TABLE 4-1 Physical and Chemical Properties of Hydrogen Fluoride


Anhydrous hydrofluoric acid

CAS registry number


Molecular formula


Molecular weight


Boiling point


Melting point


Flash point


Explosive limits


Specific gravity

1.002 at 0°C/4°C

Vapor pressure

917 mmHg at 25°C


Very soluble in water and alcohol; slightly soluble in ether; soluble in many organic solvents

Conversion factors

1 ppm = 0.82 mg/m3; 1 mg/m3 = 1.22 ppm

Abbreviation: NA, not available or not applicable.

Sources: Budavari et al. (1989) and HSDB (2008).

(ATSDR 2003). Ambient air concentrations of hydrogen fluoride are typically below the detection limit, although concentrations may be higher near industrial facilities that use or produce hydrogen fluoride (ATSDR 2003).

Hydrogen fluoride has been measured on board submarines. NRC (1988) listed hydrogen fluoride as a potential contaminant of submarine air and reported a concentration of 0.3 ppm. No information was provided on sampling protocol, location, operations, or duration. Trials conducted on three nuclear-powered attack submarines did not detect hydrogen fluoride; the level of detection was about 3 ppb (Hagar 2008). Whether the reported results are representative of the submarine fleet is not known; few details were provided about the conditions on the submarines when the samples were taken. No other exposure data were located. Hydrogen fluoride emissions aboard submarines are thought to arise from decomposition of halogenated hydrocarbons and refrigerants (Hagar 2008).


Hydrogen fluoride and its aqueous solutions present an acute hazard by inhalation or dermal exposure. The primary target of airborne gaseous hydrogen fluoride is the respiratory tract; however, injury to distant organs may also occur because of absorption of substantial amounts of fluoride. Acute effects of hydrofluoric acid include damage to skin and lungs, including severe burns, and sys-

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