HVAC PRIME SOURCE, LLC
DAMPERS

General
There are several type of dampers used, depending on the required function.  The two broad functions are
flow control/isolation, and fire isolation (fire dampers). This sections discusses the flow control/isolation
dampers, while the fire dampers are discussed in detail in the NFPA standards.

Following are the major types of flow control/isolation dampers -

  • Multiblade dampers with opposed blades - used for small to large size applications for controlling or
    modulating air flow quantity. They are kept in partly open or full open/closed position depending on
    the air flow requirements.
  • Multiblade dampers with parallel blades - used for small to large size applications for air flow isolation.
    They are two position open or shut dampers.
  • Single blade or butterfly dampers - used for small to medium size applications for air flow isolation or air
    flow control/modulation.
  • Gravity operated backdraft dampers - used as a back flow preventer for small to medium size
    applications .

These dampers can be manually operated or provided with actuators for automatic operation. Following are
the various types of actuators that can be used -

  • Pneumatic (diaphram or piston type) - fail in open or closed position
  • Electric motor - fail as is (cannot provide fail open or closed position)
  • Electro hydraulic - fail in open or closed position

All of the above actuators can provide air flow isolation (open/shut) or flow control (modulation) function.
The variation is mainly in the power source and the capability of providing the desired fail position.