Policy, Scope and ApplicationResponsibilities; Employee Information;Employee Training; Student Training; Authorized Chemical Use;Control Measures, General Requirements;Specific Requirements; Protective Equipment; Fume HoodsExposure Monitoring; Medical Surveillance; Incidents; Waste Disposal; Chemical Exposure; Chemical Spills; Appendix

Fume Hood Operation 

Fume hoods are the first line of protection against exposure and over-exposure to hazardous chemical vapors and gases.  Chemical fume hoods are designed to operate at an optimum air velocity of approximately 100 linear feet per minute.  While it is good practice to work with the hood sash as low as possible, this measurement is made with the sash fully open to ensure protection at any sash height.

An air velocity of 80 to 100 linear feet per minute will result in a uniform air flow pattern which will capture most fumes and vapors likely to be given off within the hood.  Lower air velocities can lead to non-uniform air distribution patterns which will inhibit the efficient capture of fumes and vapors.  All hoods shall be inspected on a annual basis for proper flow by the facilities.  Such inspections shall be documented on supplied forms.

The following requirements apply to fume hood use.  Pertinent excerpts should be conveyed to all students at the start of the school year.

  1. Use the fume hood with the sash as low as possible, at or below the indicated operating height.  The operating height should be clearly marked by arrows on each side of the sash track.  If your hood does not have these arrows, contact facilities for recalibration of the hood and replacement of the arrows.  If you need to move large pieces of equipment into or out of the hood, raise the sash for as long as necessary and lower it as soon as possible.
  1. Do not experiment in the hood with the sash fully open.  The hood operates effectively with the sash at the operating height indicated by the arrows.  Additionally, this will allow the sash to serve as a physical protective barrier between your face and the contents of the hood.
  1. Do not store chemicals or chemical equipment not needed for the current activity or demonstration in the hood.
  1. Place large pieces of equipment up on blocks approximately 2 inches high to allow air to pass under the equipment.  This enables uniform air flow within the hood.
  1. Do not place equipment or chemicals very close to the slot openings in the baffles at the rear of the hood, or very close to the front edge of the hood as this will interfere with even airflow.
  1. Keep equipment and chemicals a minimum of 6 inches from the front edge of the hood at all times.
  1. Keep the sash glass clean, and never obstruct your view through it with paper, notices, decals or other items.
  1. Avoid sudden movement past the face of the hood when it is operating.  Walking briskly past the hood can disrupt air currents and pull vapors out of the hood.
  1. Keep your head outside of the fume hood.
  1. If your hood is equipped with a flow indicating device, check to see that it is operating properly before use.  If your hood is not equipped with such a device, you can qualitatively check it by using a small piece of tissue or Kimwipe┬«.  Hang the tissue at the bottom of the hood sash.  It should be drawn in when the hood is operating properly and will hang straight down if the unit is not functioning.
  1. Never use an improperly functioning hood.  If your hood is not functioning properly, check to make sure it is on and that the rear slots are not blocked or closed.  If this is not the problem, contact facilities to have the unit repaired.  Instructors are required to qualitatively check their hood for proper operation as indicated on the quarterly inspection form.