Safety is one of the most essential requirements of any laboratory and fume hood works for ensuring that vital safety factor of a lab. It purifies the air of the testing room by pulling out the toxic fumes and vapours from the room and even filtering back it in the room again. Thus fume hoods have key roles in protecting the lab personnel from consuming detrimental fumes of the lab environment and protecting their health.
To meet the required criteria of an acceptable laboratory fume hood. It must have the standard specifications that are internationally acclaimed.
The construction of the fume hood preferably would be of a picture frame airfoil design. Its construction will also be accordingly. It should have the efficiency to remove all kinds of fumes including heavy and light.
The standard food superstructure should be tested as per the ASHRAE 110-1995 test procedure and industrial hygienist’s recommendations.
Specification for materials
Metal—-Steel: It should be steel sheet of commercial quality with matte finish that complies with ASTM A 1008/A 1008/M. Also must be without scales and buckles
Stainless Steel: It should be of commercial grade type 304 or 316 of no 4 finish, ASTM A167 or ASTM A666.
Safety Glass: The required criteria for the safety glass are 1/4″ laminated for 400-foot-pound impact and to CPSC 16 CFR 1201. It needs to comply with ANSI 297.1.
PVC: Polyvinyl Chloride is recommended in extruded form.
Resin: Chemical resistant white polyresin or fibreglass reinforced thermostat resin with a flame-spread index rating of 25 or less is acceptable.
Specification for constructions:
The fume hood structure should have a double wall construction. The outer shell should consist of steel sheet and the inner liner would be of corrosion resistant specified material. On the other hand, the interior lining material to the steel framing should be of non-metallic fasteners. The double wall is for the purpose of concealing steel framing members and attaching brackets.
The side panels of the exterior part of the fume hood should be constructed of 18 gauge steel and it must be easily removable for access inside the interior portion. It should also ensure access into the interior liner. With the help of a PVC gasket the removable interior panels will be held in their positions.
There will be an internal baffle system of the material the same as the internal liner for each of the fume hood superstructure. When it will be connected to a properly installed exhaust, the baffle system should have the real efficiency of removal of fumes. There will be a manual adjustment system on the upper part of the baffle for the operator so that the mode for heavy or light fumes can be set.
The fume hood superstructure should be provided with an air bypass system other than it is specified for use in a verified air volume (VAV) system. This air bypass will be located at the upper part of the interior and its lower part will open as the sash in the lower part.