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BMBL Appendix A - Table1
Comparison of Biological Safety Cabinets
| Type |
Face velocity (lfpm) |
Airflow Pattern |
Radionuclides/
Toxic Chemicals |
Biosafety Level(s) |
Product Protection |
| Class I* open front |
75 |
In at front; rear and top through HEPA filter |
No |
2,3 |
No |
| Class II Type A |
75 |
70% recirculated through HEPA; exhaust through
HEPA |
No |
2,3 |
Yes |
| Type B1 |
100 |
30% recirculated through HEPA; exhaust via HEPA
and hard ducted |
Yes (Low levels/volatility) |
2,3 |
Yes |
| Type B2 |
100 |
No recirculation; total exhaust via HEPA and
hard ducted |
Yes |
2,3 |
Yes |
| Type B3 |
100 |
Same as IIA, but plena under negative pressure
to room and exhaust air is ducted |
Yes |
2,3 |
Yes |
| Class III |
NA |
Supply air inlets and exhaust through 2 HEPA
filters |
Yes |
3,4 |
Yes |
* Glove panels may be added and will increase face velocity
to 150 lfpm; gloves may be added with an inlet air pressure release that will allow work
with chemicals/radionuclides.
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