Non-contact ultrasonic and guided wave radar level sensors for every coolant reservoir, expansion tank, and immersion dielectric bath.
Reliable level measurement is the foundation of coolant inventory tracking, leak detection, and pump protection. A sudden drop in reservoir level is often the only real-time indicator of a loop breach, and gradual drift reveals evaporation, seepage, or fluid migration to immersion loads that would otherwise go undetected.
Supmea's SUP-R200 guided wave radar and SUP-U200 ultrasonic level transmitters deliver non-contact, drift-resistant measurement across the full spectrum of data center coolant containment — from small expansion tanks to large immersion tubs with changing fluid properties.
| Measurement principle | Time-domain reflectometry (guided microwave) |
|---|---|
| Measuring range | 0.1 – 30 m |
| Accuracy | ±3 mm or 0.05% of range (whichever greater) |
| Frequency | 1.6 GHz |
| Process temperature | −40 °C to +250 °C (standard probe) |
| Process pressure | Vacuum to 4 MPa (standard); 40 MPa (high-pressure option) |
| Dielectric constant (εr) | ≥ 1.4 (sensitive to low-ε dielectric fluids) |
| Probe type | Single-rod, twin-rod, coaxial, flexible cable |
| Probe material | 316L SS, Hastelloy C-276, PTFE-coated |
| Output | 4–20 mA HART, RS-485 Modbus, HART-to-Ethernet option |
| Enclosure | Die-cast aluminum, IP67 |
| Approvals | CE, RoHS; ATEX Ex ia IIC T6 |
| Measurement range | 0.3 – 15 m (standard); up to 40 m (extended) |
|---|---|
| Accuracy | ±0.25% of range |
| Beam angle | 5° – 8° |
| Temperature compensation | Automatic, via integrated sensor |
| Process temperature | −20 °C to +80 °C at transducer face |
| Output | 4–20 mA, RS-485 Modbus, relay contacts |
| Dead zone | 0.2 – 0.4 m depending on range |
| Display | Integrated LCD with menu configuration |
Typical deployment points in data center liquid cooling architectures — from facility water through to rack-level manifolds.
Guided wave radar handles the low dielectric constant (εr ≈ 2) of synthetic dielectric fluids like GRC ElectroSafe, where ultrasonic sensors would suffer from weak reflection. Flange-mounted TDR probes integrate cleanly into open-top immersion tanks.
Compact ultrasonic transmitters on sealed CDU coolant reservoirs track makeup requirements and trigger low-level pump protection. Non-contact operation avoids probe fouling from glycol oxidation products.
Low-range TDR or ultrasonic transmitters on closed-loop expansion tanks monitor the air-water interface for makeup water valve control and leak alarming.
Long-range ultrasonic transmitters on outdoor makeup water tanks track consumption and trigger replenishment orders, integrated with the facility water management system.
High-sensitivity radar on two-phase immersion coolant condenser sumps measures condensate return rate — an indirect indicator of boiling rate and IT load.
Continuous level monitoring on heat exchanger sumps and chiller evaporator headers supports proactive leak detection and refrigerant charge verification.
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.
Guided wave radar is superior for dielectric immersion fluids (low εr), for vapor-rich environments (two-phase immersion), for tanks with internal obstructions or agitation, and for any application where absolute accuracy below 0.5% matters. Ultrasonic is the cost-effective choice for open-top water tanks, makeup reservoirs, and relatively quiet coolant tanks where line-of-sight to the liquid surface is unobstructed. If in doubt, TDR is the more forgiving technology.
Yes, with caveats. Synthetic dielectric fluids have εr values in the 1.8–2.5 range, which is within but near the lower limit of TDR sensitivity. For reliable measurement, specify the twin-rod or coaxial probe variant (not single-rod), and ensure the probe length is configured with the correct empty-tank reference. Our application engineering reviews each immersion fluid and tank geometry before quoting.
Internal obstructions can cause false echoes on both technologies. TDR with a coaxial probe is essentially immune because the measurement volume is confined inside the outer tube. For ultrasonic, position the transducer to avoid line-of-sight obstructions and use the mapping feature to exclude known echoes. In heavily obstructed tanks, coaxial TDR is the only reliable option.
Ultrasonic transmitters compensate automatically for air-path temperature via an integrated sensor at the transducer face, which is the dominant error source for ultrasonic. TDR is essentially insensitive to process temperature within the specified range because it measures time-of-flight of a guided microwave pulse, which propagates at the speed of light regardless of fluid temperature.
Both ultrasonic and TDR are essentially maintenance-free for data center coolant applications. Ultrasonic transducer faces should be checked annually for condensation or particulate buildup; TDR probes in glycol service may develop a thin coating over 5+ years which typically does not affect accuracy. No moving parts, no consumable seals — contrast with float or displacer technologies.
Ultrasonic has a 'dead zone' near the transducer (typically 0.3–0.4 m) and requires at least 0.5 m of clear range below that. TDR has a much smaller blind zone (50–100 mm at the flange and probe tip) and works reliably in tanks down to 300 mm tall. For expansion tanks under 500 mm tall, always specify TDR.
Yes — we offer vibrating fork, conductivity, and optical point-level switches as complementary products. For data center applications, a continuous TDR or ultrasonic transmitter plus a high-high and low-low vibrating fork switch (independent of the transmitter) is the recommended architecture for combined level control and safety interlock.
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.