What “K-1” fixes, and where that number actually lives

The definition points at a document you have to buy

The most precise federal definition of kerosene is in the excise-tax regulations, and it is worth reading in full because of where it sends you. 26 CFR 48.4081-1(b): “Kerosene means any liquid that meets the specifications for kerosene or would meet those specifications but for the presence in the liquid of a dye of the type described in § 48.4082-1(b). A liquid meets the specifications for kerosene if it is one of the two grades of kerosene (No. 1-K and No. 2-K) covered by ASTM specification D 3699, or kerosene-type jet fuel covered by ASTM specification D 1655 or military specification MIL-DTL-5624T (Grade JP-5) or MIL-DTL-83133E (Grade JP-8).”

So the two grades exist, they are named in federal law, and every attribute that separates them — the sulfur limit above all — lives in ASTM D3699, which is sold by ASTM International. Requested on September 12, 2026, the publisher’s page for it returned 403 to an unauthenticated client. It was not read for this guide, no limit from it is reproduced here, and this guide states no sulfur figure, flash point or Saybolt colour for either grade. If a purchase turns on K-1 rather than K-2, obtain the edition your specification invokes and cite its clauses by number; a buyer and a seller who have each never opened the document are agreeing to a set of limits neither of them can quote.

The same paragraph also defines an excluded liquid, which is a liquid that “contains less than four percent normal paraffins” or has a distillation range of 125 °F or less, a sulfur content of 10 ppm or less, and a minimum color of +27 Saybolt. A liquid can look like kerosene, sit next to it on a rack, and fall outside the definition on any one of those. Precision about what a material is is not pedantry here; it is the difference between two regulatory identities.

The colour in the drum is a tax fact

Dyed kerosene is a common sight and it is routinely misread as a quality signal. 26 CFR 48.4082-1 is short and says exactly what the dye means: tax is not imposed on the removal, entry or sale of diesel fuel or kerosene where the person otherwise liable is a taxable fuel registrant, the terminal is an approved terminal, and the fuel satisfies the dyeing requirement. That requirement is met only if the fuel contains “the dye Solvent Red 164 (and no other dye) at a concentration spectrally equivalent to at least 3.9 pounds of the solid dye standard Solvent Red 26 per thousand barrels of diesel fuel or kerosene,” or a dye of a type and concentration the Commissioner has approved.

That is the entire content of the colour. It records a tax status and a permitted use; it carries no information about sulfur, flash point, distillation, water and sediment, or anything else a specification controls. Undyed material is not therefore cleaner, and dyed material is not therefore dirtier. Neither is a substitute for the attribute limits, and a receiving record that notes “clear” or “red” has recorded a tax category rather than a property.

Kerosene is a designation somebody applied to a batch

EPA’s fuels rule treats the word as a label with a procedure behind it. 40 CFR 1090.80 defines kerosene as “any No. 1 distillate fuel that is used, intended for use, or made available for use as kerosene,” and distillate fuel as diesel and other petroleum fuels with a T90 temperature below 700 °F — a definition anchored to a distillation result, not a composition. § 1090.1015(a)(1) then requires a manufacturer to “accurately and clearly designate each batch” as at least one of nine listed types, kerosene among them, and § 1090.1100 requires that designation to travel on the product transfer document at each change of custody. The designation is a record with an owner, and it is the thing to ask for.

Two consequences are easy to get backwards. First, § 1090.1015(a)(3) allows a batch certified and designated as ULSD to also be designated kerosene “if it is also suitable for such use,” so a drum can honestly carry both labels — which means the label alone does not tell you which standard it was certified against. Second, and more often assumed wrongly: § 1090.315 states that kerosene “must not be sold for use in motor vehicles or nonroad equipment” and is “not subject to the ULSD standards in § 1090.305 unless it is also designated as ULSD.” The 15 ppm maximum sulfur content at § 1090.305(b) is a standard for diesel fuel. It is not a federal limit on kerosene, and a specification that needs a sulfur ceiling has to state one itself, with a method and a reporting limit.

