Hydrochloric Acid: Uses, Strengths and Safety Data Sheet Guide

Hydrochloric acid is a solution of hydrogen chloride gas (HCl, CAS 7647-01-0) in water. Concentrated commercial acid is around 31 to 37 percent HCl and gives off visible, pungent fumes in humid air. It is sometimes sold under the older name muriatic acid, particularly for masonry cleaning and pool use. The substance is both a gas and a solution in trade, so check which form your product is before you write documents.

What hydrochloric acid is used for

• Steel pickling, where it removes rust and scale before galvanising or coating.
• Acidising oil and gas wells, to dissolve carbonate rock and improve flow.
• Regenerating ion-exchange resins in water treatment and adjusting pH.
• Producing chlorides such as calcium chloride, ferric chloride and aluminium chloride.
• Food processing, as an acidity regulator and in producing sweeteners and gelatin, using food-grade acid.
• Descaling and cleaning products for concrete, tile, boilers and metal.
• Laboratory analysis, titration and sample digestion.

Strength matters for classification

Hydrochloric acid at high concentration is classified as causing severe skin burns and eye damage (skin corrosion category 1B, H314), and it also carries a respiratory irritation statement (H335) at stated concentrations. It is often also labelled as corrosive to metals (H290). The signal word is Danger and the pictogram is corrosion (GHS05), with an exclamation mark added where the respiratory statement applies. Specific concentration limits in the harmonised entry mean that a 10 percent solution is classified differently from a 33 percent solution, so you should classify each strength you sell rather than copy one SDS across the range.

Handling hazards

The main hazards are burns and inhalation. Acid mist and fumes irritate the nose, throat and lungs, and a large release can generate a dense irritant cloud. Work in well-ventilated spaces or with local exhaust, and wear splash goggles, a face shield, acid-resistant gloves, an apron and, where fumes exceed exposure limits, suitable respiratory protection. Hydrochloric acid reacts with many metals to release flammable hydrogen, and with bleach or other hypochlorites to release toxic chlorine gas.

That last point deserves its own line in Section 10 and Section 7: never mix hydrochloric acid with sodium hypochlorite or other oxidising cleaners. It is a common cause of accidents in cleaning and pool-treatment settings.

Storage

Use containers made of high-density polyethylene, polypropylene, rubber-lined steel or glass-lined steel. Avoid ordinary metals. Vent containers carefully because fuming acid can build up pressure or corrode closures. Keep it separated from bases, oxidisers, cyanides, sulphides and reactive metals. Our storage compatibility guide shows how to set up the segregation groups.

Documents and transport

The SDS needs the strength in Section 3, exposure limits for hydrogen chloride in Section 8 (a ceiling limit applies in many jurisdictions), reaction hazards in Section 10, and a Class 8 transport entry in Section 14. Check the current UN number and packing group with your carrier. For comparison with other mineral acids, read our guides on sulfuric acid and nitric acid. The classification we hold is on the hydrogen chloride page.