Product Overview
40% Propylene Glycol Inhibited is a technical grade aqueous glycol solution built for closed-loop heat transfer systems. At a 40% concentration in water, it delivers freeze protection and thermal stability for facilities that need reliable year-round fluid performance without the higher viscosity of more concentrated blends.
This inhibited formulation includes corrosion inhibitors designed to protect system metals — ferrous alloys, copper, brass, and solder joints — inside sealed piping and equipment. Facility engineers, HVAC contractors, and maintenance teams working with hydronic boilers, process chillers, and industrial cooling loops are the primary buyers.
Why This Concentration
A 40% propylene glycol blend sits in the middle of the concentration range, and that position is deliberate. It provides meaningful freeze depression for systems exposed to moderate winter temperatures while keeping viscosity and pumping costs lower than a 50% Propylene Glycol Inhibited or 100% Propylene Glycol Inhibited concentrate. For facilities in milder climates or systems where the fluid rarely sees sub-zero conditions, 40% often hits the operating sweet spot.
If your system operates in warmer regions or you need a lighter fluid for reduced pump load, consider 30% Propylene Glycol Inhibited. For harsher freeze environments, step up to the 50% blend. The trade-off is always the same: higher glycol concentration means more freeze protection but greater viscosity and slightly reduced heat transfer efficiency.
The inhibitor package is the other half of the equation. Uninhibited glycol in a sealed metal system will degrade over time, producing acidic byproducts that attack copper and steel. This inhibited formulation is intended for closed-loop service where long fluid life and metal compatibility matter.
Chemical Profile
40% Propylene Glycol Inhibited is supplied as a clear, colorless liquid. It has an odorless to mild character and a density of 1.02–1.04 g/cm³ — slightly heavier than water, consistent with a 40% glycol-in-water blend. The fluid is fully miscible with water, which allows field adjustment of concentration when needed. Propylene glycol carries the molecular formula C₃H₈O₂, a molecular weight of 76.09 g/mol, and is identified by CAS number 57-55-6.
Industrial Applications
The 40% inhibited blend serves a specific set of industrial fluid applications where low toxicity and corrosion protection run together.
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HVAC hydronic systems — Closed-loop heating and cooling circuits in commercial buildings, hospitals, and data centers use inhibited propylene glycol as the heat transfer fluid. The 40% concentration protects against freeze damage in rooftop piping and air handlers exposed to winter conditions.
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Industrial boilers and chillers — Process boilers and glycol chillers that cycle between heating and cooling loads rely on a stable transfer fluid. This blend circulates through shell-and-tube exchangers, plate exchangers, and jacketed vessels to move thermal energy efficiently.
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Antifreeze for non-toxic service — Where system leaks could contact potable water, food processing areas, or occupied spaces, propylene glycol is chosen over ethylene glycol for its lower toxicity profile. The inhibited 40% blend is a common specification for these environments.
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Industrial process cooling — Batch reactors, plastic mold temperature controllers, and laser cooling systems use glycol loops to hold tight temperature tolerances. The 40% blend provides freeze margin without over-thickening the fluid at operating temperature.
Handling & Storage
This product is not classified as hazardous under GHS based on available data. No GHS signal word or hazard pictogram applies.
Standard industrial hygiene practices still apply. Wear chemical-resistant gloves and safety goggles when handling to prevent skin and eye contact. In enclosed spaces or during transfer operations, ensure adequate ventilation to limit inhalation of any mist or vapor.
Store in sealed containers made of compatible materials — HDPE drums, stainless steel, or lined carbon steel. Keep containers in a cool, dry area away from direct sunlight and heat sources. Avoid contact with strong oxidizing agents, which can degrade the glycol and exhaust the corrosion inhibitor package. Partially filled containers should be resealed promptly; prolonged air exposure accelerates oxidation and shortens inhibitor life.
Hazmat & Shipping
40% Propylene Glycol Inhibited is not regulated as a hazardous material for transport. No UN number, hazard class, packing group, or proper shipping name is assigned to this product (per 49 CFR 172.101). It ships as a non-regulated commodity under DOT ground transportation rules.
Note that a non-hazardous DOT classification governs the regulatory status of the material itself. Individual carrier policies, surcharges, and routing decisions are set by the carrier and may vary.
Documentation
A Safety Data Sheet (SDS) in English ships with every order and is available on request before purchase. A Technical Data Sheet (TDS) is also available, detailing the product's physical and performance properties. For quality verification, a lot-specific Certificate of Analysis (COA) can be provided — request one at time of order if your receiving process requires incoming QC documentation.
Why Buy from Alliance Chemical
This product is available in pack sizes from single quarts up through 330-gallon totes, with SDS, TDS, and lot-specific COA documentation available for every order — a range that covers bench-scale evaluation through full production fill. Alliance Chemical has served over 50,000 customers since 1998, and every product page on this site is reviewed by Andre Taki, DOT Hazmat Specialist, to ensure shipping and handling guidance is accurate and governed by the applicable regulation.
