RTD and thermocouple assemblies with integrated 4–20 mA transmitters for precise supply/return monitoring across every liquid cooling loop.
Supply and return coolant temperatures are the two variables that define cooling capacity and efficiency. Sub-degree accuracy is required to calculate thermal duty (Q = ṁ · cp · ΔT) with any confidence, and to trigger timely high-temperature protection upstream of IT hardware.
Supmea's SUP-WZP Pt100/Pt1000 RTD sensors and SUP-SBWR transmitters cover the full range of data center thermal monitoring — from facility water loops at +5 °C to two-phase immersion tanks at +60 °C, with ATEX variants for adjacent hazardous areas.
| Sensor type | Pt100 / Pt1000 platinum RTD, IEC 60751 Class A or AA |
|---|---|
| Temperature range | −50 °C to +200 °C (standard); −200 °C to +600 °C (extended) |
| Accuracy (Class A) | ±(0.15 + 0.002·|t|) °C |
| Accuracy (Class AA) | ±(0.10 + 0.0017·|t|) °C |
| Response time (τ₀.₅) | ≤ 4 seconds in moving water |
| Wiring configuration | 2-, 3-, or 4-wire |
| Sheath material | 316L stainless steel (standard); Hastelloy, titanium available |
| Sheath diameter | 3 mm, 4 mm, 6 mm, 8 mm, 10 mm |
| Insertion length | 50 – 2000 mm (custom lengths available) |
| Process connection | G½″, G¾″, NPT½″, M20×1.5, sanitary tri-clamp |
| Thermowell options | Drilled bar stock, 316L/duplex/Inconel, PN40 / PN100 |
| Enclosure rating | IP65 / IP68 (for integrated head) |
| Vibration resistance | IEC 60068-2-6, 4g @ 10–500 Hz |
| Approvals | CE, RoHS; ATEX Ex ia IIC T6 (Ex variant) |
| Input | Pt100/Pt1000 RTD, J/K/E/T/N/R/S/B thermocouple |
|---|---|
| Output | 4–20 mA (2-wire), HART 7 (option), RS-485 Modbus |
| Digital accuracy | ±0.05% of span |
| Ambient temperature | −40 °C to +85 °C |
| Supply voltage | 10.5 – 42 VDC |
| Configuration | PC via HART modem, NFC, or DIP switches |
| Galvanic isolation | 500 VAC input-to-output |
| Sensor fault detection | Upscale / downscale / hold / last-value |
Typical deployment points in data center liquid cooling architectures — from facility water through to rack-level manifolds.
4-wire Class A Pt100 sensors at CDU supply and return ports deliver the ΔT accuracy needed for thermal capacity calculation and per-rack cooling SLAs in colocation environments.
Compact 3 mm sheath sensors with M8/M12 quick-connect fit directly into cold plate block manifolds, enabling per-GPU thermal telemetry in AI cluster deployments.
Multi-point RTD strings measure vertical thermal stratification in single-phase immersion tanks — essential for tuning circulation pump flow and validating tank-level CFD models.
Pt100 sensors on chiller supply headers provide the feedback signal for chiller setpoint control, with tight accuracy required to operate at ASHRAE W32/W40 warmer supply temperatures.
Paired sensors across RDHx and dry cooler heat exchangers measure approach temperatures — an early indicator of fouling, air-side blockage, or refrigerant loss.
IP68-rated compact sensors with 30 m cables enable dense rack-level thermal telemetry for hot-spot identification and airflow management in hybrid air/liquid rooms.
Send us a P&ID or a short description of your cooling loop. Our application engineers respond with a specification recommendation and quote within one business day.
The questions we hear most often from specifying engineers, system integrators, and facility operators.
Pt100 is the traditional industrial standard and the default for most data center BMS integrations. Pt1000 has 10× higher resistance, which makes cable resistance errors proportionally smaller — a meaningful advantage for long cable runs (>20 m) or when only 2-wire wiring is feasible. For new greenfield designs with 4-wire wiring and run lengths under 15 m, either is fine. For retrofits reusing existing 2-wire cabling over long distances, prefer Pt1000.
For ΔT-based capacity calculation across a loop, what matters most is the matched accuracy between supply and return sensors, not the absolute accuracy of either. For typical data center applications, matched Class A Pt100 pairs (calibrated together) give you better real-world ΔT accuracy than unmatched Class AA sensors at a lower cost. Class AA is justified when you need audit-grade absolute temperature measurement (SLA reporting, white-box thermal validation).
Direct-insertion RTDs have faster response (τ₀.₅ ≈ 4 s vs. 15–30 s with a thermowell) and lower cost, but require draining the loop for removal or replacement. For primary facility loops — which you cannot drain without major operational disruption — always specify thermowells. For secondary loops at the CDU and below, direct insertion with isolation valves is acceptable and preferred for response time.
For simple BMS integration with one measured variable per sensor, 4–20 mA is the proven default. HART adds diagnostic data and secondary variables on the same two wires with virtually no downside. RS-485 Modbus makes sense when you are daisy-chaining 10+ sensors on a single trunk (typical in immersion tank multi-point monitoring) — you save on DCS/PLC analog input channels. Avoid mixing protocols within one loop if you can.
The IP68 versions of the SUP-WZP series are rated for continuous submersion to 1 m, 24 h. For immersion cooling applications where the sensor head sits in dielectric fluid, specify the fully-potted IP68 head or use a thermowell-mounted transmitter with the head outside the tank. Standard IP65 heads are not suitable for direct immersion.
Platinum RTDs are inherently stable — drift is typically <0.05 °C/year under normal operating conditions. For commercial data center applications, 2-year recalibration intervals are standard. For hyperscale sites with PUE audit requirements, annual calibration is common. We provide factory recalibration with ILAC-traceable certificates.
Response time depends far more on thermowell wall thickness and sensor sheath diameter than on the sensor element itself. A 3 mm bare sheath in moving water reaches τ₀.₅ ≈ 4 s. A 6 mm sensor in a standard stepped thermowell reaches τ₀.₅ ≈ 20 s. For fast-loop control (cold plate outlet protection), use small-diameter direct-insertion sensors.
Whether you're designing a new liquid-cooled data center or retrofitting existing air-cooled facilities, our engineers can help you select the right instrumentation package.