DE9409176U1 - Smoke protection device for a closed stairwell - Google Patents

Description

DE 6722 · :* * ^{: :} ""Pafertfehwalt

* Diploma in physics

Reinfried Frhr« v, Schorlemer

34117 Kassel Brüder-Grimm-Platz 4-Telephone (O561) 153 35

Pafamax Brandschutztechnik GmbH, 34123 Kassel
Smoke protection device for a closed stairwell

The invention relates to a smoke protection device of the type specified in the preamble of claim 1.

Each necessary staircase must be located in a separate, spatially connected stairwell arranged against an external wall.

Internal stairwells are permitted if their use cannot be endangered by smoke ingress and if there are no other concerns regarding fire safety.

In buildings of building classes E (the floor of none of the floors is more than 7 m above the ground surface), F (buildings in which the floor of none of the floors is more than 14 m above the ground surface) and G (buildings in which the floor of none of the floors is more than 22 m above the ground surface), no more than four apartments or other units of comparable size may be directly connected to a stairwell per floor.

If there are a larger number of usage units, these must be connected to the stairwell by publicly accessible corridors.
20

Internal stairwells in buildings with more than five floors above ground level must have lighting that is independent of the general lighting (emergency lighting).

For interior staircases, a

Smoke extraction device with a size of at least 5% of the floor area, but at least 1 square meter, must be installed. Exceptions can be permitted if the smoke is extracted in another way (§ 34 Stairwells, Hessian Building Code of December 20, 1993, representative of the building code of all federal states).

For interior staircases, further requirements and descriptions can be found in the decree concerning admissibility and building control requirements for interior staircases in residential buildings below the high-rise limit: 10

1. Only four apartments per floor may be accessed from an internal stairwell.

2. The interior staircase may only be accessed from the floor via an anteroom or a publicly accessible corridor no longer than 10 m long

or corridor section be accessible.

3. The door between the stairwell and the vestibule as well as between the vestibule and the publicly accessible corridor must be at least fire-retardant and self-closing. The apartment entrance doors

must be tightly sealed. Doors with a flush-fitting or rebated solid-walled door leaf and a seal on at least three sides are considered tightly sealed. Glazing in these doors is not permitted.

4. A smoke extraction device is installed at the highest point of the stairwell.

with an aerodynamically free cross-section of at least 5% of the floor area of the stairwell, but at least 1 square meter. The smoke extraction device must have an equally large supply air opening on the ground floor, coupled to the smoke extraction device

The air supply opening can be the front door if it is the appropriate size and has a locking device.

»

5. There must be a backup power supply for the lighting of the interior

Escape routes must be available.

The following applies to interior stairwells in residential buildings with more than five floors up to the high-rise limit:

1. Only four apartments per floor may be separated from an interior

Staircase can be accessed.

2. The interior staircase may only be accessed from the floor via a

The vestibule should have a floor area of at least 3 square meters and a minimum width of 1 meter.

3. Doors between the interior staircase and the vestibule and between the vestibule and the floor must be at least

be fire retardant and self-closing.

4. The interior stairwell must be equipped with an automatically controlled smoke extraction device.

5. The interior staircase and the associated anteroom must be ventilated with a ventilation system with fans so that a vertical air volume flow of at least 5000 nrVh is available for five floors, flowing from bottom to top. For each additional floor up to the high-rise limit, an additional 1000

m ³ /h required.

6. The ventilation system must be automatically activated by an acoustic and optical fire alarm system with smoke detectors, which must be installed in the room in front of the anteroom.

become.

7. The ventilation system can also be designed for an air volume flow of at least

·· ■ 1

• * I

· * 1

· I

at least 5000 mVh in up to three anterooms directly above one another belonging to a stairwell, if the two openings required for ventilation in each anteroom are provided with tightly closing flaps which, in the event of smoke development, by triggering the smoke detectors and simultaneous activation of the

When the ventilation system is activated, it can only be opened automatically on the respective floor.

8. The maximum overpressure created in the interior stairwell and in the vestibules by the air volume flow must not exceed 50 Pa.

exceed.

9. Outside air openings for ventilation systems must be arranged so that they are protected against the ingress of smoke.

