Protection Against Vapors and Gases
All Class II biosafety cabinets are required to provide personnel, product and environment protection from particulate contaminants. There has been increased attention given to personnel and environmental protection from non-microbial chemicals, vapors and gases.
Distinctions between Type A1 and A2 and B1 and B2 cabinets are most dramatic when all types are subjected to tests for the presence of chemical vapors.
Toluene Vapor Test Illustrates Differences
The chart on the right shows the location of toluene vapor generator (inches from front of work surface) in the Type A and Type B (total exhaust) cabinet.
In an effort to provide quantitative information about performance differences among the three Class II cabinet types, the Baker research laboratory has tested each cabinet with toluene vapor. Tests were conducted under strict experimental conditions using vapor concentrations higher than found in typical practice. All cabinets were vented to the outside.
The performance of different Class II cabinets is distinctly different when considering filtration, ventilation, air exchange, and airflow.
Test Result Summary
Toluene vapor test results illustrate distinctly different vapor return patterns for each cabinet type
|Cabinet Type||Test Result|
|Type A Cabinet||Vapor concentrations in the downflow air reached a constant value which did not significantly change as the vapor generator was moved from front to rear of the work surface.|
|Type B1 Cabinet||Significant changes occurred as the vapor generator was moved from front to rear of the work surface. With the generator placed in front, the amount of returned vapor paralleled the performance of the Type A cabinet. With the generator placed in the rear, returned vapor paralleled performance of the 100% total exhaust cabinet (Class II, Type B2). The downward curve illustrates the variance in vapor concentration related to location from front to rear.|
|Type B2 Cabinet||In the 100% total exhaust cabinet, no air is recirculated and all vapor was removed.|
|Type A2 Cabinet||Vapor concentrations in the downflow air reached a constant value which did not significantly change as the vapor generator was moved from front to rear of the work surface.|
A detailed report, Comparison of Chemical Vapor Handling By Three Types of Class II Biological Safety Cabinets, is available from The Baker Company. Please contact us to request a copy.
The Baker Company has prepared a mathematical formula for determining the amount of vapor that would be recirculated under a particular application using other volatile chemicals. For a free copy contact The Baker Company.