Safety Alert Nitric Acid

Nitric acid incident in a university lab prompts improved safety practices

18 May 2018

Nitric acid is a strong oxidizing agent recognized for its ability to enhance combustion of other substances. This is why it is used in the production of explosives such as nitroglycerin and TNT.

A recent incident in a U of A laboratory illustrated the explosive properties of nitric acid, particularly when combined with organic substances.

The incident-a blast event-occurred after a researcher heated an autoclave reaction vessel containing nitric acid and organic residue. The reaction lead to an uncontrolled pressure increase, which caused the vessel to explode.

The blast ejected the autoclave cap and body through the side of an oven. The autoclave body ricocheted off shelving and fell to the floor. The cap passed through a partition wall and struck the far wall of the laboratory next door.

Working safely with nitric acid

1. Complete a hazard assessment & implement control measures

  • Anticipate possible by-products and heat generation when mixing nitric acid with organic materials.

  • When heating nitric acid, conduct work in a fume hood with the sash set at the proper height. As an added precaution, use a chemical fume hood safety shield.

2. Store it safely

  • Store nitric acid separately, in its original container and in a dedicated acid cabinet.

  • If a dedicated storage cabinet is not available, store nitric acid in an acid cabinet with other inorganic acids.

3. Dispose of waste properly