10. There must be a backup power supply system which switches on automatically within 15 seconds in the event of a failure of the general power supply and provides power for the safety devices in the interior stairwell and vestibules

— takes over. The backup power supply system must be able to operate for at least

one hour operation of all safety devices.

The following applies to high-rise buildings (Guidelines on the construction and facilities of high-rise buildings):

.25 — 1. High-rise buildings are buildings in which the floor of at least one

The living area is more than 22 metres above the specified ground surface.

2. In high-rise buildings, at least two stairwells or, instead of two stairwells, one safety stairwell are required.

3. If a safety stairwell is the only stairwell within the building or a fire compartment, it must be installed on the outside wall

-5-lie or be separated from it.

4. If two or more necessary stairwells are present, they must be located opposite each other and in different smoke zones.

5. In high-rise buildings with a height of more than 60 metres, at least two safety stairwells must be provided.

6. Doors to publicly accessible corridors and anterooms must be smoke-tight and at least fire-retardant T 30.

7. Smoke extraction devices with an aerodynamically free cross-section of at least 5% of the respective stairwell floor area, but at least 1 square meter, must be installed at the highest point of the stairwell.

8. Internal stairwells may be permitted if their use cannot be endangered by the ingress of smoke and if there are no other concerns regarding fire safety.

These requirements are met if the following is observed:

a) The interior stairwells may only be accessible via vestibules.

25·- - ■■ —

b) The stairwell and the vestibules must be fitted with a ventilation system which permanently achieves at least one air change per hour. In the event of a fire, this or another ventilation system must flush the stairwell and the vestibules from bottom to top with an air flow rate of at least 10,000 m ³ /h.

c) The maximum overpressure in the stairwell and in the vestibules caused by this air volume flow must not exceed 50 Pa.

-6-

d) The increased ventilation must be activated automatically by smoke switches on each floor.

e) The ventilation system for fire must be connected to the emergency power supply. It must be connected to the outside, including the intake pipe, in such a way that

to arrange and ensure that fire and smoke cannot be transmitted through them into the stairwell.

Safety stairwells and their entrances must be designed in such a way that fire and smoke cannot penetrate into them.

If an internal safety stairwell is permitted, it may only be accessible via a security lock on each floor.

The security lock must have smoke-tight and at least fire-retardant doors.

Each stairwell with the associated security locks must have its own ventilation system.

The stairwell, its entrances and the ventilation system must be designed in such a way that fire and smoke cannot penetrate into it.

These requirements are met if the ventilation system of the stairwell is set up with a vertical air volume flow of at least 10,000 m ³ /h or is supplemented by a second ventilation system for all airlocks so that in the event of a fire, with the airlock doors open on the floor affected by the fire and with the most unfavourable pressure in the stairwell in front of the airlock, an air volume flow of V = kxbxhin m ³ /s flows into the fire room. Where b and h are the width and height of the door in metres, and k takes into account the temperature that can occur in the room adjacent to the stairwell in the event of a fire.

If the lock is connected to a publicly accessible corridor, k is to be set at 1.5, in all other cases at 1.8.

The pressure difference required for this volume flow depends on the way in which the smoke gases are discharged from the fire room to the outside.

If the smoke gases are pressed out of the fire room, for example, from horizontal ducts, the pressure in the lock must be increased in accordance with the flow resistance. -

If shafts or exhaust fans are installed that create a negative pressure in the fire room, the pressure in the lock can be reduced by the amount of the negative pressure created in the fire room in windowless rooms. 10

In rooms with windows, the ventilation system must be designed for a pressure in the airlock of at least 10 Pa.

No door may be subjected to a pressure higher than 50 Pa. 15

This must be ensured by automatic devices (pressure relief flaps to the outside or to the anteroom or corridors with exhaust air openings to the outside, regulation of the supply air flow).

