LABORATORY CHEMICAL SAFETY SUMMARY: HYDROGEN FLUORIDE AND HYDROFLUORIC ACID

Substance

Hydrogen fluoride and hydrofluoric acid

CAS 7664-39-3

 

Formula

HF

 

Physical Properties

Colorless, clear, fuming liquid

Anhydrous HF: bp 20 °C, mp -83 °C

Miscible with water

 

Odor

Acrid, irritating odor

 

Vapor Pressure

Anhydrous HF: 775 mmHg at 20 °C

Hydrofluoric acid: 14 mmHg at 20 °C

 

Flash Point

Noncombustible

 

Toxicity Data

LCLO inhal (humans)

50 ppm (0.5 h)

 

PEL (OSHA)

3 ppm (as fluoride)

 

TLV-TWA (ACGIH)

3 ppm (2.6 mg/m3; ceiling as fluoride)

Major Hazards

Extremely corrosive liquid and vapor that can cause severe injury via skin and eye contact, inhalation, or ingestion.

Toxicity

Anhydrous hydrogen fluoride and hydrofluoric acid are extremely corrosive to all tissues of the body. Skin contact results in painful deep-seated burns that are slow to heal. Burns from dilute (<50%) HF solutions do not usually become apparent until several hours after exposure; more concentrated solutions and anhydrous HF cause immediate painful burns and tissue destruction. HF burns pose unique dangers distinct from other acids such as HCl and H2SO4: undissociated HF readily penetrates the skin, damaging underlying tissue; fluoride ion can then cause destruction of soft tissues and decalcification of the bones. Hydrofluoric acid and HF vapor can cause severe burns to the eyes, which may lead to permanent damage and blindness. At 10 to 15 ppm, HF vapor is irritating to the eyes, skin, and respiratory tract. Exposure to higher concentrations can result in serious damage to the lungs, and fatal pulmonary edema may develop after a delay of several hours. Brief exposure (5 min) to 50 to 250 ppm may be fatal to humans. Ingestion of HF can produce severe injury to the mouth, throat, and gastrointestinal tract and may be fatal.

HF has not been reported to be a human carcinogen. No acceptable animal test reports are available to define the developmental or reproductive toxicity of this substance.

Flammability and Explosibility

Hydrogen fluoride is not a combustible substance.



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