TECHNICAL FIELD

The present invention relates to an arrangement for pressurizing a space in e.g. a building, and/or evacuating smoke from the space in case of a fire.

BACKGROUND

There are existing systems used for pressurizing a space in a stairwell in case of a fire. Some examples are shown in a document issued in April 2012 by the Swedish company Hagab Industri AB and entitled "Resque Brandgaskontrollsystem". The arrangement called "Resque 2" in this document involves a system for pressurizing a stairwell with a constant air flow from a fan and a damper included in the system for controlling the overpressure generated in the stairwell.

This known system further comprises electrical means to control its operation, which involves a lot of work with cable pulling, e.g. between the system part in the roof area and the system part in the basement area which makes this system expensive and complex. Due to this complexity, many subcontractors need to be scheduled so that different parts of the system can be installed at the right time which in turn may lead to long lead times and increased costs. The system further includes parts which are sensitive to the surrounding environment, such as parts which may stop functioning if the temperature rises above a certain level and parts which over time may be adjusted or re-calibrated. This is of course a severe drawback in a system configured to be in operation during fire conditions.

A similar concept is known from JP-2007024469A where a smoke removal system is disclosed, which requires several fans and which basically suffers from the same drawbacks as the "Resque 2" system above.

Another known arrangement is disclosed in WO-03038283A which relates to a method and a device for keeping escape and rescue paths free of smoke. The arrangement includes a ventilator and a system of flaps which are self-closing by means of a tension- compression-spring system. A problem with this known concept is that the spring system is sensitive to high temperatures which may cause it to break or not operate as it should, which in turn makes this device non-reliable in case of a fire.

Another problem with this known arrangement is that the flaps are affected by the fan unit in this compact arrangement, which has negative impact on the operating ability of the device.

Yet another known example of prior art is disclosed in WO-2009101239A which relates to a system for pressurizing the inside space of a building in a fire scenario, wherein the system comprises a fan and one or more louvers. It is also configured to remove smoke from the space. First, this system is only suitable for the roof of a building which makes it dependent on the design of the roof, not flexible and only usable in a building. The louvers are arranged as external components on top of the system which means that they are in communication with the outdoor air and opened by means of a motor in case of fire to let air flow into the system.

A disadvantage of this known system is that it is dependent on the use of a motor and its needs of driving means. These means are usually electrical which may be affected in a negative way by high temperatures occurring during a fire. Also, a motor driven system is expensive and demands maintenance work. Further, the louvers only provide a solution for letting air into the system during pressurization and out during evacuation, and it can not control the pressure generated in the space.

Hence, the prior-art system described above is dependent on the appearance of the space in the building and it is not able to provide an overpressure that is constant around stated regulations on fire safety. In practice, systems of this kind include a pressure meter which may have to be adjusted or re-calibrated over time. In risk scenarios, the pressure meter is exposed to high temperatures which may lead to malfunction of the entire system.

Further examples of background art are disclosed in DE202004016229U, EP-2500663A, US-20110179732A and US-5788571A.

From the above, it is evident that there is room for improvements of arrangements of this kind in connection with escape spaces, in particular in buildings. SUMMARY

An object of the present invention is to provide a novel arrangement for pressurizing a space and/or evacuating smoke from this space in case of a fire, which is improved over prior art. This object is achieved by the technique defined in the appended independent claims; certain embodiments being set forth in the related dependent claims.

In one aspect of the invention there is provided an arrangement for pressurizing an escape space and/or evacuating smoke from this space in case of a fire, wherein the arrangement comprises: an air flow directing device defining a first flow path between an air inlet and an air outlet; a fan unit arranged in the first flow path and configured to pressurize and/or evacuate smoke from the space by generating air flow in the first flow path and out of the air outlet which is in communication with the space; and

a damper unit arranged in a second flow path forming a circuit within the air flow directing device, said damper unit being configured to open and close during said pressurization and/or evacuation and thereby control the airflow out of the air outlet.