Compliance with the regulations described does not cause any significant difficulties if the buildings in question are new buildings. In the case of old buildings, however, compliance with the regulations is often impossible. This applies in particular if the individual floors or apartments or similar provided on them are directly adjacent to the stairwell, especially an internal stairwell, so that there are no vestibules or corridors and therefore no security locks can be provided. Apart from that, the regulations only require that smoke development in the stairwell is largely avoided if defined conditions exist and if ventilation systems or similar are calculated and designed accordingly. Whether the prevention of smoke in the stairwell in the event of a fire also works if completely different conditions happen to exist when the fire starts, e.g. doors, windows, locks or similar that are assumed to be closed are actually closed, is neither aimed at nor guaranteed by the regulations, especially since they do not contain any provisions on this, as in the

In the event of a fire, the prescribed air flows and/or overpressures can actually be maintained and/or monitored. The regulations alone therefore do not provide a useful means of safely preventing smoke in stairwells.

The invention is based on the task of remedying this situation and designing the smoke protection device of the type described above in such a way that the penetration of smoke into the stairwell can be permanently and controlled prevented, even if external conditions change unfavorably. In addition, the smoke protection device should be largely independent of the type of closed stairwell and the adjacent floors and therefore be able to be used for all types of closed stairwells.

The characterizing features of claim 1 serve to solve this problem. Further advantageous features emerge from the subclaims.

The invention has the significant advantage that in the event of a fire a preselected overpressure in the stairwell is ensured by regulation. As a result, the smoke protection device operates largely independently of any circumstances that may occur in the event of a fire. It is also irrelevant whether the smoke protection device is used in conjunction with an internal stairwell or a stairwell adjacent to an external wall and/or whether apartment doors or the like lead directly into the stairwell or are separated from it by vestibules, corridors, locks or the like.

The invention is explained in more detail below using an embodiment which is shown schematically in the attached drawing.

The drawing shows a building 1 which has a number of above-ground floors 2, 3 and 4, which are only schematically indicated by floors or ceilings 5. The building 1 also has an internal staircase 6 with schematically indicated steps 7 and a roof 8 with a roof truss 9. An exhaust air opening 10 leading to the outside is formed in the roof 8, which can be optionally opened or closed by means of a schematically indicated flap 11.

-9-

The flap 11 is provided with a lever mechanism 12 which is connected to an actuator 14, e.g. a servomotor, a hydraulic system or the like.

A smoke detector 15 is installed on each floor 2, 3 and 4 and preferably also in the roof structure 9. This is connected via a line 16 to a circuit arrangement 17, which is arranged, for example, in a basement room 18 of building 1 and housed in a switch cabinet. Optical smoke detectors, such as those sold under the designation ORM 130/A EX by Hekatron GmbH, D-79295 Sulzburg/Baden, are preferably suitable as smoke detectors 15. The circuit arrangement 17 is also connected to the actuator 14 via a line 19.

In an upper and lower area of the stairwell 6, a manually operable switch 20 is also installed, which is connected to the circuit arrangement 17 via a line 21 and can consist of a conventional fire button. Finally, pressure sensors 22 are installed at various points in the stairwell 6, in particular near the exhaust air opening 10," which are connected to the circuit arrangement 17 via a line 23.

Adjacent to the staircase 6 are doors 25 which are provided with schematically indicated door closers 26. The door closers 26 normally keep the doors 25 closed or close them automatically. Normally, the door closers 26 are set to a relatively low closing pressure. However, they can also be set to a higher closing pressure by remote control, for which purpose they are connected via a line 27 to the circuit arrangement 17, from which this switching is possible by remote control. It is understood that the doors 25 are usually in the

Apartments can be opened. Door closers suitable for the purposes of the invention are sold, for example, by the companies Geze GmbH & Co., D-71229 Leonberg, and DORMA GmbH 4- Co. KG, D-58256 Ennepetal, under the names GEZE TS 4000 EFS and DORMA TS 73 EMR.
30

In a lower area of the stairwell 6, e.g. a basement room 29, a ventilation system 30 is installed, which is also connected to the circuit arrangement 17 via a line 31 and, for example, at least one sufficiently powerful

· 9 ·

- 10-

powerful fan that can convey outside air into the stairwell and is dimensioned, depending on the size of the stairwell 6, so that it can generate a preselected overpressure in the event of a fire, even if one or more of the doors 25 are fully or partially open. 5

Finally, in a preferably lower area of the stairwell 6, a supply air opening (not shown) is provided, which can consist, for example, of a front door, but also of an additional opening designed corresponding to the exhaust air opening 10 and closable with a controllable flap.

