STAIRWELL PRESSURIZATION SYSTEM
SCOPE OF THE INVENTION
The present invention relates to a stairwell pressurization system, and more particularly an inexpensive and easily installed system which is adapted to produce a positive pressure of firesh air in a high-rise building stairwell in the event of a fire.
BACKGROUND OF THE PRESENT INVENTION
In Canadian residential apartment buildings, fire code regulations in most regions stipulate that in the event of a fire alarm, residents are to stay inside their individual dwellings or apartment units, and ought not walk down stairwells, use elevators, or travel along hallways or in other common areas.
The issue becomes what happens to individuals who are in a hallway, common area, or stairwell when a fire alarm is first initialized and smoke is originating from lower floor areas.
There is also the possibility that certain individuals might suffer from fire induced panic attack or that the brightly lighted sign reading "EXIT" placed beside each door leading toward the stairs might mislead them to enter the stairwell. In such case, people will run toward the stairs and attempt exiting the building by going down the stairs toward the main floor and safety. But the stairwell is full of smoke and, maybe, fire has already reached that particular floor. They have nowhere to run and may risk suffocating in the stairwell rather than going back toward the fire.
It has happened before and people have died on the stairways because it had been their only option to escape the fire.

SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a smoke Free Stairway System which eliminates or at least greatly reduces the risk of suffocating in high-rise stairwells in the event of a fire. The Smoke Free Stairway System will reduce this risk by maintaining firesh air inside the stairways. The system is adopted to produce a positive pressure of substantially smoke free air in the stairwell and thereby prevent the infiltration of smoke in the stairwell, allowing people to safely exit the building.
A stairwell pressurization system is interconnected to a fire alarm for simultaneous operation. As a result, when the fire alarm system is sounding, the pressurization system is used to create a positive pressure in the stairwell and prevent smoke or substantially reduce any smoke penetration into the stairways. The system includes one or more fans which are operated at the same time as the existing fire alarm system. The operation of the fans forces smoke free air from outside the building into the top and bottom of each stairwell. This creates a positive air pressure in the stairwell, which prevents the movements of smoke from the building hallways and common areas into the stairwells, creating a safe area for individuals to exit the building. The system maybe further configured to turn off any secondary roof top ventilation system which provides airflow to the building hallways or common areas. This advantageously reduces pressure from the common and hallway areas, resulting in enhanced airflow from the pressurized stairwells into the hallways. In case of stairwell exit doors being opened simultaneously, pressure sensors in the stairwells are used to sense a pressure drop. Upon sensing a pressure drop, the sensors are used to provide control signals to the fans to operate at increased power and speed until the pressure in the stairwell is returned to a desired level.

2 Even though firefighters are wearing oxygen masks, it is difficult and time consuming to penetrate the smoke in the stairwell while going up the stairs toward the fire affected area. If the stairwell would be smoke free, the firefighters could save precious time to reach their destination and save more lives and material goods from destruction. Time is a critical issue when dealing v~rith fire, and the Smoke Free Stairway System gives people more time to reach safety while at the same time reducing the time that the firefighters will need to get to the fire and extinguish it.
BRIEF DESCRIPTION OF THE DRAWINGS
Reference may be had to the following detailed description of the preferred embodiments taken together with the accompanying drawings, in which:
Figure 1 shows schematically, a high-rise construction incorporating a stairwell pressurized system in accordance with the a first embodiment of the invention;
Figure 2 shows a perspective schematic view of a stairwell pressurization system in accordance with second embodiment of the invention;
Figure 3 illustrates an enlarged detailed view of the system shown in Figure 2; and Figure 4 illustrates a sectional view of the system shown in Figures 2 and 3 in the occurrence of a fire.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Reference is first made to Figure 1 which illustrates a stairwell pressurization system 100 for use in providing a substantially smoke free stairwell 102, in the event of a fire. The system 100 consists of at least one or more fan systems 1 which are operable to force fresh air from outside the high-rise building into the stairwell 102. A fan system 1 may lead directly into either a. lower portion of the stairwell as for example, is shown in Figure 1, or alternately at multiple locations as shown in Figures 2 to 4, wherein two fan systems are provided on both the main floor and roof of the building to force air into upper and lower portions of the stairwell 102.
Furthermore, in the pressurization system 100 shown in the Figures, the following elements are present for systems used in a, commercial or residential high-rise building.
1. Fan systems located on the roof of the building.
2. Feeding area of the fans from the roof.

3. Smoke detector switch.

4. Pressure sensors (one for each floor) switch.

5. Two systems located on the main floor or in the basement.

6. Two fire-doors system between the exteriors of the buildings and the emergency stairway. The fire doors should be installed 7 - 10 feet apart (distance between the doors) in order to form a cushion room that has the role of maintaining the pressure in the stairwell at a constant level during the emergency evacuation. Preferably, the two doors are provided with a block-up type system that permits only one of the two doors to be opened while the other one remains closed. The two doors will never be opened both at the same time.

7. Stack extension attachment to the ventilation system - prevents the smoke combination of the fans located on the roof of the building.

8. Exhaust fans from the (existing) ventilation systems in the hallways.

9. Entrance doors into apartment units.

10. Ventilation system outlet in the hallway.

11. *Fire scenario (show in Figure 4) shows the smoke movement from the common hallway areas.

