Hydrochloric acid, CAS 7647-01-0, is an aqueous solution of hydrogen chloride with a molecular weight of 36.46 g/mol. The commercial product is most commonly supplied at 20° Baumé (31.45 wt% HCl) and 22° Baumé (35.21 wt% HCl), while fuming reagent grades reach 36.5–38.0 wt%. The solution is a strong mineral acid with a pH below 1.0 at 1.0 mol/L and is aggressively corrosive to carbon steel, zinc, brass, and aluminum. Release of hydrogen chloride vapor increases sharply with temperature and concentration; therefore closed-loop vent return, packed scrubbers, and dry-disconnect transfer fittings are specified for tanker, IBC, and drum unloading.

How to Get an HCl Quotation: What We Need From You

Quotation turnaround for hydrochloric acid is controlled by the completeness of process data submitted with the inquiry. The minimum data set includes concentration basis, forecast volume, delivery frequency, packaging and unloading configuration, impurity limits, regulatory grade, and application conditions. Missing data forces the supplier to assume worst-case freight classification, a less favorable assay basis, or more expensive corrosion-resistant packaging, all of which alter unit pricing. The table below summarizes the data fields that historically have the largest impact on quotation accuracy.

Concentration basis is the most frequent source of pricing error. A request for “HCl 30%” can mean a hydroxide titration expressed as percent HCl or a density reading expressed as degrees Baumé. The same physical solution may be described as 31.45 wt%, 20° Baumé, or approximately 11.6 M depending on the laboratory report. ASTM E224-16 provides total acidity by sodium hydroxide titration, density and Baumé by hydrometer, and separate test methods for iron, arsenic, sulfate, sulfite, and non-volatile residue. The quotation must state whether the price is for dry hydrogen chloride equivalent or as-is solution weight. For annualized deliveries, a difference of 0.2 wt% between 31.45% and 31.65% changes delivered hydrogen chloride mass by approximately 0.64%, which is material for metal processing lines consuming 2,000 L/day.

Temperature correction is equally material at receiving terminals. Density and Baumé readings are temperature-dependent; when the hydrometer is read at 38 °C on a tank trailer that was certified at 15.6 °C, the apparent concentration is lower than the actual value if compensation is not applied. Metering systems without mass flow compensation can therefore under-dose or over-dose in continuous processes. Suppliers request the receiving tank temperature, the presence of a recirculation line, and the type of instrument—magnetic flowmeter, Coriolis meter, or positive-displacement pump—because these determine whether volumetric or mass basis pricing is appropriate.

Which Analytical Data Should Accompany a Quotation Request?

For reagent-grade material, the buyer should supply maximum allowable trace metal limits rather than stating “low metals” or “technical grade.” The ACS Reagent Hydrochloric Acid monograph sets an assay range of 36.5–38.0 wt%, residue after ignition at 5 mg/kg maximum, iron at 0.2 mg/kg maximum, arsenic at 0.01 mg/kg maximum, sulfate at 5 mg/kg maximum, sulfite at 1 mg/kg maximum, and free chlorine at 5 mg/kg maximum. ASTM E224-16 contains the standard wet chemical and instrumental procedures for verifying these parameters. For trace metals below 0.5 mg/kg, inductively coupled plasma–optical emission spectrometry is commonly required as a supplementary method because colorimetric and flame atomic absorption methods may lack the necessary detection limit.

If the quotation is for a food or drinking-water application, the grade designation must be matched to the Food Chemicals Codex monograph or NSF/ANSI 60. A general reagent-grade certificate of analysis is not a substitute for a food-grade certificate because the regulatory body, the certification scope, and the impurity reporting thresholds are different. Hydrochloric acid used as a pH control agent in food processing and as a cation resin regenerant in drinking water plants must be delivered with lot-specific documentation that links the shipment to the manufacturing date, sampling plan, and test results.