The circuit arrangement 17 forms, among other things, a control device. In this control device, the air pressure in the stairwell 6 forms the controlled variable, which in the event of a fire is to be brought or maintained at a preselected setpoint provided by a setpoint device, whereby the setpoint device can also be designed to continuously change or adjust the setpoint. The pressure sensors 22 are used to measure the controlled variable, and their actual values are compared with the value provided by the setpoint device. The control deviation resulting from the comparison is fed to a controller, which generates a control signal that is fed to the actuator 14 of the control device in order to open or close the exhaust air opening 10 more depending on the measured excess pressure.

The pressure sensors 22 are preferably designed as differential pressure gauges which measure the differential pressure between the pressure prevailing in the stairwell 6 and the pressure prevailing outside the building 1.

To provide an audible indication of a fire, the circuit arrangement 17 can be connected via a line 33 to a corresponding alarm system 34 (bell, horn, siren or the like).

The circuit arrangement 17 and the parts connected to it are operated by the usual power grid. If this fails due to fire or another fault, the required electrical energy is supplied by an emergency power supply 35, which is connected to the circuit arrangement 17 via lines 36. This emergency power supply 35 is preferably designed and set up in such a way that, unlike previously required, after the failure of the usual power grid, when operated by battery, it is already ready for use within

of milliseconds, i.e. practically without delay, the further operation of the circuit arrangement 17 takes over, without causing malfunctions, for example due to failure of relays, contactors or the like.

The smoke protection device described works as follows:

If a fire breaks out on one of the floors 2, 3 or 4 or in an apartment located therein, at least one of the smoke detectors 15 is triggered when smoke penetrates into the stairwell 6, whereby a corresponding electrical fault signal is sent to the circuit arrangement 17 via line 16. Alternatively, this fault signal can also be triggered by a person who discovers the fire manually operating one of the switches 20. As a result of the fire or smoke alarm, the circuit arrangement 17 generates an electrical signal in line 33 that triggers the alarm device 34 and an electrical signal in line 31 that switches on the ventilation system 30 or the fans installed in it. At the same time, the circuit arrangement 17 emits a switching signal via line 23 to switch all door closers 26 to the high closing pressures. Finally, the control device is also activated, whereby the actual signals from the pressure sensors 22 of the air pressure prevailing in the stairwell 6 are compared with a target pressure specified for the event of a fire (e.g. between 10 and 50 Pa).

The activation of the ventilation system 30 results in the air flow generated by it flowing from bottom to top through the stairwell 6. The ventilation system 30 is dimensioned in such a way that the air flow generated is sufficient to generate the preselected overpressure in the stairwell 6, at least when the exhaust air opening 10 is closed. However, this should preferably also apply in the case that one or more doors 23 are fully or partially open or are opened in order to be able to maintain the overpressure for the entire duration of the fire or at least for as long as possible. The ventilation system 30 is therefore appropriately dimensioned overall for a volume flow that is significantly greater than is required to generate the desired overpressure with the exhaust air opening 10 and doors 23 closed, i.e. under ideal conditions.

•**♦

- 12-

After the ventilation system 30 has been activated, the circuit arrangement 17 continuously monitors a selected pressure sensor 22 via line 23, for example the pressure sensor 22 located in the immediate vicinity of the exhaust air opening 10. If this indicates that the preselected air pressure has been reached, the controller of the circuit arrangement 17 sends a control signal to the control element 14 via line 19 such that the flap 11 is subsequently opened or closed in such a way that the air pressure indicated by the monitored pressure sensor 22 fluctuates within a certain tolerance range around the desired setpoint, as is characteristic of control devices. This not only monitors the maintenance of the desired overpressure in the stairwell 6, regardless of the conditions existing in the individual case, but also ensures that this overpressure is actually achieved and therefore no smoke can enter the stairwell 6.

Alternatively, it would be possible to use the supply air opening or a flap associated with it as an actuator for the control process or to change the air flow emitted by the ventilation system 30, for example by rotating the fans slower or faster or by switching them on and off alternately.