This arrangement creates a safe rescue route, in case of a fire, for people present in the area of the fire needing to get out, since it provides the space with a constant overpressure which is controlled by the damper unit so that no smoke enters the space of the escape route. The overpressure also provides a smoke free passageway for the firemen as they enter the space for rescuing people still in the area or for extinguishing the fire. It is also a compact arrangement which is easy to install and control since the air flow is provided within the arrangement.

The air flow directing device may comprise a duct system defining the first flow path and the second flow path, and forming the circuit. A duct system of this kind can be built by duct components of low complexity which makes the system easy to produce and install.

In an embodiment, the duct system comprises a first duct element arranged with the air inlet which is in communication with air outside the space and with the air outlet which is in communication with air in the space, and configured to accommodate the fan unit, and a second duct element arranged with a first end in communication with the first duct element between its inlet and the fan unit and a second end in

communication with the first duct element between the fan unit and its outlet, configured to accommodate the damper unit. This design is advantageous in that the circuit formed by the two duct elements protects the flow from interruptions since it is entirely located within the air flow directing device.

In an alternative, the flow directing device comprises a casing defining the first flow path and the second flow path, and forming the circuit. Since all main components of the arrangement can be contained in the casing, the arrangement as a whole can be made very compact. This is an advantage when the arrangement is to be installed in buildings where the space for installation is limited. The casing may comprise two chambers at least partially defined by the fan unit and the damper unit within the casing.

Preferably, the air inlet and air outlet are formed in the walls of the casing at spaced locations thereby defining the first flow path; the fan unit and damper unit being arranged within the casing Hence, the location of the inlet and outlet is flexible and in principal optional which opens up for standardization of casings depending on where the arrangement is to be installed. This may reduce costs, both in manufacturing and during installation. A design of this kind is also very compact.

Further, in yet another embodiment the fan unit is reversible in order to generate air flow in an opposite direction through the first air flow path. This allows the arrangement to both pressurize the space and evacuate smoke from it which is a desired feature for quickly extinguishing the fire.

In one embodiment, the damper unit is configured to open if the pressure within the space is above a desired value and to close partially or fully if the pressure is below the desired value, preferably by means of mechanical counter weight means. This is advantageous since the pressure level then may be kept at a relatively constant value during the entire rescue scenario and at the same time prevent smoke from entering the escape route and still allowing people to safely and with a preferred amount of force open a channel, e.g. a door, facing the escape route.

The mechanical counter weight means may comprise at least one weight assembly. It is very advantageous to use a weight assembly since its mass is easy to adjust depending on the demands of every location and situation. It is also a cheap way of providing a counter weight to the overpressure.

In yet another embodiment the weight assembly comprises at least one removable weight element which is advantageous since the mass of the weight assembly then easily may be adjusted.

In another embodiment, the arrangement is connected to a sensor and/or a manually operated device, e.g. a smoke detector or a push button, arranged in a space outside the escape space, and configured to send a signal to the arrangement to start pressurizing said space as it detects smoke. This provides a safe system for starting the arrangement without the help of a person pressing a button or the like.

In another aspect of the invention there is provided a damper unit for opening and closing at certain pressure levels of a pressure within a space. The damper unit comprises a housing through which air is configured to flow in one direction, at least one pivotable damper blade configured to open and close the air flow, and mechanical counter weight means connected to the damper blade for allowing the blade to open and close at said pressure levels.

The damper unit can be installed in a system for pressurizing an escape space and/or evacuating smoke from such space in case of a fire. The counter weight means is configured to operate as a counter weight against an overpressure generated in the system and to control the overpressure so that an accepted pressure level is maintained. Preferably, the counterweight means is adjustable so that it can be set or calibrated with a desired opening/closing operation depending on pressure levels in the system. The operation of the damper unit may be automatically controlled and balanced by the air pressure acting on it, which is advantageous in systems of the present type.

