Page 274 - FanPedia - By Twin City Fan and Blower

FAN-PEDIA

Published by TECHNICAL DESCRIPTIONS

Twin City Fan & Blower

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Companion Flanges (Round and Rectangular)
Companion flanges are connected to the connecting ductwork in the field and ensure a matching
connection to the fan. They are shipped loose for field mounting.

Damper: Butterfly Damper
Back Draft dampers are commonly installed in fan exhaust systems to prevent a back draft of outside
air when the fan is off. The damper is either a Spring Return type for both horizontal and vertical
mounting or Gravity Return used in vertical venting only.

Damper: Gravity Damper (Wall Type)
Wall Type Gravity Dampers are designed to open automatically when the fan is energized and to close
by gravity when power is turned off, these parallel blade, end pivoted dampers provide a mechanism
which prevents the air from back flowing through the system while also serving to exclude outside
elements such as rain and snow.

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