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Hood Types and Uses
Chemical fume hoods are approved for three general types of uses: General Purpose, Radioisotope, and Perchloric Acid. Hoods approved for each of these uses will appear alike but require different functional and operating parameters.
General purpose hoods, the most common use type, are used to prevent exposure to toxic, irritating, or noxious chemical vapors and gases. A face velocity of 100 feet per minute (fpm) provides efficient vapor capture while reducing hood turbulence.
Radioisotope hood systems are ideally made from welded stainless steel to ensure against absorption of radioactive materials. In order to comply with licensing requirements, iodinations using radioactive sodium iodide (I-125) must be performed in a hood with a minimum face velocity of 125 fpm. The certification label on the hood will indicate the hood is "Approved for Iodine-125" with a minimum face velocity of 125 fpm.
Perchloric acid hoods have wash-down capabilities to prevent the buildup of explosive perchlorate salts within the exhaust system. Researchers heating perchloric acid must use a perchloric acid hood. At this time there are no perchloric acid hoods at Clemson University. Please contact the Lab Safety Coordinator, Naomi Kelly, at 656-7554 if you have an experiment protocol that uses heated perchloric acid.
Hoods are checked annually by EHS and labeled for approved use. The arrow on the certification label indicates the proper sash position for constant volume hoods.
