| Popis: |
Attempts have been made by manufacturing groups, health and safety legislators and national and international standards bodies to standardise containment testing strategies for open fronted containment systems. It is important that all the strategies and testing methods used should yield comparable results. However, there are a number of test methodologies that have not been standardised or correlated, and the results between them cannot be compared. Manufacturers of contamination control equipment have the expense of testing by varying methods in different countries where standards apply. Ultimately, it is hoped that there will be either one standard method for testing all open fronted containment facilities, or, if there are different methods, that they yield results which can be compared. In this paper a theoretical and practical comparison is made of the KI–Discus test method for assessing fume cupboard performance and the tracer gas method recommended in BS 7258, 1994 : Part 4. Comparison of these two methods for testing fume cupboards 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 generation, 4) the disposition of equipment and 5) the sampling methods. It is demonstrated that the KI method is more sensitive than the gas method and that 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). |
