Product Overview
Propylene Glycol 40% – USP Grade (C3H8O2) is a pre-diluted aqueous solution of propylene glycol, CAS 57-55-6, offered at a fixed 40% concentration. It is a thick, practically odorless, colorless liquid that mixes freely with water. Buyers who order it from us fall into a few clear camps: pharmaceutical and formulation teams whose procurement specs call out the USP designation, food-processing and cosmetic formulators who use propylene glycol as a humectant and carrier solvent, and facilities crews who run glycol-water blends for freeze protection. Because the dilution is already done, it goes into a process line or a mixing tank without an on-site water-blending step.
Why This Concentration
A 40% solution is the middle of the glycol-water ladder. It carries enough propylene glycol for moderate freeze-point depression and for most humectant and solvent-carrier work, while staying less viscous and easier to pump and meter than richer blends. If your system sits in a colder environment or your process calls for more glycol per gallon, step up to Propylene Glycol 50% – USP Grade (C3H8O2); the 50% blend trades some pumpability for stronger freeze protection. The USP Grade descriptor matters at the purchase-order level: pharma, food, and cosmetic buyers commonly specify it so the paperwork trail matches their quality program, and every lot we ship is backed by a lot-specific Certificate of Analysis for buyers who need documented purity records. Pick the 40% when your process is already engineered around a pre-diluted feed and you would rather not blend on site.
Chemical Profile
Propylene Glycol 40% presents as a thick, colorless liquid with practically no odor, and it mixes with water in all the proportions a process operator is likely to encounter — published solubility is greater than or equal to 100 mg/mL at 70 °F. The 40% w/w aqueous solution has a density of 1.033 at 20 °C, so a gallon weighs noticeably more than a gallon of water; account for that when sizing drum handling equipment. Vapor pressure is low: 0.08 mmHg at 68 °F and 0.13 mmHg at 77 °F, which is why the liquid loses very little to evaporation in open transfer. The underlying molecule is propylene glycol, formula C3H8O2, molecular weight 76.09, CAS 57-55-6.
Industrial Applications
Propylene glycol earns its place in a plant because it is a water-miscible solvent and humectant with a low vapor pressure. In this 40% aqueous form it is used as:
-
Pharmaceutical formulation work — propylene glycol acts as a solvent and carrier for active ingredients; formulators in this space typically write the USP designation into their purchase specs, which is exactly what this listing supplies.
-
Humectant duty in food processing — the glycol binds moisture, which is how it holds texture in products that would otherwise dry out during storage.
-
Cosmetic and personal-care formulation — it functions as a humectant and a co-solvent that keeps other ingredients dissolved and the finished blend uniform.
-
Freeze protection and heat transfer — glycol-water blends depress the freezing point of a loop; a 40% blend gives moderate protection, and colder installations move up the concentration ladder.
In every one of these, the buyer's real question is concentration match: this is a 40% solution, so check whether your process sheet calls for further dilution or a stronger feed before you order.
Handling & Storage
This product carries no signal word — it is not classified as hazardous under GHS based on available data (per the product's GHS classification). That makes it one of the easier liquids in the warehouse to work with, but our crew still handles it like a chemical, not like water. Wear gloves and safety goggles during transfers, and ventilate enclosed transfer areas. Keep it away from strong oxidizing agents — that is the one incompatibility that matters for glycols. Store containers closed, in a cool, dry area out of direct sunlight; HDPE and glass are the container materials that hold up. The solution is stable in storage, and its low vapor pressure means sealed drums do not build meaningful headspace pressure under normal conditions.
Hazmat & Shipping
Propylene Glycol 40% is not regulated as a hazardous material for transport: it has no UN number, no assigned hazard class, no subsidiary hazard, no packing group, and no proper shipping name (per 49 CFR 172.101). For a receiving dock, that means the drums arrive as standard freight under DOT rules rather than under hazmat placarding requirements. We pack every container — quart bottles through 330-gallon totes — to survive freight handling, because a non-regulated liquid that leaks in transit is still a lost shipment.
Documentation
A Safety Data Sheet ships with every order, and we maintain the SDS in English, Spanish, French, and Japanese — useful if your EHS binder or an overseas affiliate needs a non-English copy. A Technical Data Sheet is available for engineers who want the product parameters before committing a PO. Each lot also carries a lot-specific Certificate of Analysis, which is the document your quality team will actually file against the USP Grade requirement on the purchase order. Request any of these before you buy if your vendor-qualification process requires document review first.
Why Buy from Alliance Chemical
We offer this product across the full packaging range a buyer actually needs — quarts and gallons for bench and pilot work, 5-gallon pails and 15- and 55-gallon drums for production, and 275- and 330-gallon totes for high-volume users — each backed by a lot-specific COA and a four-language SDS. Alliance Chemical has operated as an industrial chemical distributor since 1998, and more than 50,000 customers have bought from us. Every order ships from our Taylor, Texas warehouse by a team that packs regulated and non-regulated chemicals daily, and the shipping and handling guidance on this page is reviewed by Andre Taki, DOT Hazmat Specialist. If you need pricing on drum or tote quantities, request a quote today and include your target volume and delivery state.
