Hydrofluoric Acid

Northeastern University Procedure for the Safe Handling and Use of Hydrofluoric Acid

I.General:

Hydrofluoricp acid(HF) is a colorless liquid at normal atmospheric pressure and temperatures less than 19^oC.  Above the temperature of 19^oC it turns into a gas.  It is an extremely corrosive.  HF is commonly used for etching glass, pickling of stainless steel, digesting minerals and as a laboratory reagent. HF is industrially available as anhydrous hydrofluoric acid and aqueous hydrofluoric acid.

II. Toxicity:

Exposure to HF can be very lethal to humans, animals and plants.  The liquid and vapor can cause severe injury via skin and eye contact, inhalation, or ingestion. HF can penetrate the skin very easily by damaging the underlying tissue.  The fluoride ion causes the destruction of soft tissue and decalcification of the bones.

III. Injuries Caused By HF Exposure:

Short Term or Acute

• Both liquid and vapor forms of HF cause severe and slow healing burns on contact with the skin, eyes, or mucous membranes.  Burns from dilute solutions of HF or low concentrations of HF vapor might not be immediately visible or painful. Burns from HF solutions with less than 50% concentration may not be felt immediately. B urns from HF solutions of 20 % or less concentration can take hours to become visible.  The burns are characterized by appearance of a tough white coagulation with persistent excruciating pain, progressive destruction of tissue which could include decalcification and necrosis of bone.
• Inhalation of gas or vapor may cause lung edema and convulsions.
• Ingestion can cause burning of mouth and pharynx, nausea, vomiting, and abdominal pain

Long Term or Chronic (Long term poisoning is not common)

• Skin ulcers.
• Bone and teeth damage.
• Irritation of nose, throat and bronchi.

IV. Safe Workplace Practices:

• Ensure that HF is handled by highly trained, adequately protected and responsible personnel.
• All work with HF must be done in a fume hood.
• If HF is used in experiments done outside the fume hood, adequate ventilation must be present to ensure that the HF atmospheric concentration does not exceed permissible limits.
• Individuals working with  HF must wear personal protective equipment made of materials such as polyvinyl chloride (PVC) or chlorobutadiene (Neoprene). Note: PVC material degrades in presence of HF so inspect the gloves and apron made out of this material and replace before they break.
• Laboratory attire must include: a face shield (or safety glasses), Neoprene gloves, apron or lab coat.
• The safety shower and eye wash must be located near the area where HF is being used.
• Keep calcium gluconate gel  and drops handy in case of an emergency.
• HF should be stored away from incompatible chemical and materials.  Corrosive action of HF on metals can result in the formation of hydrogen in containers and piping to create fire and explosion hazards, so potential sources of ignition should be excluded from the areas where HF is used and stored.
• Use minimum quantities of HF and where possible, use a less dangerous substitute.
• Make sure more than one person is present during HF usage.

V. Emergencies:

• If the event of skin / eye contact, vapor inhalation or ingestion, follow the procedures below and have someone immediately dial ext. 3333 for medical assistance. The Lane Health Center can provide treatment with calcium gloconate during normal business hours.
• In cases where the emergency kit (calcium gluconate gel and drops) is not available in the lab:
• If skin contact occurs immediately place the individual under the safety shower.  Remove all the clothing.  Handle the HF-contaminated material with gloves.  Keep washing the contaminated area for minimum of 15 minutes. 
• If eye contact occurs flush the eye with water for 30 minutes.  Then place eye packs on the eyes till the medical assistance arrives.
• In case of vapor inhalation remove the individual to uncontaminated  atmosphere.
• In case of Ingestion give copious quantities of lime water, milk or water drinks in spite of vomiting.
• Seek medical treatment following all the above procedures.

• In cases where emergency kit (calcium gluconate gel and drops)is available in the lab:
• If skin contact occurs immediately remove the contaminated clothing and flush off the acid using large quantities of cool water for 5 minutes. Apply calcium gluconate on and around the burn.  Massage it in with gloved hands until 15 minutes after the pain has subsided.
• If eye contact occurs flush the eyes with large quantities of cool clean water for 5 minutes while holding the eyelids apart.  Then administer calcium gluconate drops.

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  • Hydrofluoric Acid
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