Fume hoods are tested annually (or following any adjustment to the ventilation system) to confirm the fume hood is operating as intended. Testing includes the following;
- Visual inspection of the fume hood that includes general condition and sash and baffle function
- Fume hood performance testing through face velocity measurements and airflow visualization using a smoke test
- Fume hood monitor performance
- Fume hood testing certification stickers
1. VISUAL INSPECTION OF FUME HOODS
Visual inspections of fume hoods include the following criteria:
- Sash operation to ensure free movement within track with no binding and stable enough to remain at set height.
- Sash meets generally accepted safety standards.
- Constructed of transparent, shatterproof material.
- Sashes are movable and free from physical defect.
- Sash stops are installed/verified so as to prevent rising beyond maximum sash opening area, or, safe operating height as noted with the use of certification stickers.
- A general fume hood condition inspection to record any corrosion, fouling, or other condition which would impact the safety of users.
2. FUME HOOD PERFORMANCE TESTING
Testing the performance of the fume hood involves completing the following tests: an airflow visualization test, a face velocity test, and a response test for all variable air volume (VAV) systems.
- Airflow visualization tests as outlined by ANSI/ASHRAE 110-1995: Methods of testing Performance of Laboratory Fume Hoods and ANSI/AIHA Z9.5-2012: Laboratory Ventilation.
- No visible escape beyond the plane of the sash when placed 6 inches into the hood.
- Smoke generation to be used to identify areas of reverse flow, stagnation zones, vortex regions, escape and clearance.
- Dynamic challenges should also be tested by moving the sash up and down during the smoke test.
- Face velocity tests as outlined by ANSI/ASHRAE 110-1995: Methods of testing Performance of Laboratory Fume Hoods and ANSI/AIHA Z9.5-2012: Laboratory Ventilation.
- All face velocities to be collected when sash height is at standard worker operating height of 18 inches.
- A passing velocity is between 80 FPM and 150 FPM at a sash height of 18 inches. An average of 100 FPM is an ideal velocity for fume hoods in a laboratory.
- Variable Air Volume (VAV) system verification testing. A response and stability test for all VAV hoods are to be completed as outlined in ANSI/AIHA Z9.5-2012: Laboratory Ventilation.
- A response test to confirm sufficient increase or decrease of air flow to allow the air velocity to be maintained.
- A stabilization test to confirm appropriate flow rate with an appropriate response time after the completion of the sash movement.
3. FUME HOOD MONITOR PERFORMANCE
Fume hood monitors are calibrated based on annual face velocity readings with high and low alarms set based on the readings collected.
4. FUME HOOD TESTING CERTIFICATION STICKERS
Annually fume hood performance verification stickers are applied to all fume hoods. Each sticker identifies the unit being tested, the testing methodology completed, the average face velocity recorded at the operating height of 18 inches, date of the testing and the name of the person completing the test.
If a fume hood fails the test, EHS is notified and the unit is tagged out with a Notice of Failure sign. EHS notifies the owner of the space and coordinates the repair with Facilities Management and Planning.
Contact EHS if the fume hood in your lab has not been tested within the last year, or if you feel that the fume hood is not operating properly due to one of the following reasons:
- An adjustment has been made to the fume hood.
- If the fume hood has become inoperable for more than 24 hours.
- Other indications that the unit may not be operating properly.