Working with hydrogen fluoride and related substances

Hydrogen fluoride/hydrofluoric acid are highly corrosive compounds that can easily penetrate skin and muscles and destroy cell membranes and nerves. If you have an accident with hydrofluoric acid, you need to get immediate first aid treatment.

Norsk versjon - Arbeid med hydrogenfluorid -flussyr og HF-gass

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What is hydrogen fluoride (hydrofluoric acid and HF gas)?

HF - Hydrogen fluoride (CAS no. 7664-39-3) is a colourless, toxic gas with a sharp odour. The gas liquefies at 19.5ºC to a strong fuming, toxic liquid.

Hydrofluoric acid is an aqueous compound of hydrogen fluoride. Despite it being a weak acid, hydrofluoric acid is a highly corrosive compound.

Hazards when using HF

HF/hydrofluoric acid easily penetrates the skin and muscles, rapidly destroying cell membranes and nerves, causing necrosis. People who are exposed can also develop systemic effects such as cardiac dysrhythmia and cramps.

Hydrogen fluoride gas is converted to hydrofluoric acid when in contact with the moisture in eyes, mucous membranes and skin. The progression of damage and effects are the same as for HF/hydrofluoric acid in general.

NB! It can take several hours before pain and injury develop in body tissue. Hence it is very important that you do not underestimate the seriousness of the situation, even if you have no symptoms immediately after exposure. The period of time from exposure to hydrofluoric acid to pain and corrosion depends on the concentration:

Concentration of hydrofluoric acid Time before developing symptoms

0 - 20 per cent Up to 24 hours

20-50 per cent 1-8 hours

> 50 per cent Immediately

For solutions over 50%, systemic effects occur when more than 1% of the skin surface is exposed. For solutions of any concentration, systemic effects occur when more than 5% of the skin surface is exposed. A person's palm is equal to 1% of their skin surface. Systemic effects might also occur as a result of oral consumption or inhalation.

Precautions BEFORE working with HF

The person in charge of the work must make sure that

  • All new projects are subjected to a risk assessment.
  • The existing risk assessment is revised when a previous project is continued.
  • Local procedures are developed for handling of HF/hydrofluoric acid, as well as first aid instructions and contingency plans where necessary.
  • All individuals who are working with hydrofluoric acid or hydrogen fluoride gas have adequate training. Preferably, everyone should have attended a course before work begins, or at least as soon as possible. Report any course requirements to the HSE department (in Norwegian). If there are no scheduled courses before work starts, the person in question must be trained by a person who has attended the course and is an experienced "HF user".
  • All employees who are working with hydrofluoric acid or hydrogen fluoride gas must be familiar with the contents of the risk assessment.
  • All employees who are working with hydrofluoric acid or hydrogen fluoride gas must be familiar with first aid procedures and know the location of necessary first aid equipment.
  • An updated safety data sheet is available. The safety data sheet should be brought to the hospital if anyone needs medical attention.
  • Preparations for use in case of emergency (in Norwegian) must be obtained. The information on "Hydrogenfluorid (flussyre og hydrogenfluoridgass) - behandling ved forgiftning" (Treatment of corrosion and systemic effects from exposure to hydrogen fluoride (hydrofluoric acid and hydrogen fluoride gas) should be kept together with the preparations for use in case of emergency. The information should be brought to the hospital if anyone needs medical attention.
  • Available respiratory protective device in case of fumes/aerosols. When using a respirator: Use a grey and yellow combination filter for inorganic gases, labelled ABEK.
  • Tests of the emergency shower and eyewash are conducted regularly

Persons working with hydrofluoric acid must make sure

  • To have adequate training and necessary information to be able to perform the work in a safe manner.
  • To be familiar with risk assessments, local procedures for handling HF/hydrofluoric acid, first aid instructions and contingency plans.
  • To be extra careful when handling hydrofluoric acid if you are suffering from heart failure or low blood pressure. You might want to consider not working with the substance. You should not use the preparation Calcium-Sandoz® effervescent tablets.

Precautions WHEN working with hydrofluoric acid

  • Always work in a fume hood or in a well ventilated location.
  • Always use suitable protective equipment in accordance with the risk assessment: Face guard, suitable gloves (there are a number of different types of gloves, make sure to use the right type according to which concentration you use, the need for motoric precision etc.), lab coat, collars, polyurethane boots/gaiters/shoe covers, possibly a polyurethane apron or a boiler suit.
  • Do not use contact lenses. Squirts to the eyes can get behind the lenses, causing the lenses to stick to the eye.
  • Avoid hydrofluoric acid coming in contact with metals, alkali metals, glass, potassium permanganate, fluorine, silicon, alkalis (bases) and phosphorus oxides. If hydrofluoric acid comes in contact with hydrogen gas, it can cause an explosive reaction when combined with air.
  • Bottles, cans etc. containing hydrofluoric acid must be clearly labelled with name and compulsory warnings. Contain them at a ventilated location.
  • Spill containing hydrofluoric acid must be neutralized with a suitable, calcareous absorbent and wiped up.
  • All kinds of waste that is or may be contaminated with hydrofluoric acid must be disposed as chemical waste.

