Is a special perchloric acid fume hood necessary for all uses of perchloric acid?
A. No, definitely not. The purpose of a fume hood is to remove the hazardous vapors or gases generated in the work being done. Use of cold or dilute perchloric acid does not result in any hazardous vapors or gases and does not require a hood at all. If other vapors or gases are generated such as hydrogen or hydrogen sulfide, any fume hood can be used. The perchloric acid fume hood is intended for removal of acid vapors that result when perchloric acid is evaporated and vented to the atmosphere. This only happens when perchloric acid is concentrated and heated to a point where the vapors can escape the container. At room temperatures, concentrated perchloric acid evaporates very slowly. In fact, it will absorb moisture from the atmosphere to which it is exposed until a balance is achieved in concentration and relative humidity. 17. We don't have a perchloric acid fume hood and only do an occasional procedure where we have to evaporate some perchloric acid. What should we do? A. Sev
