- Stairwell Pressurisation Fan ("SPF")
A stairwell pressurisation fan is an electromechanical assembly that comprises an electrical motor and fan unit that draws fresh air from outside of a building to pressurise a stairwell. The combination of positive air-pressure within the stairwell along with fresh air from outside helps provide for the safe exit of the occupants from a building.
Under normal circumstances, a stairwell pressurisation fan is not used and the fan remains de energized (or not operating). In fire mode, a stairwell pressurisation fan receives a signal from the fire detection and alarm system to energise (activate) the electric motor of the fan assembly.
Typically on the inlet or suction (outside air) point of the fan a smoke detector is fitted. This smoke detector is used to detect the presence of airborne contamination (smoke) coming from the outside air, entering into the stairwell.
When this detector is activated (alarm) it signals the fan to temporarily stop until the detector returns to its normal (non-alarm) state.
When the detector returns to its normal non-alarm) state, the fan receives a signal from the FDCIE to energise (activate), and continue to pressurise the stairwell with fresh air.
This cycle will repeat until the cause of the original building alarm signal is identified and reset.
- A smoke detector connected to a stairwell pressurisation fan does not typically send a signal to the alarm monitoring company and in-turn the fire brigade, i.e. its is a local alarm only signal.