Hydrofluoric Acid 

General

Hydrofluoric acid (HF) is an extremely corrosive acid. It is a colorless liquid at normal atmospheric pressure and temperatures less than 19oC.  Above the temperature of 19oC it turns into a gas. 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. 

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. 

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.   

• • Symptoms from exposure to dilute solutions of HF or low concentrations of HF vapor might be delayed.  
  • Burns from HF solutions with less than 50% concentration may not be felt immediately, and burns from HF solutions of 20 % or less concentration can take hours to become visible.   
  • The burns are characterized by the 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 

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. 
• Researchers 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. Inspect the gloves and apron made out of PVC and replace before they break. 
• Laboratory attire must include: a face shield (or safety glasses), Neoprene gloves, apron or lab coat. 
• Safety shower and eye wash stations must be located near the area where HF is being used. 
• Keep calcium gluconate gel and drops handy in case of an emergency. Calcium gluconate first aid kit is commercially available from a number of vendors including HF Acid Safety and First Aid Products. 
• HF should be stored away from incompatible chemicals 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. 

Emergencies 

If the event of skin / eye contact, vapor inhalation or ingestion, follow the procedures below and notify NUPD immediately by dialing x3333 or using the SafeZone App for emergency medical assistance.  

In cases where the first aid 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 fresh air.  
• 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 the first aid 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.  
• Restock the first aid kit after usage as soon as possible.  

Questions

In the event of a spill or medical emergency, contact NUPD via your Safezone app or (617) 373 3333. 

Contact the OARS office for non-emergency questions about working safety with HF.