The “Food-Grade” Data Center Coolant Myth

How Prometheus Hyperscale is Using Manufacturing Purity Standards to Disguise Environmental Risks and Industrial Reality in Wyoming

May 30, 2026 WyoDataCenterFacts AI Tech Trends, Claim - Truth, Community Health, Environmental Impact Comments Off on The “Food-Grade” Data Center Coolant Myth
Photo: Castrol

CLAIM–TRUTH: “PG25 is Food‑Grade”

CLAIM

“We fill the system once with a food‑grade fluid called PG25.” & “Propylene Glycol is a food‑grade material found in cosmetics, food products, and medicines.” — Prometheus Hyperscale PR

TRUTH

Prometheus is using marketing language to imply that PG25 is harmless. It is not. And the phrasing they are using is scientifically misleading.

1. Prometheus has not identified the manufacturer of their PG25.

This matters. There are multiple PG25 formulations on the market, and:

  • Many PG25 coolants are not NSF‑HT1 compliant.

  • Many PG25 coolants contain industrial inhibitor packages not approved for any food‑contact category.

  • NSF‑HT1 certification is product‑specific, not generic.

Because Prometheus has not disclosed the manufacturer, the product name, the Safety Data Sheet (SDS), or the certification documentation, they cannot claim their PG25 is “food‑grade” in any meaningful or verifiable sense. If they cannot name the product, they cannot claim the certification.

2. NSF‑HT1 does NOT mean “safe to ingest” or “safe at scale.”

Some PG25 coolants used in data centers carry an NSF‑HT1 certification. Prometheus uses this to imply biological safety — but that is not what HT1 means.

HT1 is an incidental‑contact lubricant and heat-transfer standard, created for commercial food‑processing machinery. It means:

  • The base chemical was manufactured to a high‑purity standard.

  • The additives are allowed for trace, accidental contact (measured in parts-per-million).

  • The mixture contains no heavy‑metal contaminants.

It does not mean safe to drink, safe in ounces, safe in gallons, safe for humans, or safe for the environment.

An NSF purity level does not mean the chemicals themselves aren’t harmful to humans or the environment at scale. To drive the point home: there are industrial machinery greases that are “food‑grade” NSF compliant — but you wouldn’t eat them. NSF‑HT1 is a manufacturing‑purity label, not a biological‑safety label. Prometheus is deliberately blurring that line.

3. Food‑use propylene glycol is measured in milligrams — not ounces.

Prometheus keeps saying “propylene glycol is in food.” That is true — but only in tiny, milligram‑level quantities.

  • Flavored beverages: 10–50 mg

  • Baked goods: 50–200 mg

  • Typical daily dietary exposure: under 100 mg

Now compare that to real quantities:

  • 1 fluid ounce of PG = ~30,000 mg

  • 2 fluid ounces = ~60,000 mg

  • 8 fluid ounces = ~240,000 mg

Food exposure is measured in milligrams. Toxicity occurs when ingestion reaches ounces. Even pure, pharmaceutical‑grade PG becomes dangerous when consumed in large amounts because the liver cannot metabolize it fast enough, leading to lactic acid buildup and severe metabolic acidosis requiring hospital evaluation.

4. PG25 has no safe ingestion level.

This is the part Prometheus never mentions: There is no “safe dose” of PG25. Any ingestion of a formulated PG25 coolant is treated medically as a poisoning exposure because the mixture contains industrial additives with no safe exposure threshold.

PG25 is not pure PG. It is a coolant mixture containing corrosion inhibitors, buffers, stabilizers, and anti‑foam agents. None of these are approved for ingestion. None have human safety thresholds. None are “food‑grade.”

5. Purity ≠ Safety. A pure chemical can still be hazardous at hyperscale volumes.

Prometheus wants the public to believe that “pure” means “harmless.” But environmental science says the opposite.

A spill of 50,000 gallons of PG25 into Wyoming soil or waterways would cause a massive Biochemical Oxygen Demand (BOD) spike. Propylene glycol is rapidly consumed by aquatic bacteria, which:

  • Explode in population.

  • Violently strip dissolved oxygen from the water.

  • Suffocate fish and aquatic life.

  • Create dead zones and long‑term ecological damage.

This happens regardless of manufacturing purity. A pure chemical is still a highly toxic hazard at hyperscale volumes.

6. The Real Engineering Trap: Two Completely Different PG25 Worlds — and Prometheus Is Hiding Which One They’re Using

Every major coolant manufacturer produces two entirely different parallel tracks of propylene‑glycol‑based coolants:

Track 1 — The “Food‑Grade” Line (NSF‑HT1)

These are formulated with mild, food‑safe inhibitors such as Dipotassium phosphate, Potassium sorbate, and benign organic buffers. (Examples: Standard DOWFROST™, Arteco Zitrec™ FG).

