[AC] 問﹕Fume Cupboard Design 有啲乜要留意？

A.      Function of fume cupboard

-    To  remove  fumes  effectively  so  as  to  keep  the concentration of the contaminants  in the breathing zone of the operator to below the exposure  limits  and  also  to  prevent  the  build up of an explosive atmosphere inside the FC.

-    To place a physical barrier between users in the laboratory and the work inside the fume cupboard.

-    To provide an effective containment device and exhaust in case of accidental spills and emergency.

B.      Type of fume cupboard

-   Conventional fume cupboard

-    CAV (Constant air volume- when sash is lowered down, high face velocity ie Q=VA, turbulence occur, bypass with modulating valve should be added

-    VAV air volume, the exhaust air is controlled to maintain face velocity in preset value when the ash is partially closed.

-    Auxiliary air fume cupboards- same as conventional fume but add dedicated makeup, reduce energy loss of return air taken by fume cupboard. Exhaust venturi valve interlock with make up air to maintain negative pressure for the fume cupboard.

-    Re-circulatory or ductless fume cupboard- no direct exhaust to open air, independent exhaust and re-circulate by filter

-   Water supply point with drain

C.      Design checkpoint

-    Location: away from normal traffic pattern, cross-draughts, air inlets and other sources of disturbance, exit from a work space (may have potential risk of fire or explosion in fume cupboard)

-    Face velocity = 0.5m/s

(鳴謝﹕紅豆)