Product Overview
Propylene Glycol Inhibited ACS Grade is 1,2-propanediol (CAS 57-55-6, formula C₃H₈O₂) formulated with a corrosion inhibitor package for closed-loop heat transfer systems and industrial fluid circuits. The ACS Grade designation marks the procurement tier that analytical laboratories and process-critical buyers typically specify when purity requirements go beyond a standard technical grade. "Inhibited" means the glycol carries additives that protect ferrous and non-ferrous metals in cooling and heating loops — extending service life of pumps, heat exchangers, and piping without altering the base solvent's thermal or miscibility properties.
Alliance Chemical offers this product in sizes ranging from 1-quart bottles for bench-scale evaluation up through 330-gallon totes for full-system fills and production use.
Why This Grade
Buyers choosing this product are making two decisions at once: grade and formulation type.
The ACS Grade label tells a procurement team that this propylene glycol is sourced and labeled at the specification tier commonly requested for analytical work, quality-control reference preparations, and processes where the purity of the glycol matters to the outcome. Facilities running HPLC separations, preparing reference solutions, or formulating solvent blends where baseline contaminants could interfere will look for this designation on the certificate of analysis.
The inhibited formulation adds a corrosion-protection package to the neat glycol. In heat transfer and cooling loops, uninhibited glycol eventually turns acidic and attacks metal surfaces — gaskets pit, tube walls thin, sediment fouls exchangers. The inhibitor chemistry buffers pH and passivates metal, which is why operators spec an inhibited fluid for any closed-loop system they intend to run season after season. If your application is strictly bench-scale analytical work — where the glycol never contacts metal piping at temperature — an uninhibited grade may be appropriate. If it touches a chiller, boiler loop, or jacketed reactor, inhibited is the standard call.
Chemical Profile
Propylene glycol inhibited ACS Grade presents as a thick, colorless, practically odorless liquid (molecular weight 76.09 g/mol). It is fully miscible with water — solubility is reported at 100 mg/mL or greater at 70 °F — making dilution straightforward for heat transfer fills and solvent preparations. Density sits at 1.04 at 68 °F, slightly denser than water, so the fluid will settle below a water layer if left unmixed. Vapor pressure is low: 0.08 mmHg at 68 °F, rising to 0.13 mmHg at 77 °F, which means negligible evaporative loss under normal ambient storage and minimal vapor exposure during open handling. The combination of water miscibility, low volatility, and near-zero odor is what makes propylene glycol a preferred carrier fluid and solvent across industries that need a non-volatile, pumpable liquid.
Industrial Applications
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Heat transfer fluid in cooling and heating systems. Propylene glycol is the standard fill for closed-loop chillers, HVAC glycol loops, jacketed vessels, and solar thermal circuits. The inhibited formulation protects system metals from corrosion, and the glycol's freeze-point depression keeps lines from bursting in cold climates. Operators dilute to the ratio their system's minimum design temperature requires — typically 30–60 % glycol by volume — and top off seasonally.
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Analytical solvent and HPLC mobile phase component. In reversed-phase liquid chromatography, propylene glycol serves as a mobile-phase modifier or sample solvent. The ACS Grade designation is what analysts look for when the method demands a glycol free of interfering contaminants at the detection levels their instrument runs.
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Carrier fluid in hydraulic and industrial systems. Low volatility and thermal stability make propylene glycol a practical carrier fluid for hydraulic circuits, quench baths, and heat-sink reservoirs where water alone would corrode or evaporate.
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Solvent in pharmaceutical and process formulations. Propylene glycol dissolves a broad range of organic compounds while remaining water-miscible, which makes it useful as a co-solvent or vehicle in compounding and process chemistry.
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Humectant and moisture-retention agent. In industrial processes where controlled moisture levels matter — coatings, textile treatments, adhesive formulations — propylene glycol's hygroscopic nature holds water in the matrix and slows drying.
Handling & Storage
Propylene glycol inhibited ACS Grade is not classified as hazardous under GHS based on available data (per the product's GHS classification). No GHS signal word, pictogram, or hazard statement applies. That said, standard industrial hygiene still governs the workspace:
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PPE: Wear chemical-splash safety goggles and nitrile or compatible chemical-resistant gloves during transfer and handling. Prolonged or repeated skin contact can cause mild irritation and drying.
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Ventilation: Vapor pressure is very low (0.08 mmHg at 68 °F), so vapor accumulation under normal conditions is minimal. In enclosed or heated spaces — for example, when charging a hot loop — provide general mechanical ventilation as a precaution.
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Incompatibilities: Keep away from strong oxidizing agents. Propylene glycol can react with oxidizers under heat or confinement.
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Storage: Store in a cool, dry area away from direct sunlight. Keep containers sealed when not in use. HDPE drums, IBC totes, and glass bottles are all compatible — avoid containers that may leach contaminants into the glycol.
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Stability: The inhibitor package maintains its protective chemistry in sealed storage. Once the container is opened and the fluid is in service, monitor pH periodically — inhibitor depletion lowers pH and reduces corrosion protection over time.
Hazmat & Shipping
Propylene glycol is not regulated as a hazardous material for transport under DOT (per 49 CFR 172.101). It carries no UN number, no DOT hazard class, no packing group, and no proper shipping name. Shipments move as non-regulated freight. This classification applies to the product itself — carrier-specific policies, routing restrictions, and surcharges are determined by the carrier and are outside the scope of the DOT classification.
Shipping and handling guidance on this page has been reviewed by Andre Taki, DOT Hazmat Specialist.
Documentation
A Safety Data Sheet (SDS) ships with every order and is available in English, Spanish, French, and Japanese. A lot-specific Certificate of Analysis (COA) is available on request — the COA documents the specific production lot shipped to your facility. A Technical Data Sheet (TDS) with product specifications is also available for procurement and engineering review.
Why Buy from Alliance Chemical
This product ships as non-regulated freight with full documentation — SDS, COA, and TDS — from a single distributor stocking quart bottles through 330-gallon totes, so a QC lab ordering a single quart and a mechanical contractor filling a 275-gallon chiller loop both order from the same source. Alliance Chemical has operated from our Taylor, Texas warehouse since 1998 and has served more than 50,000 customers across industrial, analytical, and process markets.
