Coolants for AI and data center cooling

Inhibited propylene and ethylene glycol premixes for direct-to-chip loops and CDUs, concentrates, deionized water, and the treatment chemicals cooling towers run on.

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Every size listed is priced and sold online, with no minimum. Quotes are for multi-unit, bulk and recurring supply. Or call 512-365-6838.

Aisle between rows of server racks

Photo: İsmail Enes Ayhan on Unsplash

Where the chemistry goes

Heat leaves a GPU through a cold plate, crosses a coolant distribution unit and ends up in a cooling tower or dry cooler. Each loop wants a different fluid.

  1. Step 1 Direct-to-chip loop

    Liquid-cooled rack with manifold, cut away

    The technology loop runs through cold plates on the processors. Propylene glycol premixes with an OAT inhibitor package are the common choice. Top up with the same premix, and use deionized water to flush.

  2. Step 2 Coolant distribution unit

    Heat exchanger in a CDU, cut away

    The CDU passes heat from the technology loop to facility water. Ethylene glycol carries heat better than propylene glycol and is used where its toxicity is acceptable.

  3. Step 3 Cooling tower

    Cooling tower with fill and basin, cut away

    Facility water is cooled by evaporation, which concentrates minerals. Towers run acid to control alkalinity and scale, an oxidant, and periodic descaling.

  4. Step 4 Flush and fill

    Fill cart tank, cut away

    New loops are flushed before the first fill. Concentrates let you mix to your own ratio with deionized water.

Technical notes

Reference notes for specifying coolant for direct-to-chip, CDU and facility loops, from the equipment requirement down to the drum or tote you receive.

Key specifications

Specification Why it matters
Fluid identity and concentration Name the exact formulation, the inhibitor type (OAT, HOAT or other) and whether the ratio is by volume or by weight. Two products sold as 25% propylene glycol are not interchangeable unless the formulations match.
Thermal and hydraulic properties Density, specific heat and viscosity change with glycol concentration and temperature. The heat balance and pump sizing depend on the values for the exact fluid at operating temperature.
Freeze and burst protection Freeze point and burst point are different numbers. Indoor technology loops often need little freeze protection, while dry coolers and outdoor piping set the concentration.
Dilution and make-up water quality Chloride, sulfate and hardness cause corrosion and deposits in cold plates. Use the water quality the fluid and equipment makers specify, usually deionized water.
Wetted materials and documents List the copper, aluminum, stainless steel and elastomers in the loop, then compare them with the fluid's compatibility data. Keep the current SDS, TDS and the COA for the lot received on file.

Start with your cooling circuit

Buying data center coolant starts with the equipment requirement, not the glycol name. A liquid-cooled AI rack usually has two loops. The technology cooling system runs through cold plates on the GPUs and CPUs and returns to a coolant distribution unit (CDU). The facility water system carries that heat from the CDU to a cooling tower, chiller or dry cooler.

Each loop has its own fluid specification. Cold-plate loops commonly run PG25, a 25% propylene glycol with an OAT inhibitor package, or another premix the server maker approves. Facility loops may run ethylene glycol where its toxicity is acceptable, or treated water where freezing is not a risk. ASHRAE TC 9.9 liquid cooling classes set facility water supply temperatures.

Record the equipment model, manual revision, wetted materials and existing fill before you compare products. Treat immersion as a separate question: a low-conductivity water-based coolant is not a dielectric immersion fluid.

Grade is one part of the requirement

Technical, ACS, USP and semiconductor grade describe the purity of the base glycol. None of them tells you whether a corrosion inhibitor is present, which package it is, or whether a server maker has approved the fluid.

A high-purity uninhibited glycol still turns acidic as it ages and attacks copper and aluminum. An inhibited premix such as inhibited propylene glycol 25/75 with OAT inhibitor is a different product from technical-grade propylene glycol diluted on site, even at the same percentage. Compare the full formulation and the product documents with the approved requirement, and do not substitute on a shared chemical name or nominal concentration. See the data center cooling collection for the inhibited premixes and concentrates.

Safety and compliance

Review the current SDS for the exact formulation and follow the site's handling and spill procedures. OSHA's Hazard Communication Standard (29 CFR 1910.1200) requires that SDS be available to the technicians who fill and service the loops.

