CH-2438 (RP-70) -- The Effect of Room Air Challenge on the Efficiency of Laboratory Fume Hoods ✓ Most Recent

Neither the ASHRAE HANDBOOK & PRODUCT DIRECTORY nor any other laboratory design or safety manual contains adequate information on designing, selecting, sizing, adjusting, testing and maintaining fume hoods. Many noted authors have recognized the critical nature of air supply distribution, laboratory furniture arrangement, auxiliary air supply and other external influences upon hood performance, but none have integrated all factors into a comprehensive criteria. Others have developed quantitative performance measuring techniques using high sensitivity gas chromatography, but there is no recognized standard test procedure.

In addition to a standard test procedure, basic lab hood performance criteria are badly needed. The performance criteria and the test procedure are mutually interdependent. The existing performance criteria, although the best available, are committee consensus efforts, only part of which have any demonstrable backing of objective, quantitative data. Moreover, the available criteria of this type are in disagreement and are inconsistent.

Significant investigations which form the basis for present standards have been made by several investigators (see Bibliography). None of these, however, taken separately or together can satisfy the needs for performance criteria.

The first phase of this research project was based on the premise that a good performance test, was basic to the pursuit of criteria for (1) the design of room air supply distribution, type and arrangement of air diffusers, and (2) the design, selection, sizing, testing and maintenance of fume hoods for research laboratories or industrial laboratories.

The criteria for a standard performance test were as follows:

1. Reasonably representative of actual challenges to hoods
2. Practical for field use to test hoods as installed, taking
into account the effect of general room ventilation and all other "as installed" factors
3. Practical for shop use, for developers or manufacturers of hoods
4. Nonhazarqousand noncontaminating for most circumstances
5. Sufficiently inexpensive and convenient to lead to adoption
as an ASHRAE standard