When should a vented cap be used on waste containers?

Hydrogen peroxide, strong oxidizing acids such as nitric, perchloric and sulfuric acids and mixtures such as Piranha or Aqua regia are used as etches to remove organic residues from silicon wafers and other research materials. These chemicals are dangerous because of their strong corrosivity and the tendency of such waste solutions to evolve gas due to oxidation of organics or decomposition. When such wastes are collected, pressurization from gas generation in the container becomes a safety risk.

A vented cap should be used in labs on campus who generate wastes from use of the above chemicals/solutions. We know from inspections and experience this occurs in Material Science and Engineering, Geology, Electrical and Computer Engineering, Mechanical Engineering, Biology, Chemistry, and may, of course, be elsewhere.

Special care must be taken if you generate waste containing these chemicals. Read about other important safety precautions: Vented Waste Caps FAQ