In an embodiment, the damper unit comprises a number of damper blades each of which being connected to a weight assembly of the counter weight means. The weight assembly may comprise at least one removable weight element by means of which suitable setting and balancing of the damper unit can be achieved. The damper blades may be interconnected and thereby operated at the same time by the weight assembly, which provides an efficient operation of the damper unit. In yet other aspects of the invention there are provided methods for installing and/or calibrating an arrangement for pressurizing an escape space and/or evacuating smoke from said space in case of a fire; pressurizing the space and evacuating smoke from said space.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be described in the following; references being made to the appended diagrammic drawings which illustrate non-limiting examples of how the inventive concept can be reduced into practice.

Fig. 1 is a schematic cross section illustrating two possible locations of an arrangement installed in a building and involving embodiments of the invention,

Fig. 2 is a schematic view of an arrangement according to an embodiment, Fig. 3 is a schematic view of an arrangement according to an alternative embodiment,

Fig. 4 is a schematic view of an arrangement according to yet an alternative embodiment,

Fig. 5 is a schematic view of an arrangement according to an alternative embodiment,

Fig. 6 is a schematic view of an arrangement according to yet another alternative embodiment,

Fig. 7 is a perspective view of a non-return damper unit according to an embodiment of the invention,

Fig. 8 is a side view of the damper unit in Fig. 7, and

Fig. 9 is a front view of the damper unit in Fig. 7.

DETAILED DESCRIPTION OF EMBODIMENTS

With reference to Fig. 1, two systems or arrangements 100, 200 according to a first and a second embodiment are provided within a multi-storey building B having several rooms R or apartments each with a door Dl facing a rescue route or escape space, e.g. a stairwell S, inside or close to the rescue area through which people may escape in case of a fire, in this case the stairwell S. In this example, the first arrangement 100 is installed in the basement area of the building B and is further described in Fig. 2, whereas the second arrangement 200 is installed in the roof area of the building B and is further described in Fig. 3. In the building B shown in Fig.l, one arrangement may be installed to provide a safe escape route for people in the building B by pressurizing the stairwell S, either by the first arrangement 100 or the second arrangement 200, so that people in the building B might get out safely through an outer door D2 on ground level G.

The arrangements 100, 200 are in communication with air outside the building B and with air within the stairwell S so that the arrangements 100, 200 are able to pressurize the stairwell by urging air from outside the building into the stairwell S. Due to the location of the second arrangement 200, it is also able to evacuate smoke from the stairwell S to the outside of the building B if the fan of the arrangement is reversed (to be further described below).

Further, the arrangements 100, 200 are connected to one or more sensor units SU and/or a manually operated device, for instance smoke detectors or a hand-operated push button. Sensors are preferably provided in each room R or apartment of the building B. The sensor unit SU detecting a fire in a room R sends a signal to the arrangements 100, 200 to start pressurizing the escape route, i.e. the stairwell S, so that people in the building B will be able to safely get out before the firemen arrive at the scene. Sensor units SU may in another embodiment be provided in the stairwell S or at other suitable locations.

The arrangements 100, 200 are also connected to a control unit CU which in this case is located on the ground floor of the building B (ground level G). The control unit CU provides easy access to the arrangement 100, 200 for firemen arriving at the scene, who then first may safely rescue people still trapped in the building B and then stop the pressurization and reverse the arrangement 200 so that it starts to evacuate smoke from the building B which makes the fire extinction easier and faster.

With reference to Fig. 2 the arrangement 100 according to the first embodiment comprises an air flow directing device, here in the shape of a duct system 120.

Furthermore, it includes a fan unit 130 and a damper unit 140. The fan unit 130 is preferably an axial fan with rotatable fan blades 131 and the damper unit 140 is preferably a non-return damper. This arrangement 100 is preferably installed in the basement area of the building B, but it may in other applications be arranged wherever suitable.

