Industrial grade propylene glycol (PGI, ≥99.5%) for the U.S. market. Used in polyester resins, de-icing fluids, heat transfer systems, and coatings. Drums, totes, and bulk available with full documentation.
All shipments include a lot-specific certificate of analysis. Industrial grade is not suitable for food, pharmaceutical, or personal care applications.
| Chemical Name | Propylene Glycol |
|---|---|
| Grade | Industrial / Technical (PGI) |
| CAS Number | 57-55-6 |
| Molecular Formula | C₃H₈O₂ |
| Molecular Weight | 76.09 g/mol |
| EINECS Number | 200-338-0 |
| Assay (GC) | ≥99.5% |
|---|---|
| Specific Gravity (20/20°C) | 1.035–1.037 (8.64 lb/gal) |
| Water Content (KF) | ≤0.20% |
| Color (APHA) | ≤10 |
| Acidity (as acetic acid) | ≤0.002% |
| Chloride (Cl⁻) | ≤70 ppm |
| Sulfate (SO₄²⁻) | ≤60 ppm |
| Heavy Metals (as Pb) | ≤5 ppm |
| Iron (Fe) | ≤0.30 ppm |
| Residue on Ignition | ≤70 ppm |
| Appearance | Clear, colorless, viscous liquid |
|---|---|
| Boiling Point | 187–188°C (368–370°F) |
| Melting/Freeze Point | −59°C (−74°F) |
| Flash Point (Closed Cup) | 99°C (210°F) |
| Autoignition Temperature | 371°C (700°F) |
| Density @ 20°C | 1.036 g/cm³ (8.65 lb/gal) |
| Viscosity @ 25°C | ~40–48 mPa·s |
| Refractive Index (n20/D) | 1.431–1.434 |
| Vapor Pressure @ 20°C | ~0.08–0.13 mmHg |
| Water Miscibility | Complete (all ratios) |
| Odor | Practically odorless, faint sweet |
PGI serves as a critical building-block diol and functional fluid across multiple industrial sectors.
Propylene glycol reacts with maleic anhydride and isophthalic or orthophthalic acid via condensation polymerization to form unsaturated polyester resin (UPR), the matrix material for fiberglass-reinforced composites. PGI is the primary diol input — the single largest industrial use, consuming approximately 45% of total PGI volume globally. End products include wind turbine blades (the fastest-growing segment, driven by onshore and offshore wind expansion), marine hulls, corrosion-resistant FRP piping, construction panels, and automotive body panels. Industrial-grade PGI (≥99.5%) is specified for UPR because consistent hydroxyl number and low water content directly control resin molecular weight distribution and final cure characteristics; USP-grade purity is unnecessary and cost-prohibitive at production volumes.
Propylene glycol is the base fluid in Type I, II, III, and IV aircraft de-icing and anti-icing fluids per SAE AMS 1424 (Type I heated de-icing) and AMS 1428 (Type IV anti-icing). Heated 50% PG/water solution is applied to fuselage surfaces to remove existing ice; concentrated cold solutions applied to wing surfaces provide a holdover window before takeoff. PG is mandated over ethylene glycol at airports near sensitive watersheds due to its biodegradability and lower aquatic toxicity, with FAA and Transport Canada regulations increasingly specifying its use. Seasonal demand concentrates in Q4–Q1 (October through March).
Blended with corrosion inhibitors and water at 30–50% PG by volume, industrial-grade PG provides freeze protection to −30°C / −22°F (50% solution) for HVAC chillers, geothermal heat exchangers, solar thermal collectors, and food-plant glycol cooling loops. The growing electric vehicle market has created a significant new demand segment: lithium-ion battery thermal management systems require non-toxic coolant fluids that maintain cell temperatures between 15°C and 35°C — a specification well-matched to inhibited PG-based coolant. Unlike ethylene glycol, a PG spill in a food processing or EV manufacturing facility does not trigger environmental reporting thresholds.
PGI is a diol monomer in alkyd resin synthesis for architectural and industrial coatings. Esterification of PG with phthalic anhydride and drying oils (linseed, soybean, tall oil fatty acids) produces alkyd binders that control viscosity, gloss, and hardness in solvent-borne paints. PG-modified alkyds exhibit better moisture resistance and film flexibility than glycerol-modified analogues, because the secondary hydroxyl geometry reduces polymer crystallinity and improves film elongation at break — particularly important in exterior architectural coatings subject to thermal cycling.
Industrial grade is NOT food-safe or pharmaceutical-safe. For applications requiring FDA GRAS, USP-NF, or FCC compliance — including pharmaceutical excipients, food additives, cosmetics, and vaping liquids — use Propylene Glycol USP Grade instead.
Contact us for current pricing, lead times, and minimum order quantities.
Industrial grade propylene glycol (PGI, CAS 57-55-6) is a clear, colorless, viscous liquid with ≥99.5% purity meeting technical-grade specifications. It is NOT food-safe or pharmaceutical-safe. Used in polyester resin production, aircraft de-icing fluids, industrial heat transfer systems, coatings, and antifreeze where USP/food-grade purity is not required.
Industrial grade (≥99.5%) meets technical specifications for non-food applications. USP grade meets the United States Pharmacopeia monograph, is FDA GRAS (21 CFR 184.1666), and is approved for pharmaceutical, food, and cosmetic use. Industrial grade must NOT be used in food, drug, or personal care products — impurity limits for heavy metals, iron, and chloride are stricter in USP grade.
A 30% PG/water solution protects to approximately −13°C (9°F); a 50% solution protects to approximately −33°C (−27°F). PG-based antifreeze also provides heat transfer stability up to 175°C at the correct inhibitor package concentration.
CARMELSOLV™ supplies industrial grade PG in 55-gallon (208L) drums, 275–330 gallon IBC totes, bulk tanker quantities, and smaller R&D quantities. Contact us for current pricing and lead times.
Safety Data Sheet (SDS, GHS-formatted), Certificate of Analysis (COA, lot-specific), Technical Data Sheet (TDS), and TSCA compliance confirmation are available on request via the contact form.
Tell us your required volume and application. We'll respond with pricing, SDS, COA, and availability.