How to Select and Use Air Dampers

In exhaust and ventilation design, correct damper selection is essential. Many damper types exist, so designers must know categories and functions. CHINENG shares how to select and use them.

(1) Damper types and functions

Common dampers in kitchen exhaust systems include:

1. Multi-leaf dampers: most common—simple, easy to install, good regulation. Parallel or opposed blades; standard or sealed; electric, pneumatic, or manual control of 0–90° blade angle for volume or on/off.

2. Butterfly dampers: a disc rotates on a shaft for shut-off or throttling—simple and easy to control, mainly manual or electric.

3. Check dampers: allow one-way flow to stop grease or cold-air backdraft. Butterfly, multi-leaf, automatic louvers, and duct valves can serve this role by design.

4. Sealed inclined slide gates: an angled gate reduces resistance versus a straight gate; hood balancing plates are a simple slide form.

5. Fire dampers: usually at hood–duct connections, normally open; at about 280°C the fusible link melts, the damper closes, and the fan interlocks off to stop fire spread in ducts.

6. Weather louvers: fixed, gravity, manual, or motorized; drain-channel blades keep rain from forming a water curtain across the opening.

7. Pressure relief dampers: maintain room positive pressure without power by balancing damper weight against static pressure.

8. Constant-volume dampers: self-acting mechanical devices that hold set airflow across a pressure range—rarely used in grease exhaust.

9. Three-way valves: for precise diversion/mixing of fluids or steam—rarely used in exhaust systems.

(2) Selection tips

1. Weather louvers: at indoor/outdoor boundaries. Avoid on greasy ducts—oil fouls blades and raises resistance; enlarge free area to offset louver pressure drop.

2. Fire dampers: required on grease-laden ducts.

3. On/off dampers: butterfly, check, or multi-leaf dampers isolate branches when one fan serves multiple time-shared ducts.

4. Volume dampers: when one fan serves multiple ducts, throttle low-resistance branches with multi-leaf, slide, or butterfly dampers to balance airflow.

In summary: correct damper selection protects system performance. Follow the CHINENG website for more updates, or contact online technical support for commercial kitchen equipment advice.