Backdraft
Dampers
Backdraft Damper Training
Application
Backdraft dampers allow air to flow in one direction only
and prevent unwanted (hot/cold outside air, wind, etc.) from
“back-drafting” into the building.
They only install in ducts, at walls, or in roofs and open
automatically when air flows in the intended direction and
automatically close when there is no air pressure or when
airflow is in the opposite direction.
Basic Functions
• Intake/Exhaust
• Barometric/Pressure Relief
Backdraft Damper Training
Intake
Intake backdraft dampers allow supply airflow into a building
while preventing conditioned air from escaping when the fan
is off.
Typical Applications
• Intake Air Duct - Wall or plenum mounted
• Intake side of rooftop evaporative cooler
(requires counterbalance)
Backdraft Damper Training
Exhaust
Exhaust backdraft dampers allow air to automatically exit the
building and prevent outside air from entering the building.
Typical Applications
• In tandem with wall mounted exhaust fan.
• Exhaust air duct - wall or plenum mounted
• Roof top power ventilator • Rooftop gravity ventilator
Backdraft Damper
Backdraft
Damper
Roof Top Power Ventilator
Wall Mounted Exhaust Fan
Backdraft Damper Training
Barometric
Barometric relief dampers open automatically under low velocity
conditions - including natural airflow - and close automatically to
prevent reverse airflow.
Backdraft
Damper
Typical Applications
• Rooftop gravity ventilator
• Wall mounted relief
(no duct or fan)
Roof Top Gravity Ventilator
Backdraft Damper Training
Pressure Relief
Pressure relief dampers use counterbalance weights to
maintain a relatively constant upstream pressure, they open
automatically at higher pressures and close automatically
when pressures drop.
Typical Applications
• Duct or plenum relief
• Room relief
Backdraft Damper Training
AMCA 500D Test
Requirements
Test Samples
• Pressure drop: 12x12, 12x48, 48x12, 24x24, 36x36
Pressure Drop
• Ducted Inlet and Outlet - AMCA 5.3
Lowest Pressure Drop
• Ducted Inlet Only - AMCA 5.2
• Plenum Mount - AMCA 5.5
(Highest Pressure Drop)
AMCA 5.3 – Ducted Inlet & Outlet
AMCA 5.2
Ducted Inlet
AMCA 5.5 –
Plenum Mount
Backdraft Damper Training
Design Basics and
Typical Application
Light Duty
• Most common type and widely used for intake, exhaust,
barometric, and pressure relief applications where air
pressures and velocities are low (≤ 2 in wg. & 1250 fpm).
Medium Duty
• Typically used for intake, exhaust, and pressure relief when
pressure or velocity exceeds the light duty range (>2 in wg.
& 1250 fpm, but ≤3 in. wg. And 2500 fpm.
Industrial
• Employed when the temperature, pressure, or velocity
exceed standard commercial damper limits. Units are
typically flange mounted directly to the duct or fan housing.
Backdraft Damper Training
Light Duty Backdraft Dampers
Applications
– BD-50
• Gravity Intake and Exhaust • Prop-Fan Exhaust • Roof Top Power Ventilator
– BD-51
• Intake or Exhaust – where damper blade noise is a concern
– BD-52
• Evaporative Cooler – Discharge Side (down-flow only)
– BD-54
• Pressure Relief
Adjustable
Counterbalance
Weight
Mounting Arrangements
– Vertical Mount
– Horizontal Mount
• Up-flow
• Down-flow (BD-52 Only)
Caution
– Multiple Sections
– Maximum Velocity &
Channel Frame
Pressure Limits
– No Exact Pressure Settings
Vertical Mount
Horizontal Mount
Tie-Bar
Integral
Counterbalance
Weight
Backdraft Damper Training
Medium Duty Backdraft Dampers
Applications
Concealed
Linkage
– BD-60
• Fan Exhaust - Duct or Plenum Mount
– BD-64
• Pressure Relief - Higher velocity
Adjustable
Counterbalance
Weight
Mounting Arrangements
– Vertical Mount
– Horizontal Mount
• Up-flow only
Caution
Vertical Mount
– Low-end velocity and
pressure limits
– No Exact Pressure Settings
– Retarding Counterbalance
Design Only - No assist to Open
Hat-Channel
Frame
Horizontal Mount
Backdraft Damper Training
Industrial Backdraft Dampers
Applications
– BD-84
Channel Frame
Concealed
Linkage
• Fan Exhaust - duct or plenum mount
Mounting Arrangements
– Vertical Mount only
Caution
– Low-end velocity and
pressure limits
– No Exact Pressure Settings
– Assist to Open Counterbalance
design only
Adjustable
Counterbalance
Weight
Backdraft Damper Training
Options &
Accessories
Flange Frame
• For flush mounting to equipment/wall
• Intake or discharge
Sleeve
304 Stainless Steel Construction
Electric Actuator (BD-58 Only)
Backdraft Damper Training
THANK YOU!