Twenty degrees Baumé is a hydrometer reading

The record disagrees with itself, and that is the lesson

Baumé is a hydrometer scale: a float reading, converted to a density, converted in turn to a concentration through a table. The aggregated public record for hydrogen chloride carries that conversion twice, and the two entries do not agree. One reads: “Grades: United States Pharmacopeia (35-38%); NF dilution (10%); technical (usually 18, 20, 22, 23 deg Be /baume/, corresponding to approx 28, 31, 35, 37% hydrogen chloride), FCC.” Another reads: “Available commercially as a 31% w/w (22 deg Baume, d: 1.16 kg/L) or 35% w/w (22 deg Baume, d: 1.18 kg/L) solution in water.” The first puts 20 °Bé at about 31 percent and 22 °Bé at about 35. The second assigns 22 °Bé to 31 percent and to 35 percent in the same sentence, at two different densities.

Neither entry is a measurement of a supplied lot, and this guide does not adjudicate between them. The point is the one a purchase document has to act on: a Baumé degree is not a concentration, it is a reading that becomes a concentration only through a stated table at a stated temperature, and the commercial usage is loose enough that a widely aggregated record contradicts itself. Write the weight percent, the basis, the reference temperature and the method on the order, and treat the Baumé figure as the trade shorthand it is. The same record does supply properly conditioned density data — 1.15 at 29.57 percent and 1.20 at 39.11 percent, both at 15 °C referred to water at 4 °C — which is what a conditioned number looks like.

The exposure card is written for the gas

The NIOSH Pocket Guide card most people reach for is “Hydrogen chloride,” CAS 7647-01-0, and it describes “a colorless to slightly yellow gas with a pungent, irritating odor,” shipped as a liquefied compressed gas, with a molecular weight of 36.5 and a boiling point of −121 °F. Its ceiling limit of 5 ppm, 7 mg/m³, is a limit on airborne hydrogen chloride, matched by OSHA in Table Z-1. The card notes the material is often used in an aqueous solution and gives DOT identifiers for both — 1050 for the anhydrous gas, 1789 for the solution — but the properties on it are the gas’s. Reading a boiling point of −121 °F off that card and applying it to a drum of 31 percent solution is the ordinary error.

What the card does supply for a purchase record is the materials question. It lists incompatibilities as “hydroxides, amines, alkalis, copper, brass, zinc,” with the note that hydrochloric acid “is highly corrosive to most metals.” Those belong in the wetted-materials field alongside the pump, hose, gasket and vent arrangement. This is also where an inhibited acid has to be handled carefully: an inhibitor is a formulation additive, and a statement that an acid is inhibited is a claim about evidence — which formulation, at what concentration, against which alloy, at what temperature, for how long, and measured how. This library treats that question at length in its HVAC and geothermal collection, under “A corrosion-inhibitor claim is a claim about evidence,” and does not repeat it. Nothing here states that any Alliance product is inhibited, or is suitable for contact with any specific metallurgy.

Three assays at one density

The sulfuric acid record makes the same point from the other direction. Its grade table reads: “Commercial 60 degrees Be: (density 1.71, 77.7% sulfuric acid); 66 degrees Be (density 1.84, 93.2% sulfuric acid); 98% (density 1.84); 99% (density 1.84); 100% (density 1.84), depending on supplier; reagent ACS, CP.” Three different assays are quoted at the same density, and the table itself says the difference is “depending on supplier.” At the concentrated end of this scale density stops resolving concentration, so a hydrometer reading cannot settle an argument about assay and a titration has to.

Two further entries matter for a diluted product. The impurity figures the record gives — “Non-volatiles, 0.02-0.03 ppm; SO2, 40-80 ppm; iron, 50-100 ppm; nitrate, 5-20 ppm” — are attached specifically to “technical grade, industry type, 66 deg Baume,” which is to say they describe one designation and do not transfer to a dilute solution. And on materials the record is explicit that concentration inverts the answer: “concentrated acid is non-corrosive to lead and mild steel but dilute acid attacks most metals,” with corrosiveness “highly dependent on concentration, temperature, acid velocity, and acid impurities.” A tank and transfer arrangement chosen for concentrated acid is not thereby justified for a dilute one. The same record carries “Battery acid” and “Sulphuric acid 37% techn. (battery acid, accumul. acid)” among its depositor-supplied synonyms, and separately reports a specific gravity of 1.84 explicitly qualified as “(96-98% acid)” — a figure that says nothing about a 37 percent solution. A synonym contributed by a depositor and a property measured under stated conditions are not the same class of evidence, and a record that holds both side by side will happily let you read one as the other.

Both of these acids are listed chemicals

A fact that surprises buyers and belongs on a purchasing checklist: hydrochloric acid and sulfuric acid are both List II chemicals under the Drug Enforcement Administration’s rules. 21 CFR 1310.02(b) names them at paragraphs (8) and (9) — “Hydrochloric acid (including anhydrous hydrogen chloride)” and “Sulfuric acid” — alongside acetone, toluene, methyl ethyl ketone, acetic anhydride and potassium permanganate, several of which also sit in this catalog. Listing brings recordkeeping and reporting consequences for a regulated person, and § 1310.04(b) requires records for a List II chemical transaction to be kept for two years after the date of the transaction.

