Hydrogen fluoride / HF

Hydrogen fluoride

Gas Identification

Other denomination
Hydrofluoric acid
CAS Registry Number
SCBA type

Chemical properties

Molecular formula
Molecular mass
20 g/mol

Physical properties

Boiling point
20 °C
Autoignition temperature
Gas/Vapour density
15,98 eV

Flammability limit


Threshold limit value

1,8 ppm • 1,5 mg/m³
3 ppm • 2,5 mg/m³

Hydrogen fluoride : Description and use


In the production of aluminium, baths of molten alumina containing fluorides may release hydrogen fluoride, as with some welding procedures when fluxes containing fluorides are used. Volcanoes and sea salt aerosols are natural sources of hydrogen fluoride. Upon contact with the humidity in the air, the hydrogen fluoride released into the atmosphere forms hydrofluoric acid. Anhydrous hydrogen fluoride is a gas at room temperature. As its boiling point is more or less 20°C, it can be sold in gas cylinders or gas tanks or as a fuming liquid. Various concentrations of aqueous solutions are also commercially available labelled as hydrofluoric acid.
It has a pungent odour, is extremely corrosive and can be liquefied very easily.

Flammability and explosiveness: Anhydrous hydrogen fluoride is a non-flammable and non-explosive compound. However, in the presence of humidity, it is corrosive to almost all metals and the reaction releases hydrogen, which is an extremely flammable and explosive gas.

  • In the production of fluorocarbons and chlorofluorocarbons
  • In aluminium smelters, in the production of aluminium fluoride and synthetic cryolite (aluminium and sodium fluorides) which make up baths of molten alumina used to produce aluminium by electrolysis
  • In the production of petrol, as a catalyst in alkylation processes
  • In electronics for engraving and polishing silicon plates
  • In the chemical industry to produce pure fluorine and inorganic fluorines
  • In the nuclear energy industry to produce uranium hexafluoride which is used in the isotopic enrichment of uranium
  • In the production of hydrofluoric acid, which in turn has many uses

Hydrogen fluoride : Warnings and caution

GHS hazard statements

H330 - Fatal if inhaled.
H310 - Fatal in contact with skin.
H300 - Fatal if swallowed.
H314 - Causes severe skin burns and eye damage.

GHS precautionary statements

P101 - If medical advice is needed, have product container or label at hand.
P102 - Keep out of reach of children.
P260 - Do not breathe gas/mist/vapours/spray.
P262 - Do not get in eyes, on skin, or on clothing.
P280 - Wear protective gloves/protective clothing/eye protection/face protection.
P321 - Specific treatment: on skin, apply calcium gluconate gel at 2.5%; perform subcutaneous injection with solution at 10% at the rate of 0.5mL/cm2 of burn.
P361 - Remove/Take off immediately all contaminated clothing.
P403 - Store in a well-ventilated place.
P405 - Store locked up.
P303+P361+P353 - IF ON SKIN (or hair): Remove/Take off immediately all contaminated clothing. Rinse skin with water/shower.
P307+P311 - IF EXPOSED: Call a POISON CENTRE or doctor/physician.

SGH06 : Toxique
SGH05 : Corrosif