12, 13, 14. Show the pressure level in the stairwell, hallway and apartment unit.
The present invention provides a smoke free stairwell system, which substantially reduces or eliminates the concern of individuals asphyxiating in stairwells and common areas as a. result of smoke inhalation. More particularly, it is proposed to develop an economical stairwell pressurization system 100 which may be installed in either new or existing constructions, and vvhich is configured to reduce smoke penetration into emergency stairwell areas. For efficient smoke protection, the air pressure in the stairwell should be higher, and preferably at least 1.1, and more preferably upto at least 1.5 times the pressure in the hallways and/or atmospheric pressure, and which in turn should be higher than the air pressure inside the individual a.partments/units.
The pressurization system 100 is adapted to operate in conjunction with a conventional fire alarm or an existing system, and includes as its principal components:
~ In the case of a low-rise building (3-7 stories) ~ two variable speed fans located in the basement or on the main floor ~ motorized door on the first floor of the emergency stairwell ~ cushion room ~ pressure sensors ~ In the case of a medium-size building (1-16 stories) ~ four variable speed fans (two of them located in the roof for system 1 of the building and the other two in the basement or in the main floor fan system 1 ) ~ pressure sensors 4 (double the number compared to the low-rise building) D smoke detector switch 3 for the fans located on the roof of the building;
this detector has the function to turn off the fans 1 located on the roof if smoke from the exterior of the building is arriving in the feeding area 2 of the fans exhaust attachment or stack 7 (10-12 feet) for the existing roof top ventilation system; its function is to prevent the outside smoke to reach the feeding fans area motorized door located on the first floor cushion room 6.
cushion room ~ In the case of a high-rise building (150-1,000+ feet) ~ all the elements presented for the medium-size building, plus ~ air distribution system The cushion room 6 is located on the first floor and is connected to the emergency stairwell at the front end and with the exterior of the building at the back end. This room has most preferably two doors located in such a way as to leave 7-10 feet distance between them.
'fhe cushion room is necessary to maintain the permanent positive pressure in the stairwell. It can also facilitate an easy exit from the stairway toward the exterior of the building. The cushion room will thus prevent the drop off pressure on the stairwell. The walls of the cushion room will not affect the structure of the building, being built of light brick or other type of material.
Preferably, the fans 1 are located in both the roof and basement areas of the building, and are operable to force exterior air simultaneously into upper and lower portions of the stairwell I 02.

Ductwork 106 (Figure 4) preferably also extends vertically from the stairwell 102 from areas adjacent to each fan system 1. The ductwork 106 is provided as part of an air distribution system and for example, could have a series of successively larger openings providing airflow into the stairwell as one moves further from the fan systems 1.
The air distribution system and ductwork106 is adapted to facilitate movement of smoke free air from the various points vertically therefrom. In this regard, the ductwork, could, in a simplified construction, consist of a sheet metal pipe or duct, which is provided with a series of progressively larger openings. The pipe is provided extending vertically along the stairwell with progressively larger openings spaced further from the fans' source. One or more of the pressure sensors are provided at vertically spaced locations along the stairway. In a basic configuration, the duct system is merely open to a lower portion of a stairwell, however, in an alternate configuration; the ductwork is coupled directly to one or more of the fan motors.
i;) Standby Operation In a standby operation, the fans would be maintained in an off position to conserve energy.
ii) Activated System In the event of a fire (as shown in Figure 4), both the fire alarm system and the stairwell pressurization system 106 are interconnected for simultaneous operation. As a result, when the fire alarm system is sounding, the pressurization system is used to prevent smoke or substantially reduce any smoke penetration into the stairways.
In the event of a fire, both fans 1 are operated at the same time as the existing fire alarm system. 'The operation of the fans forces smoke free air from outside the building into the top and bottom of each stairwell 102. This creates a positive air pressure in the stairwell, which prevents the movement of smoke from the building hallways and common areas into the stairwells, creating a safe area for individuals to exit the building.
Preferably, the fans 1 are operable to maintain the stairwell pressure at about 1.2 to 3 times higher than normal atmosphere pressure. The system maybe further configured to turn off any secondary roof top ventilation system 8 which provides airflow to the building hallways or common areas. This advantageously reduces pressure from the common and hallway areas, resulting in enhanced airflow from the pressurized stairwells into the hallways.
In the case of several stairwell exit doors being opened simultaneously, the pressure sensors in the stairwells are used to sense a pressure drop. Upon sensing a pressure drop, the sensors are used to provide a signal to the fans to operate at increased power and speed until the stairwell pressure is returned to a pre-determined threshold. In this manner, the fans are used to maintain a simultaneously consistent positive pressure in the stairwells.
* Related to 11 - As such, if in one apartment or floor No. 10 there is a fire, and if the door to the apartment is opened, then the smoke will enter into the hallway area. When the door between the stairwell and the hallway is opened, the pressure from the hallway will increase which will push the smoke backwards into the apartment.

Although the detailed description describes and illustrates various preferred embodiments, the invention is not so limited. Many modifications and variations will now occur to a person skilled in the art. For a definition of the reference may be had to the appending claims.