This is not a hazard classification and it does not appear on a safety data sheet as one. It is a separate regulatory identity attaching to the same drum, and a purchasing team that has mapped a material’s hazard class, its transport classification and its exposure limits has still not necessarily mapped this. Nothing here is legal advice, and whether any particular party or transaction is covered is a determination for the reader and their counsel.

And the listing is narrower than the list suggests

Read only § 1310.02 and you would draw the wrong conclusion, which is why the companion section matters. 21 CFR 1310.08(a) excludes from the definition of a regulated transaction “domestic and import transactions of hydrochloric and sulfuric acids but not including anhydrous hydrogen chloride.” Paragraph (b) then excludes exports, transshipments and international transactions of the same two acids “except for exports, transshipments and international transactions to” fourteen named countries: Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, French Guiana, Guyana, Panama, Paraguay, Peru, Suriname, Uruguay and Venezuela. For those destinations § 1310.04(f)(2)(iv) sets a threshold of 50 gallons for each acid, with 27 kilograms for anhydrous hydrogen chloride.

So the listing is real, the domestic exclusion is real, the geographic carve-out from the exclusion is real, and the anhydrous gas is treated differently from the solution throughout. That is four distinctions in two short sections, and each of them is the kind of detail that a summary loses. The general habit is the transferable part: when a rule is cited at you, read the section that states the exclusions before acting on the section that states the coverage. Again, nothing here is legal advice.

Where the discharge boundary is drawn

40 CFR part 435 is the effluent-guideline category for oil and gas extraction, and it is worth knowing what it does and does not reach. It divides the industry by location and production rather than by chemistry: subpart A offshore, applying to facilities “engaged in field exploration, drilling, well production, and well treatment” seaward of the inner boundary of the territorial seas; subpart C onshore; subpart D coastal; subpart E, headed the agricultural and wildlife water use subcategory but described in its own applicability section as the beneficial use subcategory, which reaches onshore facilities west of the 98th meridian whose produced water “is of good enough quality to be used for wildlife or livestock watering or other agricultural uses and that the produced water is actually put to such use during periods of discharge”; subpart F the stripper subcategory, for onshore facilities producing ten barrels per well per calendar day or less; and subpart H, coalbed methane, which is [Reserved] — the part is not uniformly complete, and reading it means checking whether the subcategory you land in has any text in it.

The onshore limit at § 435.32 is the shortest sentence in the part and the most consequential: best practicable control technology is “no discharge of waste water pollutants into navigable waters from any source associated with production, field exploration, drilling, well completion, or well treatment,” naming produced water, drilling muds, drill cuttings and produced sand. Subpart G then closes the obvious workaround, stating at § 435.70(a) that the subpart exists to prevent facilities “from circumventing the effluent limitations guidelines and standards applicable to those facilities by moving effluent produced in one subcategory to another subcategory for disposal under less stringent requirements.”

Two things follow for a purchase record. Which subcategory governs a facility is a written determination somebody owns, and the obligation it creates runs to the facility and its permit — not to the supplier of any chemical, and not to anything printed on a drum. And the part shows again how a federal rule handles a private standard: § 435.11(i) defines diesel oil by reference to “the grade of distillate fuel oil, as specified in the American Society for Testing and Materials Standard Specification for Diesel Fuel Oils D975-91,” incorporated by reference — a specific edition, from 1991, that a reader must obtain from the publisher or inspect at a records location. That is the same pattern as ASTM D3699 in the kerosene guide: the rule names the document and pins the edition, and the numbers themselves are somewhere you have to go and get.

• Is the concentration written as weight percent with a basis and a reference temperature, or only as a Baumé degree?
• Which attributes does your specification control — iron, chloride, sulfate, free acid, residue — each with a method, units and a reporting limit?
• Which alloys, elastomers and gasket materials contact the acid at the delivered concentration and temperature, and who approved them?
• Who owns the permit, the discharge determination and the exposure assessment for this operation?

What a supplier can settle, and what it cannot

What a supplier can put in writing is the identity of the material, the concentration on a stated basis, the attributes it measured with the methods it used, the packaging and the lot documents. Alliance sends a Certificate of Analysis when a customer asks, at no charge; name in the purchase order which document is meant, because a sample certificate is not a lot certificate. A nominal concentration shared between two products does not establish interchangeability, and an industry listing is not an application approval.

What a supplier cannot settle is everything downstream of the drum: the treatment design, the rate, the sequence, the metallurgy of a specific system, the discharge determination and the exposure assessment. This guide supplies none of them, states no dose or application rate, and does not say that any Alliance product is suitable, approved or recommended for well service, equipment cleaning or any other use. It is source-based editorial guidance, no original testing was performed for it, and independent specialist review is pending.

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.