The duct system has an inlet 121 and an outlet 122. The inlet 121 is in communication with air outside the building B and the outlet 122 is in communication with air within the stairwell S. Further, the duct system 120 includes a first duct element 123 which is substantially straight and a second duct element 124 which forms a parallel bypass duct circuit. The first duct element 123 extends from the inlet 121 to the outlet 122 and is configured to accommodate the fan unit 130 somewhere between the inlet 121 and the outlet 122. Since the first duct element 123 is substantially straight it allows smooth flow of air from the inlet 121 to the outlet 122 without any disturbance. The second duct element 124 may have a C shape (or consist of two 90° bends), and it is connected to the first duct element 123 at two spaced locations. The first end 125 of the second duct element 124 is connected to the first duct element 123 somewhere between the inlet 121 and the fan unit 130, whereas the second end 126 of the second duct element 124 is connected to the first duct element 123 somewhere between the fan unit 130 and the outlet 122. The second duct element 124 is configured to accommodate the damper unit 140 somewhere along its extension so that the fan unit 130 and the damper unit 140 are arranged in parallel.

The assembly of the first and second duct elements 123-124, the fan unit 130 and the damper unit 140 forms a passageway and a loop, respectively, for the air to flow through. In other words, the duct system 120 defines a first air flow path A-B in which the fan unit 130 is arranged, and a second air flow path A-C in which the damper unit 140 is arranged. In case of a fire, a signal is sent form the sensor unit SU (Fig. 1) to the arrangement 100 which starts the fan unit 130. Then the fan unit 130 starts to rotate its fan blades 131 in a direction which sucks air from the outside into the inlet 121, in the direction of the arrow A, and through the first duct system 123, the fan unit 130 and out through the outlet 122, in the direction of the arrow B, into the stairwell S. This main flow path is illustrated by the dotted line A-B.

The flow of external air into the space of the stairwell S generates an overpressure in the stairwell S so that smoke from an adjacent room R is not able to spread into the stairwell S. Meanwhile, the overpressure generates a compressive force on the doors Dl leading to the stairwell S which means that a person trying to get out must push the door Dl harder to open it. Therefore, the compressive force has to be set so that it does not exceed a maximum allowed force making the door too heavy to open. The maximum force of the compressive force is stipulated in official regulations for these types of arrangements, and in this case a preferred maximum force value may be about 150 N. Hence, the overpressure in the stairwell S must be controlled at a maximum pressure value so that the generated compressive force is not too high but also make sure that the overpressure is enough not to allow smoke to spread into the stairwell S. This control is achieved by the damper unit 140 further described below.

The damper unit 140 includes a housing 141, at least one damper blade 142, in Fig. 2 five blades 142, and mechanical counter weight means, here in the shape of a weight assembly 143. As can be seen, the damper unit 140 allows air to flow in one direction, from the second end 126 of the second duct element 124 to the first end 125 of the second duct element 124 forming the loop for air to flow through if the overpressure in the stairwell S exceeds the maximum pressure value.

The mechanical counter weight assembly 143 comprises a number of detachable weight elements 143 a and it is connected to the damper blades 142 by means of supporting means 144 allowing the weight assembly 143 to hang freely with just the gravity affecting it. The counter weight assembly 143 is configured to keep the damper blades 142 substantially closed during air pressures below the maximum pressure value.

The damper blades 142 are kept substantially closed to allow the capacity of the fan unit 130 to slightly drop which may happen during operation, but still maintain an even pressure level. As soon as the overpressure exceeds the maximum pressure value, the damper blades 142 start to open allowing air to flow also in the direction of the arrow C, along the dotted line, through the damper unit 140 and towards the inlet 121 or fan unit 130, thereby lowering the overpressure and keeping it around the maximum pressure value. If a door Dl is opened into the stairwell S the overpressure drops, which leads to less pressure on the damper blades 142 which then close by means of the counter weight assembly 143. Hereby, the damper unit 140 can be regarded as a self-regulating device. The total weight of the assembly 143 may be varied by altering the number of weight elements 143 a of the weight assembly 143, depending on the overpressure and the maximum allowed overpressure and compression force, and it is configured to be calibrated once installing the arrangement or when major modifications are made to the building B which may have impact on the pressurization of the escape space S.

The arrangement 100 shown in Fig. 2 is connected to at least one sensor unit SU, e.g. a fire alarm, and a control unit CU to which the firemen have access in order to control the arrangement.