Reagent-Grade Trace Metal Limits and Packaging Constraints

Packaging selection is not a simple logistic detail. For laboratory quantities, HDPE carboys of 20 L are standard. For flexible production lines, 200 L drums and 1,000 L HDPE intermediate bulk containers reduce dead inventory but increase per-liter cost. For continuous pickling or water-treatment feed, tank trailers of 20,000 L require receiving tanks made of rubber-lined carbon steel, fiberglass-reinforced plastic, or polypropylene, with a scrubber or vent return line. UN 1789, Packing Group II, applies to aqueous hydrochloric acid shipments; 49 CFR 172.101 governs the hazard communication and packaging requirements. Quotations must confirm whether the receiving site has pressure pad or pump unload capability, dry-disconnect coupling, and secondary containment capacity for 110% of the largest container.

In hot-dip galvanizing and cold-rolling steel descaling, hydrochloric acid is preferred over sulfuric acid for faster oxide dissolution and less base-metal attack. Continuous pickling lines typically operate at 18–25 wt% HCl and 50–60 °C, with acid recovery systems that concentrate the spent pickle liquor and separate iron chloride by-products. The quotation for this application must include the expected iron tolerance in the fresh acid, the presence of acid recovery, and the rinse water flow, because iron carryover changes the effective free acid concentration and influences consumption economics.

When Anhydrous HCl Delivery Is Required Instead of Aqueous Acid

Certain processes require gaseous or liquefied hydrogen chloride rather than hydrochloric acid solution. Anhydrous hydrogen chloride is shipped as a liquefied gas under pressure and is classified as UN 1050, with hazard class 2.3 for toxic gas and class 8 for corrosive. The quotation path is different from aqueous acid because the shipment is governed by cylinder, tube trailer, or gas manifold specifications rather than liquid tank trailer logistics. Buyers should specify cylinder size, purity such as 99.99% or 99.999%, pressure regulator connection type, and whether the gas is for pharmaceutical hydrochlorination, silicon epitaxy, or organic synthesis. Anhydrous hydrogen chloride has a high vapor pressure at ambient temperature; published data for this specific configuration is limited, but a vapor-phase HCl stream requires a pressure-rated delivery system, leak detection, and a vent scrubber rated for the full cylinder pressure.

Hydrochloric acid must not be stored near sodium hypochlorite or potassium permanganate because contact releases chlorine gas. It must also be segregated from cyanide-bearing materials, which react to form hydrogen cyanide. Venting should be through a packed scrubber charged with dilute caustic; direct atmospheric venting of fuming-grade acid is not acceptable under most local air permits. Transfer piping should avoid threaded joints in favor of welded socket connections, and gasket materials should be PTFE or EPDM rather than natural rubber for hot acid service above 50 °C. Dilution of concentrated hydrochloric acid is strongly exothermic. The heat of solution for hydrogen chloride gas in water is approximately 74.84 kJ/mol at infinite dilution. When preparing dilute baths, acid is added slowly to water, not water to acid, to reduce localized boiling and aerosol release.

In demineralizer regeneration at power stations and semiconductor water plants, hydrochloric acid is diluted to 5–10 wt% and passed through cation exchange resin beds. The quotation should state the regeneration cycle frequency, the resin manufacturer’s maximum free chlorine or iron tolerance, and whether the spent regenerant is neutralized before discharge. In high-purity water circuits, electronic-grade hydrochloric acid may require transition metal reporting below 1 mg/kg, with buyers supplying maximum sodium, calcium, iron, and zinc thresholds because these residuals can shorten resin life or contaminate downstream membranes. Published data for specific electronic-grade threshold levels is limited outside supplier specifications; buyer maximums are required for a firm quotation.

For oil well acidizing, hydrochloric acid is frequently supplied at 15%, 28%, or 31.45% concentration with corrosion inhibitor packages added at the wellhead. The quotation must state the formation type, expected bottomhole temperature, and intended dilution water quality because these factors control inhibitor demand, acid strength, and potential ferric hydroxide precipitation. For pipeline descaling and industrial cleaning, the inquiry should specify the scale composition, the base metal, the circulation temperature, and the contact time so that the supplier can assess whether hydrochloric acid alone is appropriate or whether a mixed acid or inhibitor system is required.