Views: 0 Author: Site Editor Publish Time: 2022-06-29 Origin: Site
1. General Purpose of lab fume hood
The level of protection provided by a fume hood is affected by the manner in which it is used. No fume hood, however well designed, can provide adequate containment unless good laboratory practices are used. Adequate planning and preparation is the key. The hood user should know the Standard Operating Procedures (SOP) of the hood and should design experiments so that the SOP can be maintained whenever hazardous materials might be released.
Items contaminated with odorous or hazardous materials should be removed from the hood only after decontamination of it, if placed in a closed outer container, to avoid releasing contaminants into the laboratory air. The following work practices are to be followed when hazardous materials, equipment and operations are being used inside laboratory fume hoods.
2. Correct work practices and procedures
M—Monitor. Check the airflow monitor before commencing to ensure that the fume hood is working correctly. Laboratory fume hoods come with monitors or devices whose function is to provide the user of the hood with important information concerning airflow & face velocity. Monitors will alarm and alert the user when there is a problem with the airflow or face velocity. For a typical fume hood, the optimum face velocity is no less than 100 feet per minute (fpm). In the case of low-flow, high-efficiency fume hoods, the acceptable face velocity is 80 fpm. (NOTE: Document all alarm events for low-flow, high-efficiency fume hoods. Include the date and time of occurrence, as well as the cause of the alarm event.)
O-Operational. Check the other fume hood components (sash, lights, baffles) to make sure that these items are operational. Do not remove the fume hood sashes or panels except when it is necessary to set-up apparatus; they must be replaced before any operations begin. All chemical hoods should have spill protection lips along the front of the hood. If your hood has a cup sink, it should have a lip as well.
P-Placement. Place apparatus a minimum of six inches back from the face of the hood. Do not store excessive amounts of chemicals or apparatus in the hood since these items can greatly impair fume hood performance. Do not obstruct the slots of the baffles along the back of the hood. No more than 25% of the bottom slot should be blocked. All large equipment should be elevated 1-2 inches above the working surface of the hood to reduce the amount of baffle blockage and to maintain the hood’s performance. If there is a chance of explosion or eruption, use an appropriate barricade or shield. Do not place your head inside the hood when contaminants are being generated.
S-Sash Height. Adjust the sash height to the operating height or lower. The operating height is indicated by an arrow on the yellow/gold/green (see example to the right) decal affixed to the front side of the hood. When the sash is placed at the proper operating height, it will also provide a barrier against unanticipated explosions, fires, spills, or splashes, and conserve energy. Report fume hood repair issues to Facilities Management immediately. Remember to close the sash when not in use. It costs approximately $3K a year to operate a fume hood due to the energy expended to move the vast volume of air. Closing the sash helps minimize the volume and therefore affect the operating cost of the fume hood.