As shown in Fig. 3 the arrangement 200, which is similar to the arrangement shown in Fig. 2, is provided with a duct system 220 including an inlet 221 and an outlet 222, a first duct element 223 and a second duct element 224 with a first end 225 and a second end 226. Further, the arrangement 200 comprises a fan unit 230 with rotatable fan blades 231, and a non-return damper unit 240 with a housing 241, at least one blade 242, a mechanical counter weight assembly 243, and supporting means 244. The main components of this second arrangement 200 are basically the same as in the first arrangement 100.

This arrangement 200 is installed in the roof R of the building B and is of the same type as the one shown in Fig. 2 but rotated about 90°. The first duct element 223 is now extending substantially vertically from its inlet 221 to its outlet 222 and the weight assembly 243 is arranged within the damper unit 240 and connected to the damper blades 242 in such way that it hangs freely only the gravity affecting it. Since the arrangement 200 is installed in the roof area it is provided with a reversible fan unit 230 which means that the arrangement 200 is also able to evacuate smoke from the building.

Preferably, the reversible fan unit 230 is designed to withstand such high temperatures which may occur in fire scenarios. Since smoke and warm air rise, it is advantageous to arrange this kind of arrangement in the roof area R and to provide a reversible air flow to help the firemen extinguish the fire. The arrangement 200 is connected to the control unit CU by which the firemen may turn off the arrangement and/or turn on the evacuation of the smoke by changing the rotational direction of the fan blades 231 of the fan unit 230. The damper unit 240 is closed in the evacuating state of the arrangement 200. In Fig. 4 there is shown an arrangement 300 according to yet another embodiment which comprises an air flow directing device, here in the shape of a two- chamber casing 310. Furthermore, it includes a fan unit 330 with rotatable fan blades 331 and a non-return damper unit 340. The damper unit 340 includes a housing 341, damper blades 342, a counter weight assembly 343 and supporting means 344 of the same type as shown in Fig. 3. In the arrangement 300, air may flow freely within the casing 310 when the fan unit 330 is switched off. As soon as the fan unit 330 is switched on, air from outside flows from the inlet 321 of the casing 310, in the direction of the arrow A and along the dotted line leading through the fan unit 330 towards the outlet 322 of the casing 310 and into the space S being pressurized, in the direction of the arrow B.

If the overpressure is above the allowed maximum pressure value, air may flow in the direction of the arrow C, through the damper unit 340 towards the inlet 321 or the fan unit 330, thereby generating a circuit of air. Hence, the casing 310 defines a first flow path A-B in which the fan unit 330 is arranged, and a second flow path A-C in which the damper unit 340 is arranged. Preferably, the fan unit 330 and the damper unit 340 are arranged in such a way that they form a partition defining a first chamber 301 and a second chamber 302 of the casing 310.

With reference to Fig. 5 an arrangement 400 similar to the arrangement 300 of Fig. 5 is shown. The differences between the two arrangements 300, 400 are the locations of the inlet 421 and the outlet 422 forming alternative paths for the air to flow when the arrangement 400 is in operation. Again, the two-chamber casing 410 defines a first flow path A-B including the fan unit 430 and a second flow path including the damper unit 440. The casing 410 has a partition formed by the fan unit 430 and the damper unit 440 which defines a first chamber 401 and a second chamber 402.

Fig. 6 shows an arrangement 500 similar to the arrangements 300, 400 above but where the non-return damper unit 540 is like the one shown in Fig. 2. Also, the positions of the inlet 521 and outlet 522 of the two-chamber casing 510 are different, which generates slightly different paths for the air flow. A partition is formed by the fan unit 530 associated with the damper unit 540 thereby defining a first chamber 501 and a second chamber 502. In all embodiments shown in Figs 2-6, the arrangement includes an air flow directing device in which there is an air flow circuit with a first path containing a fan unit and a second path containing a damper unit.

In order to protect the arrangement 200 from rain and dirt, and to prevent small animals from getting into the arrangement, an optional cover 600 (see Fig. 1) is provided. The cover 600 also protects people passing by the arrangement 200 on the roof R.

