Fume Hood Usage Guide: Standard Hoods

(Standard hoods do not have the “VAV control box” shown on the next page)

Per Cal-OSHA regulations, users of hoods must be trained on use of their fume hood. Attendance at one of the live or on-line lab safety orientations described below on the “UC Policy on Laboratory Safety Training” page satisfies that requirement. The information on this page should also be read by all hood users and is posted on campus hoods for easy reference.

Always work with the sash at, or below, the level of the red arrow sticker (picture on next pg.) and close it when not attended. To adequately protect you, your hood should be producing a face velocity of about 100 ft/min. EH&S tests your hood and posts the red arrow stickers at the proper sash level to:

  • satisfy the required air flow and protect you against airborne chemicals
  • protect you better from incidents within the hood
  • *All hoods on campus are equipped with an air flow monitor and/or alarm to warn you if the air velocity is too low – see examples pictured below. If the alarm engages, lower the sash slightly until the alarm stops. Do NOT disengage or over-ride the alarm. If your alarm sounds consistently this could indicate a real problem – call EH&S.
  • Always work at least 6 inches inside the hood to maximize capture efficiency.
  • Store only a minimum of equipment and chemicals in your hood because:
  • Excess materials will block the air flow into the intake slots at the back of the hood. Permanent equipment should be raised on a jack to allow the air to flow smoothly.
  • Most fires and explosions occur in the hood. Minimizing chemical volumes will reduce the chances of a small accident escalating into a large one.
  • Keep the lab windows closed. Drafts from open windows and doors can significantly affect your hood’s performance (100 ft/min is only a few miles/hr of air).


fume hood magnihelic gauge fume hood alarm
*“Magnihelic gauge” – note normal gauge position.
Significant deviation may indicate condition of low air flow.
*Visible/audible alarm
Sounds during low-flow