Hydrochloric acid (37%) COSHH assessment guide

Strong hydrochloric acid is used for descaling, brick and patio cleaning, and metal treatment. At this strength it causes severe burns, can corrode metals, and its fumes irritate the airways.

Taken from the Hydrochloric acid S.G. 1.18 (about 37%) safety data sheet from Fisher Scientific UK, revision 18 October 2023. Open the data sheet. Formulas differ between products, so check against the sheet for the product you actually buy. This is a laboratory-grade sheet. Trade products sold under the same name can have a different strength and different hazards. It applies to acid at about 37%. Below 25% the sheet lists different classifications, so diluted trade products differ.

Hazards on the data sheet

Signal word: Danger.

H290 May be corrosive to metals
H314 Causes severe skin burns and eye damage
H335 May cause respiratory irritation

Precautions

P234 Keep only in original packaging
P280 Wear protective gloves/protective clothing/eye protection/face protection
P303 + P361 + P353 IF ON SKIN (or hair): Take off immediately all contaminated clothing. Rinse skin with water or shower
P304 + P340 IF INHALED: Remove person to fresh air and keep comfortable for breathing
P305 + P351 + P338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing
P310 Immediately call a POISON CENTER or doctor/physician

Workplace exposure limit

Long-term (8-hour): 1 ppm or 2 mg/m³. Short-term (15-minute): 5 ppm or 8 mg/m³. From EH40/2005 Table 1, under hydrogen chloride (gas and aerosol mists).

PPE

Eyes	Goggles (European standard - EN 166).
Hands	Protective gloves. All > 480 minutes, EN 374: Butyl rubber 0.5 mm, Nitrile rubber 0.35 mm, Neoprene gloves 0.5 mm, Viton (R) 0.4 mm, PVC 0.5 mm.
Breathing	Certified respirators when facing concentrations above the exposure limit. Large scale/emergency: Particulates filter conforming to EN 143 or Acid gases filter: Type E, Yellow. Small scale/laboratory: EN 149:2001 approved respirator; half mask EN405, or EN140 plus filter EN 141.
Skin	Long sleeved clothing.

First aid

Eyes	Rinse immediately with plenty of water, also under the eyelids, for at least 15 minutes. Immediate medical attention is required.
Skin	Wash off immediately with plenty of water for at least 15 minutes. Immediate medical attention is required.
Breathed in	Remove to fresh air. If breathing is difficult, give oxygen. Do not use mouth-to-mouth method if victim ingested or inhaled the substance; use a pocket mask with a one-way valve or other proper respiratory medical device. Immediate medical attention is required.
Swallowed	Do NOT induce vomiting. Call a physician or poison control center immediately.

Storage, spills and what to keep it away from

Storage	Keep containers tightly closed in a dry, cool and well-ventilated place. Corrosives area.
Spills	Evacuate personnel to safe areas and keep people away from and upwind of spill/leak. Ensure adequate ventilation. Soak up with inert absorbent material. Keep in suitable, closed containers for disposal.
Keep away from	Metals. Strong oxidizing agents. Bases. sodium hypochlorite. Amines. Fluorine. Cyanides. Alkaline.

What your assessment still has to cover

Record the strength you actually buy, the area treated and how fumes clear from it. This sheet lists sodium hypochlorite among the materials to avoid, so note whether bleach is used in the same place.

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