Fume Hood Configurations

The atomic absorption unit should not be operated without proper supervision. Operate according to instructions and use special caution with flame and in handling acetylene. Be sure the fume hood over the instrument is on and the drain line is properly configured. 

The most popular sash configuration is the vertically sliding type. The sash must be counter weighted, especially if the sash window is made of heavy glass. In order to avoid a guillotine effect should the counterweight cable break, a safety device must be incorporated in the sash. As for transparent materials used for the sash window, only a few are used in good quality, currently available commercial fume hood models. 

There are a variety of slot type exhausts, configured much like the common vacuum cleaner crevice tool. Again to be effective, the fume source must be quite close to the exhaust device In any event, the use of a localized exhaust, if used properly, wiU be much more energy efficient than a fume hood. 

Drum dryer, double drum, (conduction) atmospheric pressure, cast iron, chrome plated with 304 s/s side and cross conveyors, dip pan, knife assembly, rotary steam/water joints, end scrapers, drive, motor and fume hood. FOB cost 210000 at total drum area = 9 m with n = 0.52 for the range 0.9-40 m. L+M = 2.6-2.75. L/M = 0.3-0.36. Alloy factors cast iron chrome-plated, X 1.0 c/s, X 0.9. Factors drum configuration double drum, X 1.0 single drum, X 0.9 twin drum, X 1.0. 

Scrubber units are typically configured vertically and are located next to the fume hood as shown in Figure 8.7. They are also produced in a top mount version, in which the packing, spray manifold, and mist eliminator sections are located on top of the hood and the sump and liquid handling portion are underneath the hood for a compact arrangement taking up no more floor area than the hood itself. 

With aU the variation allowed by all of these configurations, the room air supply system must be so designed as to maintain the room air balance, no matter what sash arrangement is used, or for that matter, whether the hoods are in operation or not. The hoods and HVAC systems need to be interlocked to ensure this. In addition, if the HVAC system should fail, the hoods need to be equipped with an alarm to alert users of the failure. The hoods in such a case should be shut down if this not done automatically and the sashes closed to prevent fumes from escaping into the laboratory. In newly built facdities, especially larger ones, the HVAC systems are managed by a computer system to ensure the room air balance is maintained at all times, and so designed as to provide an alarm should the air velocity fall below the specified value in the exhaust ducts. 

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