You have chosen your fume hood for your new lab design – Kewaunee or Labconco – now don’t forget to consider the blower requirements. The size of the blower will depend not only upon the size of the hood but the length of the ducts and the path, eg., how many turns the duct-work takes before it exhausts outside. A measure of the duct static pressure will be useful in choosing the proper size blower motor. ANSI/AIHA Z9.5 American National Standard for Laboratory Ventilation guidelines recommends a face velocity of 80 to 120 feet per minute for fume hoods. ASHRAE* Standard 110-95 is a test which should be performed at the time of installation. This test determines whether the hood is functioning properly and whether it will protect the workers in the lab.
The type of blower also depends upon the chemicals used in the hood. Flammable chemicals require a fiberglass blower with an explosion proof motor. Perchloric acid hoods require a blower which can handle very corrosive atmospheres. These blowers have a PVC housing with PVDF impellers.
It may be the case that it is not possible to duct the hood to the outside. In this case a ductless enclosure may be the solution. These enclosures use a series special filters to remove the fumes and particles so that the air can be returned to the room.
Hood suppliers such as Kewaunee and Labconco have guides for choosing the correct fume hoods for your application.
*American Society of Heating, Refrigerating and Air-Conditioning Engineers