Flammability and Explosibility

Sulfur dioxide is a noncombustible substance (NFPA rating = 0).

Reactivity and Incompatibility

Contact with some powdered metals and with alkali metals such as sodium or potassium may cause fires and explosions. Liquid sulfur dioxide will attack some forms of plastics, rubber, and coatings.

Storage and Handling

Sulfur dioxide should be handled in the laboratory using the "basic prudent practices" described in Chapter 5.C, supplemented by the procedures for work with compressed gases (Chapter 5.H).


In the event of skin contact, immediately wash with water and remove contaminated clothing. In case of eye contact, promptly wash with copious amounts of water for 15 min (lifting upper and lower lids occasionally) and obtain medical attention. If large amounts of this compound are inhaled, move the person to fresh air and seek medical attention at once.

Leaks of sulfur dioxide may be detected by passing a rag dampened with aqueous NH3 over the suspected valve or fitting. White fumes indicate escaping SO2 gas. To respond to a release, use appropriate protective equipment and clothing. Positive pressure air-supplied respiratory protection is required. Close cylinder valve and ventilate area. Remove cylinder to a fume hood or remote area if it cannot be shut off. If in liquid form, allow to vaporize.


Excess sulfur dioxide should be returned to the manufacturer if possible, according to your institution's waste disposal guidelines. For more information on disposal procedures, see Chapter 7 of this volume.

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