What the material is, reported as ranges

The NIOSH Pocket Guide card for kerosene, CAS 8008-20-6, describes it as “a refined petroleum solvent (predominantly C9-C16), which typically is 25% normal paraffins, 11% branched paraffins, 30% monocycloparaffins, 12% dicycloparaffins, 1% tricycloparaffins, 16% mononuclear aromatics & 5% dinuclear aromatics.” Note the word typically, and note that the card gives boiling point as 347-617 °F, flash point as 100-162 °F, molecular weight as “170 (approx)” and specific gravity as 0.81 without a stated reference temperature. Those are the honest shape of the data for a distillation cut.

The flash-point range is the one with a purchasing consequence, because it spans a boundary. Under 29 CFR 1910.106(a)(19), a flammable liquid Category 3 runs to a flash point at or below 140 °F and Category 4 above 140 °F, so two lots of the same product, each legitimately kerosene, can classify differently. The classification of a delivery follows from the flash point of that delivery, measured by a stated method, and it is the employer’s determination and not a supplier’s. The general problem — that a petroleum cut has no single value for anything — is worked through in this library’s aerospace materials and cleanliness collection under “A petroleum cut is a range, not a substance,” and is not repeated here.

One product name in this collection contains the words “clean burning.” It is a name. This library makes no statement, and supports none, about the emissions, combustion behaviour or environmental characteristics of any fuel, and nothing here should be read as one.

The neighbouring cuts, and where their names collide

Mineral spirits sits beside kerosene in this collection and is the same kind of purchase. The NIOSH card for Stoddard solvent, CAS 8052-41-3, lists “Mineral spirits” among its synonyms and describes it as “a refined petroleum solvent with a flash point of 102-110 °F, boiling point of 309-396 °F, and containing >65% C10 or higher hydrocarbons,” with a physical description of “colorless liquid with a kerosene-like odor.” The two materials overlap in boiling range and in the way they are named, and they are not interchangeable on that account.

The exposure entries on that card show why a number needs its units and its basis. NIOSH gives a REL of 350 mg/m³ as a time-weighted average with a ceiling of 1800 mg/m³ over 15 minutes; the OSHA PEL on the same card is 500 ppm, given as 2900 mg/m³. Two authorities, two figures, and a substance whose molecular weight the card reports as “varies,” which is precisely why converting between ppm and mg/m³ here is not a clean arithmetic operation. None of these is a property of a purchased product: an exposure limit is an obligation on an employer, discharged by an assessment of the actual task, which no purchase document can supply.

• Which designation is being bought — K-1, K-2, a fuel-rule batch designation, or a producer’s cut — and which document defines it?
• What is the flash point of the material as delivered, by which method, and who made the classification determination that follows from it?
• Which attributes does your specification actually control, each with a limit, a method, units and a reporting limit?
• Does the transfer document carry the designation, and does it match what was ordered?

Ask for the document, and ask for the certificate

Alliance publishes the grade a product carries in its structured product data, and that record — not the marketing copy, and not the handle — is what a purchase document should quote. Where a grade is not stated for a product, the correct action is to ask rather than to infer one. A nominal designation or concentration does not establish interchangeability between products or between suppliers, and being merchandised under an oil and gas collection is merchandising: an industry listing is not an application approval.

Alliance sends a Certificate of Analysis when a customer asks, at no charge. Put the request in the purchase order and name what it must cover: the analytes, the methods, the units and the reporting limit for each. A typical or sample certificate describes what the product has generally looked like; a lot certificate reports results for the material being shipped, and the two are not the same document. This is source-based editorial guidance, no original testing was performed for it, and independent specialist review is pending. Nothing here states that a particular Alliance product is suitable, approved or recommended for any application.

Requirement → evidence → decision boundary

An editorial checklist for your review—not a table of product specifications.

Revision record

1.0 · September 12, 2026 — Source-based editorial edition. No original testing or product qualification is claimed.

For operators, service companies and their purchasing teams buying fuels, acids, glycols and light hydrocarbon cuts. This collection does not design or select a well treatment, set a dose, rate or blend, classify a delivered material, specify personal protective equipment, or make a discharge, permit or waste determination.