The use of several smoke detectors 15, pressure sensors 22 or similar serves, on the one hand, the purpose of creating a redundant system that is still functional even if one of the components fails. On the other hand, these parts can be assigned to the individual floors 2, 3 and 4 or apartments as required in order to achieve greater response sensitivity or to enable the smoke protection system to be put into operation more quickly. It goes without saying that the lines 16, 19, 23, etc. can also be present multiple times for redundancy reasons.

After switching over, the door closers 26 are preferably set to a closing pressure that is adapted to the overpressure selected in the stairwell 6 in such a way that the doors opening to the apartments can still be operated relatively easily despite the overpressure (latch and bolt function) and the overpressure generated by the overpressure in the stairwell 6 does not result in excessive pressure being exerted by the latches, bolts or the like on the associated frame parts. This prevents the doors from becoming insurmountable obstacles in the event of a fire, e.g. for children and the weak or the like.

•-13-

In addition, the increased closing pressure ensures that the doors continue to close automatically despite the overpressure in the stairwell 6 and do not jump open when you try to open them. The increased closing pressure is to be selected depending on the overpressure created in the stairwell 6. 5

Furthermore, provision can be made to install additional manually operable switches 37 at preselected locations in the stairwell 6, by means of which the ventilation system 30 can be switched on and/or the flap 11 or the like can be operated even if no fire or smoke is reported, for example in order to temporarily ventilate the stairwell 6. The switches 37 are expediently connected to the circuit arrangement 17 via a line 38. A further switch can be provided in order to be able to return the circuit arrangement to its initial state after a fire, a test run or the like.

The invention is not limited to the described embodiment, which can be adapted in many ways. This applies on the one hand to the design and arrangement of the described components. On the other hand, the schematically indicated doors 23 can also lead to special anterooms, corridors or locks, which are separated from the actual apartments by further doors and may be provided with further ventilation systems. In this case too, the described regulation ensures that no smoke can get into the stairwell 6, provided that the overpressure generated there is greater than the overpressure prevailing in the anterooms or the like. In addition, it can be a stairwell that borders on an external wall.

In a preferred embodiment, the circuit arrangement 17 is designed so that the exhaust air opening 10 initially remains open for a while when smoke occurs or is opened. This serves the purpose of allowing existing smoke to escape into the open air as quickly as possible. Only then is the control device activated in order to achieve the described effect.

Claims (7)

Expectations 1. Smoke protection device for a closed stairwell (6) with a ventilation system (30) to be arranged therein and intended to produce an overpressure and having at least one fan, at least one smoke detector (15), a circuit arrangement (17) connected to the ventilation system (30) and the smoke detector (15) for switching on the ventilation system (30) when smoke occurs, at least one supply air opening located in a lower area of the stairwell (6) and at least one exhaust air opening (10) located in an upper area of the stairwell (6), characterized in that the circuit arrangement (17) has at least one pressure sensor (22) to be mounted in the stairwell (6) and with this and the ventilation system (30) and/or the supply air opening and/or the exhaust air opening (10) a control device for producing and maintaining a preselected overpressure in the stairwell (6) after the smoke detector has been triggered (15) forms. 2. Smoke protection device according to claim 1, characterized in that the exhaust air opening (10) has a closable flap (11) and the control device has an actuator (14) for opening or closing the flap (11). 3. Smoke protection device according to claim 1 or 2, characterized in that the control device has an adjustable setpoint value transmitter for setting the preselected overpressure. 4. Smoke protection device according to one of claims 1 to 3, characterized in that doors (25) bordering the stairwell (6) have automatic door closers (26), the closing pressures of which can be switched by remote control at least from normal, low values to high values, and that the circuit arrangement (17) is connected to the door closers (26) in such a way that they are switched to the high values when smoke occurs. 5. Smoke protection device according to one of claims 1 to 4, characterized in that the circuit arrangement (17) is designed so that the exhaust air opening (10)
If smoke occurs, the door is initially opened or remains open for a preselected period of time and only then is the control device activated. 6. Smoke protection device according to one of claims 1 to 5, characterized in that the circuit arrangement (17) is connected to an emergency power supply (35) in such a way that no malfunction occurs in the event of failure of the usual power network. 7. Smoke protection device according to one of claims 1 to 6, characterized in that the circuit arrangement (17) is connected to at least one switch (20) for manual
To switch on the ventilation system (30) and to switch the door closers (26)
connected.