Theoretical and practical comparison of the potassium iodide tracer method(KI-Discus) for assessing the containment efficiency of fume cupboards with the gas tracer method described in BS 7258: 1994: Part 4

Attempts have been made by manufacturing groups, health and safety legislat ors and national and international standards bodies to standardise containm ent testing strategies for open fronted containment systems. It is importan t that all the strategies and testing methods used should yield comparable results. However, there are a number of test methodologies that have not be en standardised or correlated, and the results between them cannot be compa red. Manufacturers of contamination control equipment have the expense of t esting by varying methods in different countries where standards apply. Ult imately, it is hoped that there will be either one standard method for test ing all open fronted containment facilities, or, if there are different met hods, that they yield results which can be compared. In this paper a theore tical and practical comparison is made of the KI-Discus test method for ass essing fume cupboard performance and the tracer gas method recommended in B S 7258, 1994: Part 4. Comparison of these two methods for testing fume cupb oards was found not to be practicable due to fundamental differences in 1) the philosophy of the tests, 2) the tracers used, 3) their method of genera tion, 4) the disposition of equipment and 5) the sampling methods. It is de monstrated that the KI method is more sensitive than the gas method and tha t the philosophy of the KI method is to detect actual leakage whereas, the gas method detects potential leakage (viz, contamination reaching the plane of the aperture). (C) 1999 British Occupational Hygiene Society. Published by Elsevier Science Ltd. All rights reserved.