INDUSTRY 16

Data Center / HVAC Liquid Cooling

16 / DATA CENTER

Inline EG / PG concentration for AI liquid-cooled data centers — cold-plate and immersion, plus metro and commercial HVAC chiller applications.

1 applicable products 1 application cases

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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

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

Ethylene Glycol EG / Propylene Glycol PG Online Concentration Monitoring – Dual Optimization for Freeze Protection and Heat Transfer

In AI liquid-cooled data centers, long-term drift in the concentration of the ethylene glycol coolant has led to freezing and tube ruptures in dry coolers during winter, as well as reduced heat-transfer efficiency. The PS7400 online tuning fork concentration meter is directly installed in the primary circulation loop; leveraging its factory‑preset EG/PG concentration curve and PT1000 temperature compensation, it delivers sub‑second continuous monitoring with a concentration accuracy of ±0.5 vol%, enabling precise concentration control and reducing pump energy consumption by 6%.

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Industry FAQ

Do AI data centers need online ethylene glycol concentration monitoring?

It is necessary. AI data center liquid cooling (cold‑plate and immersion types) typically uses aqueous solutions of ethylene glycol (EG) or propylene glycol (PG), with concentrations ranging from 30% to 50%. The importance of precise concentration control: too low a concentration → insufficient freezing point, posing a risk of pipe freezing in northern winters; too high a concentration → increased viscosity, leading to higher pump energy consumption and reduced heat transfer efficiency.

Drift sources:

Dilution due to system makeup water;
Local concentration increases as the evaporative section under high load preferentially removes water;
Slow oxidation and decomposition of ethylene glycol.

Recommendation: PS7400 tuning fork density meter (density accuracy ±0.001 g/cm³, convertible to concentration accuracy ±0.5%), installed in the main loop of the heat exchanger.

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