How do you connect the fire damper to the smoke exhaust fan control circuit?
Put the normally-closed limit-switch contact at the 280°C fire damper handle in series with the smoke exhaust fan control circuit. When the damper acts, the contact opens, the circuit breaks and the fan stops at once. Six such dampers are wired in series; if any one acts, the fan stops.
1. Supply outlet and positive-pressure fan linkage: on a fire, the detector alarms, the fire alarm controller accepts it, a module auto-opens the pressurisation supply outlet and the pressurisation fan, and feeds status back to the controller and the control centre.
2. Ways to stop the positive-pressure fan:
a. The 280°C supply outlet fuse closes, the controller stops the fan via a module. b. The 280°C supply outlet fuse closes, the fan stops. c. The control centre stops the fan manually. All three feed status back to the controller and the control centre.
3. The direct outlet-fan link shows up as stopping the fan on close. The start signal for the positive-pressure or smoke fan comes from the controller after the detector alarms, then a module stops the fan. The outlet opening also comes from the controller after the detector alarms, then a module opens it automatically. The linkage is parallel, not direct: the open outlet gives the fan a physical path for supply or extraction.
How does the fire damper work?
The smoke fire damper is a fire component on the mechanical smoke extraction duct. Main materials: carbon steel, galvanised sheet, stainless steel. In a fire, when the temperature reaches 70°C it closes and within a set time meets the leakage and fire-resistance integrity requirements, blocking smoke and fire. Daily upkeep of the damper also matters.
1. Do not store the smoke fire damper in a damp place, or over time it will rust, lose weld and short-circuit.
2. Do not expose it to wind, rain or direct sun, or the mechanism may fail.
The smoke fire damper needs inspection and upkeep every six months: clean surface dust and dirt, tighten the spindle and mounting screws, check the electromagnet, micro-switch and wiring for damage, ageing or failure, and check the brake and limiter against specification.
Repair any defect at once. Grease the moving parts, then re-energise and test so there is no abnormal behaviour.
3. Fire damper: on supply and return ducts of ventilation and air-conditioning systems. Normally open. On a fire, when the duct gas reaches 70°C it closes and meets fire-resistance stability and integrity, blocking smoke and fire.
4. Smoke fire damper: on smoke ducts. Normally open. On a fire, when the duct gas reaches 280°C it closes and meets the same requirements.
Principle:
The fire damper fits in the central air-conditioning duct system. It works by thermal fuse control, using gravity and a spring to close. On a fire, flame enters the duct, the high temperature melts the fusible alloy or deforms a memory alloy, and the valve closes automatically. Used where the duct passes a fire compartment.
1. Fire damper or control fire damper: normally open, closes at 70°C. Usually at the firewall crossing. Can output a signal; at smoke over 70°C the valve closes and interlocks the supply (make-up) fan to stop.
2. Smoke-fire control damper: normally open, closes at 70°C, same as above but with an extra electrical input so it can be closed remotely from the control centre. Used in shared supply and fire-make-up ducts to close rooms that need no make-up on a fire.
3. Fire damper, 280°C fuse close, normally open, outputs a signal. Like item 1 but a different fuse temperature. Used where a smoke duct crosses a firewall; at smoke over 280°C it fuses shut automatically and interlocks the smoke fan to stop.