Ethylene glycol is an OSHA hazardous chemical, so a site holding 10,000 lb or more on hand, about four full totes of concentrate, files EPCRA Tier II inventory reports. A release of 5,000 lb or more of ethylene glycol is reportable to the National Response Center under CERCLA. Spent glycol is not a drain-disposal product; many states allow recycling, and contaminated fluid may need waste testing. Confirm storage, reporting and disposal rules for your location with the responsible environmental team. Find product documents in the SDS library.

Common purchasing mistakes

  • Treating equal percentages as the same fluid. OAT and silicate-based inhibitor packages are not designed to be mixed. Top up with the formulation already in the loop.
  • Misreading the ratio. A 50/50 by volume and a 50/50 by weight are different mixtures with different freeze points.
  • Topping up with tap water. Minerals and chloride cause deposits and corrosion in narrow cold-plate channels. Use the same premix, or concentrate with deionized water.
  • Skipping fluid testing. Track concentration, pH and reserve alkalinity (ASTM D1121) so inhibitor depletion shows up before corrosion does.
  • No release owner. Decide who approves a delivered lot before it goes into a live loop.

Shipped from Taylor, Texas

Most in-stock orders leave in one to two business days. Parcel or freight depends on what is in the box, not on who is buying, and every size listed is sold online.

UPS Ground Bottles, jugs and up to three pails
LTL freight Four or more pails, drums and totes, by liftgate truck on a pallet
  • UPS
  • ABF Freight
  • FedEx Freight
  • R+L Carriers
  • Saia
  • Southeastern Freight Lines
  • XPO

The carrier's hazmat fee is passed through at cost. See the shipping guide for how orders are packed and rated.

Paperwork for your file

Safety data sheets are public. A certificate of analysis for the lot you receive is free on request.

Replacing a branded glycol?

Many brands name their premixes by percent glycol by volume or by burst temperature. We match on freeze point and show both sides of the comparison.

Questions buyers ask

Propylene glycol or ethylene glycol?

Ethylene glycol transfers heat better and is less viscous. Propylene glycol is far less toxic, which is why it is common in occupied buildings and in loops that run near people. Follow the equipment maker's fluid specification.

Why an inhibited premix instead of glycol and water?

Plain glycol becomes acidic as it ages and attacks copper, steel and aluminum. The inhibitor package protects the metals in the loop, and the premix is made with deionized water at a known ratio.

Can I top up a loop with tap water?

No. Chloride, hardness and other minerals in tap water cause corrosion and deposits on cold plates. Top up with the same premix, or with concentrate and deionized water mixed to the loop's ratio.

How do I check glycol concentration in the field?

A glycol refractometer gives a quick reading; have the loop tested for inhibitor level and pH as well at least once a year.

Can I buy totes on a schedule?

Yes. Single totes are sold online. For several sites or deliveries on a schedule, request a quote with your volumes and delivery points.

What freeze protection does a glycol premix give?

It depends on the glycol and the concentration. A 50% ethylene glycol by volume freezes near -34°F (-37°C), a 30% mix near +4°F (-16°C), and propylene glycol gives somewhat less protection at the same percentage. Check the freeze-point table for the exact product.

Is a 50/50 ratio by volume or by weight?

Coolant ratios are usually stated by volume, but some products state them by weight. Check the product's TDS, because the same label by weight gives a different concentration and freeze point.

What if my coolant's electrical conductivity is too high?

Compare the reading with the limit the equipment maker sets for that fluid. Inhibited coolants conduct electricity because of their inhibitor salts, so conductivity is not a leak-safety margin, and a rising reading can point to contamination or the wrong top-up water.

Do I need semiconductor-grade ethylene glycol?

Only if your equipment specification calls for it. A semiconductor grade describes the purity of the glycol, not an inhibitor package or approval for a cooling loop, and it does not make a fluid suitable for immersion cooling.

How do I get a certificate of analysis?

Ask for it with the product and lot number and we send the COA for the lot you received, free of charge. Safety data sheets for every product are in the SDS library.

Order today, or talk it through first

Every size listed on this page is priced and sold online. For drums and totes on a schedule, several delivery points or net 30 terms, send us your volumes and we will quote the product and the freight.

Shop data center coolantsRequest a bulk quote
Call sales 512-365-6838

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