Ed.3 + R:06Jun2023 CSA C22.2#61010-1-12:2012 Ed.3 + U1;U2;A1;U3 | ■ | ■ | ■ |
| RoHS Conformity | 2011/65/EU | ■ | ■ | ■ |
