Overview
AI workloads have driven per-rack power from 5-15 kW to 50-150 kW, making liquid cooling (cold plate, immersion, in-row) the default for new hyperscale data centers. Loops run ethylene glycol (EG, 30-50 vol%) or propylene glycol (PG) in water. Too lean: dry coolers freeze and burst in winter (single incident worth millions plus SLA penalties). Too rich: viscosity rises, heat-transfer efficiency falls, pump energy +5-10%. PS7400 inline tuning-fork density monitors EG / PG concentration continuously — a core instrument for Alibaba, Tencent, ByteDance, Huawei and the three-carrier IDC operators. Same approach covers HVAC scenarios: metro ventilation chillers, commercial cooling, chemical cooling and ice-storage systems.
Process challenges
- EG concentration drifts continuously — water evaporation + glycol oxidation + operator top-up bias, accumulating 5-10% over 3-5 years
- IDC operators are network specialists, not chemists — monthly refractometer sampling can't catch drift
- Tier 3/4 facilities need long-life unmaintained sensors — instrument failure means downtime
- HVAC pipe sizes vary widely (DN50-DN200), needing flexible installation
- Glycol operates 5-45°C — automatic temperature compensation is mandatory
Recommended solutions
| Measurement point | Principle | Models |
|---|---|---|
| Liquid-cooled main loop EG / PG concentration | Tuning fork + PT1000 | PS7400 |
| Immersion-cooling dielectric fluid density | Tuning fork | PS7400 |
| Metro / commercial chiller secondary refrigerant | Tuning fork | PS7400 |
| Ice-storage brine concentration | Tuning fork / ultrasonic SoS | PS7400 / PS7020 |
