iv
Chapter 5. Changing Capture Hoods ...................................................................................................... 43
Capture Hood Parts Identification ........................................................................................................ 43
Capture Hood Assembly ....................................................................................................................... 43
Alternate Hood Installation ............................................................................................................. 45
Direct Inflow Measurement Hood for Biological Safety Cabinets .................................................. 49
Chapter 6. Flow Measurements Using the Capture Hood .................................................................... 55
Single Reading Measurements ............................................................................................................ 55
Running Average Measurements ......................................................................................................... 56
Capture Hood Measurements (non-backpressure compensated) ....................................................... 56
Backpressure Compensated Measurements ....................................................................................... 56
................................................................................................................................. 57
Chapter 7. Maintenance and Troubleshooting ....................................................................................... 59
Fabric Hood .......................................................................................................................................... 59
Micromanometer ................................................................................................................................... 59
Manifold ................................................................................................................................................ 59
Cases ............................................................................................................................................. 59
Calibration ............................................................................................................................................. 59
Appendix A. Back Pressure ..................................................................................................................... 61
Verifying Flow Measurements .............................................................................................................. 61
Appendix B. Traversing a Duct to Determine Average Air Velocity or Volume.................................. 63
Where to Take the Measurement ......................................................................................................... 63
Traversing a Round Duct...................................................................................................................... 64
Traversing a Square Duct..................................................................................................................... 65
Appendix C. Swirl X Flow Conditioner for Airflow Instruments Model PH731
ProHood Capture Hood ............................................................................................................................ 67
Description ............................................................................................................................................ 67
Performance Data ................................................................................................................................ 68
Installation and Usage .......................................................................................................................... 69