Field Results of an In-Place, Quantitative Performance Test for Laboratory Fume Hoods

Abstract

A new method for testing fume hood performance was developed and previously reported. It involves measurement of tracer chemical concentrations outside a hood that result from a steady release of sulfur hexafluoride tracer chemical inside the hood. The tracer chemical is released through a hollow rectangular diffuser that encloses the entire work area. Field surveys on 50 laboratory fume hoods belonging to three different organizations demonstrated the ease and usefulness of this method for determining hood performance and the magnitude of personnel exposures under realistic operating conditions. The most frequent contributions to unsatisfactory hood containment were lack of a bottom airfoil, excessive clutter inside the work space, sharp sash edges, and improper delivery of replacement air. Seven case studies, presented to illustrate the unique findings of these surveys, include homemade hoods, hoods with horizontal sliding sashes, auxiliary air hoods, and variable exhaust volume hoods. One of the most useful properties of this test is that the quantified effects of poor work practices can be communicated immediately to the hood user. The test procedure can be used as an educational tool to teach laboratory personnel how a fume hood works and why poor laboratory techniques adversely affect a fume hood's protective function.