Mock-up and testing of a variable volume laboratory fume hood exhaust system

Abstract

A test of an ANL-designed variable volume system prototype used to displace an existing constant volume fume hood ventilation system in a laboratory of the Materials Science Division is described. Performance characteristics such as response, stability, repeatability and hood containment were tested and evaluated, with particular emphasis on containment, to clearly demonstrate that operator safety and the environment are not compromised. Results obtained clearly indicate the feasibility of implementing the prototype concept. The variable volume system enables reducing conditioned ventilation air to the laboratory room by at least 50%, dependent solely upon internal heat loads. Normal hood exhaust of 200 CFM with the face sash in a closed position can be provided by air used to condition building offices and corridors. In all modes of operation, i.e., fume hood face sash closed to fully open, the building differential pressure design criteria from office to corridor to laboratory to fume hood is maintained. Also, hood face velocity can be established to meet minimum requirements at any position of sash opening and test results indicate a hood containment efficiency equal to or better than the presently existing constant volume proportional by-pass system.