These fluids are designed for incidental contact in commercial food‑processing plants. They are not designed for ingestion, they are not safe for environmental release, and they are not engineered for high‑temperature copper computing systems.

Track 2 — The Heavy Industrial Line (Non‑Food‑Grade)

These are formulated with aggressive, highly toxic corrosion inhibitors such as Tolyltriazole (TTA) and Benzotriazole (BTA) (Yellow metal passivators), Nitrites, and Industrial OAT packages. (Examples: DOWFROST™ HD, Dober ThermoSafe™ PG25).

These are explicitly NOT food‑grade. They are classified as industrial chemicals with high aquatic toxicity.

Why This Is a Massive Problem for Prometheus

Data‑center Direct Liquid Cooling (DLC) cold plates are made almost entirely of copper, aluminum, and brass. These metals are extremely vulnerable to corrosion under thermal load.

Here’s the engineering reality: Food‑grade inhibitors do a terrible job protecting raw copper and aluminum. They were never designed for high-density direct-to-chip heat fluxes, high‑velocity microchannel fluid flow, galvanic couples between copper and aluminum, or multi‑year continuous operation without heavy maintenance.

Using a food‑grade PG25 in a hyperscale AI cooling loop risks rapid galvanic corrosion, copper pitting, and aluminum dissolution. In fact, if the pH drifts, the phosphate buffers in food-grade coolants can actually attack the aluminum components, leading to catastrophic server‑rack failure.

This is why hyperscale operators overwhelmingly prefer the industrial, non‑food‑grade track. The highly toxic azole inhibitors (like tolyltriazole) are strictly required to form a protective film on copper and prevent the cooling loop from dissolving from the inside out.

In other words:

If Prometheus really is using a food‑grade PG25, they are sacrificing the lifespan of their multi-million dollar hardware just to secure a PR talking point. And if they are using the industry-standard azole inhibitors to protect their copper… then they are lying to the public.

Sources:

1. The “Food-Grade” Loophole (NSF & FDA)

  • NSF International – Nonfood Compounds Registration (HT1 Classification) Defines the HT1 designation as strictly for “incidental contact” in food processing environments, explicitly not an approval for direct consumption or large-scale environmental release. (Source: NSF White Book™)

  • FDA – GRAS Status of Propylene Glycol Defines propylene glycol as “Generally Recognized As Safe” (GRAS) only in microscopic, strictly controlled food‑use quantities, not bulk industrial volumes. (Source: 21 CFR § 184.1666)

2. Human Toxicity at Volume

  • ATSDR (Agency for Toxic Substances and Disease Registry) – Propylene Glycol Documents the medical reality of ingestion, confirming that consuming large amounts causes lactic acidosis, central nervous system depression, and requires medical intervention. (Source: CDC / ATSDR Toxicological Profile for Propylene Glycol)

3. Environmental Impact at Scale (BOD)

  • EPA – Biochemical Oxygen Demand (BOD) of Glycols Verifies that large-scale propylene glycol spills are an acute environmental hazard. Aquatic bacteria rapidly consume the glycol, severely depleting dissolved oxygen and suffocating aquatic ecosystems. (Source: EPA Water Quality & Industrial Discharge Guidelines)

4. The Engineering Reality (Data Center Standards)

  • ASHRAE TC 9.9 – Liquid Cooling Guidelines for Datacom Equipment The definitive engineering standard for data centers. Explains why raw PG/water cannot be used and details the severe corrosion risks to copper and aluminum cold plates, requiring complex chemical inhibitor packages. (Source: ASHRAE Technical Committees)

  • Open Compute Project (OCP) – Advanced Cooling Solutions Hardware consortium standards specifying industrial PG‑based coolants and the required chemical passivators for direct-to-chip cooling loops. (Source: Open Compute Project Wiki)

5. Industrial PG25 Coolant Specifications & SDS Data

  • DOWFROST™ vs. DOWFROST™ HD Technical Data Dow Chemical’s documentation proving the existence of two distinct tracks: the food-safe version (DOWFROST) and the heavy-duty industrial version (HD) which contains toxic corrosion inhibitors. (Source: Dow Chemical Heat Transfer Fluids)

  • Hyperscale Coolant SDS (Safety Data Sheets) Safety data for standard data center PG25 coolants (e.g., Castrol ON, Dober ThermoSafe, Solutherm OAT). All classify the formulated fluids as industrial chemicals requiring HazMat spill protocols, with no safe human ingestion level.

Wyoming Data Center Facts | Photo: Castrol

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