Preparations for use in case of emergency

  • HF-antidot gel®, a minimum of one 25 gram tube per person working with hydrofluoric acid. Item no. 273680. Contact the HSE department (in Norwegian) which will fill out a registration exemption form signed by the occupational physician (in Norwegian). Bring the form to the pharmacy.
  • Calcium-Sandoz® effervescent tablets, two packs of 20 tablets per person working with hydrofluoric acid. Item no. 193821. Can be bought prescription-free in pharmacies in packs of 20 tablets of 500 mg.
  • Compressive bandages.
  • An adequate number of bottles of eyewash liquid (saline solution) for use during transportation to the hospital.

Typical symptoms and clinical signs of exposure

Spills on skin

  • Intense pain. Corrosion and the increase of tissue damage continues as long as the pain persists.
  • Redness (erythema), accumulation of fluid (oedema) and blisters.
  • Any decolourisation of the skin and formation of hard coagulated skin.
  • Necrosis in the deeper tissues. Loss of lime and corrosion in underlying bones.

Squirts to the eyes

  • Pain, conjunctivitis, lacrimation, oedema, increased pressure in the eye (glaucoma), damage to the cornea, impact on or loss of vision and scarring.

Inhalation (inhalation of fumes or gas)

  • Inhalation can cause a wide range of effects, from mild symptoms in the upper respiratory tract to constriction of airways, bleeding, pulmonary oedema and death.
  • Coughing, a burning sensation in the airways, chest pain, short-windedness and blue-coloured skin caused by low oxygen supply.


  • High risk of corrosion in mouth, oesophagus and stomach, together with systemic effects. The ingestion of even relatively dilute solutions can be fatal.
  • Nausea, vomiting and diarrhoea.
  • Sores and bleeding in mouth, oesophagus and stomach.
  • Intense pain.
  • Constriction of the upper respiratory tract.

First aid in case of accidents involving HF

Immediate first aid treatment is crucial to reduce the damage of accidents involving hydrofluoric acid.

NB! Individuals performing first aid must use protective equipment to ensure their own safety. Call 113 or the Norwegian Poison Information Centre (tel.: 22 59 13 00) after starting first aid treatment.

Injured persons must be taken to a hospital as quickly as possible. Remember to bring the safety data sheet and the Norwegian Poison Information Centre's letter "Hydrogenfluorid (flussyre og hydrogenfluoridgass) - behandlingsanbefaling ved forgiftning" (Treatment of corrosion and systemic effects from exposure to hydrogen fluoride (hydrofluoric acid and hydrogen fluoride gas)) to the hospital.

Spills on skin

1. Rinse immediately and thoroughly with large amounts of water. Use a shower if larger areas of the skin is exposed. Remove clothes, shoes, jewellery, watches etc., and keep rinsing for up to five minutes. Important: Keep rinsing during transportation to the hospital if step 2 or 3 cannot be carried out.

2. Immediately following step 1, start treatment with HF-antidot gel®: Wipe the skin clean and apply plenty of HF-antidot gel®. Rub the ointment into the skin. If the hand is exposed, one can fill a rubber glove with HF-antidot gel® and wear it on the exposed hand. Continue the treatment during transportation to the hospital.

3. If HF-antidot gel® is not available: Dissolve Calcium-Sandoz® effervescent tablets in water (20 tablets in 2 litres of water). Keep the injured hand or foot in the solution. If you have spilled on other parts of the body: Apply compresses completely soaked with the solution to the skin. Change the compresses frequently. The solution should penetrate the skin. Continue the treatment during transportation to the hospital.

Squirts to the eyes

Rinse immediately with large amounts of water for at least 30 minutes. Continue the rinsing during transportation to the hospital.

The eyelids and/or the skin around the eyes is often also exposed together with the eyes. See treatment for spills on the skin.

Inhalation (inhalation of aerosols, fumes or gas)

Evacuate the area. Go outside for fresh air. Avoid physical exertion.


Give plenty of drink immediately, preferably milk. Give 10-20 Calcium-Sandoz® effervescent tablets dissolved in water. Precaution:// Calcium-Sandoz® effervescent tablets should not be given to individuals with heart failure or low blood pressure.

Do not induce vomiting. Do not give activated carbon. Ingestion also causes risk of inhalation injury.


NTNU regulations



Approved by HSE manager - 13th of October 2015 - HMSR08E - ePhorte 2016/3901