In Figs 7-9 a damper unit 140 of the type shown in Fig. 2 is illustrated in perspective, from the side and from the front. The housing 141 of the damper unit 140 has the shape of a square box with a circular opening 145. Inside the housing 141 there is a number of damper blades 142 pivotably connected to the housing 141 and configured to open and close the opening 145 by means of a mechanical counter weight assembly 143 having a number of weight elements 143 a arranged in a space within the housing 141 along one side if the same. The weight assembly 143 is connected to the damper blades 142 by means of supporting means 144 and may be accessed by opening a hatch 146. The supporting means 144 generally comprises two links 147, 148 wherein the first link 147 is attached to the weight assembly 143 and also rotatably connected to the second link 148. The second link 148 operates as a lever and is rotatably connected to a connection joint 149 associated with the blades 142. Since the weight assembly 143 is rotatably connected to the supporting means 144, it may hang freely within the space, with only the gravitation affecting it.

The three damper blades 142 shown in Figs 7-9 are interconnected and thereby operated all at the same time by the weight assembly 143.

The weight assembly 143 is configured to work as a counter weight against the overpressure generated by the arrangement and control the overpressure so that it maintains an accepted pressure level. When the overpressure is at an accepted level the weight assembly 143 keeps the damper blades 142 in their substantially or partially closed position, allowing only a low flow of air through the damper unit 140. When the overpressure exceeds the maximum pressure value, the damper blades 142 start to open so that more air may flow through the damper unit 140 which releases the pressure to an accepted level. As soon as the overpressure starts to exceed the accepted level, the damper blades 142 start to open. This means that the operation of the damper unit 140 is automatically controlled and balanced by the air pressure acting on it.

The damper unit 140 is of non-return type since air is allowed to flow into the housing 141 through the opening 145, but not in the opposite direction since the damper blades 142 then flip to their closed position and close the opening 145.

In other embodiments the mechanical counter weight means may be of a different kind than described above. It may sometimes be preferred to connect one weight assembly or weight element to each damper blade or ever attach a weight assembly or weight element to each blade.

To make sure that the weight assembly allows the damper blades to open and close at the right overpressure, the arrangement should be calibrated before use. In an embodiment, the calibrating procedure involves the following steps:

- starting the fan unit so that air from outside is drawn into the air flow directing device;

- leading the air flow through the air flow directing device and into the escape space thereby generating an overpressure in this space;

- measuring the compression force generated by the overpressure and applied to a surface of the escape space, preferably a door opening into this space; and

- setting the counterweight assembly so that the damper unit opens and closes at a certain compression force value, for instance 150 N.

Before calibration, all doors leading into the escape space have to be closed. The calibration procedure is performed by at least one person, preferably a number of persons positioned at different locations in the building.

When pressurizing the escape space in case of a fire and by means of an arrangement in accordance with an embodiment of this invention, the following steps are to be performed:

- starting the fan unit through a signal which is received from a sensor unit detecting a fire, so that the fan unit draws air from outside the escape space, into the air flow directing device, through this device and into the escape space; and - controlling the overpressure generated by the fan unit by means of the damper unit which is closed during an accepted pressure level and which opens when the overpressure exceeds a maximum pressure level.

For evacuation of smoke, the operation of the fan unit may be reversed so that smoke is drawn out from the escape space.

The inventive concept and thereby the various arrangements described above, may be used in several environments such as multi-storey buildings but also on ships, for instance cruise ships which have many floors and usually a lot of passengers to evacuate in case of a fire. The concept can also be applied to mine shafts where fires and explosions may occur and where the workers need a safe evacuation route.

It should be appreciated that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the description is only illustrative and changes may be made in detail, especially in matters of shape, size and arrangement of parts within the scope of the invention to the full extent indicated by the appended claims. For instance, the housing of the damper unit may have other shapes, such as circular. Furthermore, the air flow directing device may be of alternative shape and size. Various partitions may be provided within this device in order to obtain the aimed-at air flow within the same and also to define chambers which preferably are at least partially formed by the fan unit and the damper unit. In the duct system embodiments, the air flow directing device can also have an outer housing with one or more inspection hatches. Various inspection hatches may also be provided in the different casing embodiments.