The Potassium Iodide Method for Determining Protection Factors in Open-fronted Microbiological Safety Cabinets

A method for determining operator protection factors in Class I and Class II microbiological safety cabinets and for evaluating product protection factors in Class II cabinets, is described. The technique employs an aerosol of potassium iodide droplets produced by a spinning disc generator together with special centripetal air samplers detecting any aerosol escape. The method meets the requirements of British Standard (BS) 5726 and is an alternative to the microbiological technique.
The method has been used to evaluate the performance of a number of safety cabinets in relation to the requirements of BS 5726.
Working procedures and unsuitable environments have been shown to prejudice the containment performance of open-fronted cabinets by several orders of magnitude.
The relationship between inflow air velocity and protection factors in Class I safety cabinets has confirmed the optimum requirements defined in the British Standard.