Fume Hood Exhaust Blowers

1. Blowers should be mounted on the roof in-order that the ducting leading to the blower inlet is under negative static pressure. If exhaust blowers are mounted inside the building, all ducting connected to the blower outlet will be under positive static pressure, if a leak were to develop in the section of the duct inside the building, toxic & or hazardous fumes could be forced out of the ductwork and into that area of the building.

2. To achieve the lowest practical noise level in the exhaust system, we suggest that the following measurements be used when there is no conflict with other specifications  of the system:

• Use vibration isolators or mounting blower exhaust assembly.

• Install a blower fan that will deliver the correct CFM and static pressure with the lowest practical impeller wheel RPM. 

• If possible, use a duct size large enough to keep duct velocity under 1800 FPM velocity.

• Use a flexible connection at the fan inlet to isolate mechanical transmission of noise from the ducting between the hood and the exhaust blower.

• Exhaust blower system should be designed with the fewest possible elbows or other fittings. Use radius type elbows & avoid using square elbows. Use gradual tapered transitions where necessary, & avoid abrupt changes in configuration or cross sectional area.

3. When ordering an exhaust blower, specify the orientation of discharge desired. Vertical up blast discharge is the most common and will be supplied unless otherwise specified.

4. All fans are shipped with clockwise rotation when viewed from the motor end of the assembly.

5. For normal usage, the standard for both the blower housing and impeller wheel is epoxy coated.

6. Blowers used for hood exhaust at altitudes above 1,000 feet, may require a correction factor to provide the correct CFM and static pressure.

Contact factory for details relating to your specific application.