Chemical Fume Hood Testing Procedures
- Position the sash fully raised.
- Puff smoke around the opening of the hood by using Ventilation Smoke Tubes (or other visible smoke device). All smoke should be captured by the hood exhaust and not be blown into the room.
- Position the sash so that the fume hood raised opening is 18-inches.
- Divide the fume hood opening into equal grids with sides measuring no more than 12-inches (approximately 6 grids).
- The tip of the Vane anemometer probe shall be positioned in the plane of the sash opening.
- Each grid velocity shall be the average of at least 10 measurements made over at least 10 seconds.
- Record each reading in the applicable square on the form.
- The average face velocity with the sash opening of 18-inches should be between 100-150 FPM. (An average face velocities greater than 150 FPM should be documented and reported to the Director of EH&S. If the average face velocity is less than 100 FPM lower the sash opening at I inch increments until 100 FPM is obtained. If an average face velocity of 100 FPM cannot be obtained at a sash opening of 12 inches the hood should fail the inspection.)
- Position the sash so that the fume hood raised opening is 6-inches.
- Divide the fume hood opening into equal grids with sides measuring no more than 12-inches (approximately 3 grids).
- Follow steps 4, 5 and 6 for measuring and recording.
- Fill out the required information on the “Laboratory Chemical Fume Hood Inspection” (Form ).
- If a Fume Hood does not pass, tape a “Warning Do Not Use/Out of Service” sign onto the sash, and remove or cross out any earlier inspection stickers. (Immediately notify the Director of EH&S)
- If a Fume Hood does pass, fill out an inspection sticker and affix it to the front of the hood. The metal sash frame, because of its visibility, is an ideal location for the sticker.
Determining Whether to Pass a Hood:
The following three conditions shall be met in order for a hood to pass:
- The average face velocity with the sash opening of 12 to 18-inches shall be at least 100 FPM.
- The average face velocity with the sash opening of 6-inches shall not be greater than 300 FPM.
- Smoke shall not escape the room during the smoke test.