Aspiration smoke detection system

Abstract

An aspiration smoke detection system for detecting the presence of a fire within a region of interest. The aspiration smoke detection system includes a smoke detection unit for detecting the presence of smoke particles suspended in air; and one or more local sensors located remotely from the smoke detection unit for measuring a property of air from the region of interest that is drawn into the aspiration smoke detection system. An inlet piece includes a sensor for use with the aspiration smoke detection system is also provided. A method of detecting a fire using the aspiration smoke detection system and a method of locating a fire using the aspiration smoke detection system are also provided.

Claims

1. An aspiration smoke detection system for detecting the presence of a fire within a region of interest, the aspiration smoke detection system comprising: a smoke detection unit comprising a smoke detector housed within a sampling chamber for detecting the presence of smoke particles suspended in air within the sampling chamber; and one or more local sensors located remotely from the smoke detection unit for measuring a property of air from the region of interest that is drawn into the aspiration smoke detection system; wherein the aspiration smoke detection system is configured to pass air from the region of interest to the sampling chamber of the smoke detection unit via one of the one or more local sensors, and wherein the aspiration smoke detection system is configured to use the one or more local sensors to detect quick developing fires before a sample of air reaches the sampling chamber of the smoke detection unit.

2. An aspiration smoke detection system according to claim 1, wherein the smoke detection unit is more sensitive than the one or more local sensors.

3. An aspiration smoke detection system according to claim 1, wherein the local sensor is for measuring one or more of: the rate of temperature change of the air, the presence of smoke particles suspended in the air, and the presence of carbon dioxide in the air.

4. An aspiration smoke detection system according to claim 1, wherein the system comprises a controller, wherein the controller is arranged to receive data collected by the smoke detection unit and the one or more local sensors.

5. An aspiration smoke detection system according to claim 4, wherein the controller is configured to raise an alarm if the concentration of smoke particles suspended in the air measured by the smoke detection unit is above a predetermined threshold value.

6. An aspiration smoke detection system according to claim 4, wherein the controller is configured to raise an alarm if data from one or more of the local sensors measures a property of the air that is indicative of a fire.

7. An aspiration smoke detection system according to claim 4, wherein if the data from the smoke detection unit is indicative of a fire being present in the region of interest, the controller is configured to determine the most likely location of a fire within the region of interest based on data collected by the local sensors.

8. An aspiration smoke detection system according to claim 1, wherein the local sensors are configured to continuously monitor the air drawn into the aspiration smoke detection system from the region of interest.

9. An aspiration smoke detection system according to claim 1, wherein the local sensors are configured to periodically monitor the air drawn into the aspiration smoke detection system from the region of interest.

10. An aspiration smoke detection system according to claim 1, comprising one or more inlets for passing air from the region of interest into the smoke detection unit.

11. An aspiration smoke detection system according to claim 10, wherein the one or more local sensors are each located on, near or in one of the inlets.

12. An aspiration smoke detection system according to claim 10, wherein the transport time of air from at least one of the inlets to the smoke detection unit is greater than 70 seconds, or greater than 100 seconds.

13. An aspiration smoke detection system according to claim 10, wherein the distance a sample has to travel between one or more of the inlets and the smoke detection unit is greater than 50 m, or greater than 100 m, or greater than 200 m.

14. A method of detecting a fire within a region of interest using an aspiration smoke detection system, the method comprising: providing the aspiration smoke detection system of claim 1; passing air from the region of interest to the sampling chamber of the smoke detection unit via one of the one or more local sensors; using the smoke detector of the smoke detection unit to measure a concentration of smoke particles within the air that has been passed to the sampling chamber of the smoke detection unit; using the one or more local sensors to measure a property of the air that can be used to indicate the presence of a fire; determining if the concentration of smoke particles measured by the smoke detector of the smoke detection unit is indicative of a fire within the region of interest; and/or determining if the measured property of air sensed by the one or more local sensors is indicative of a fire within the region of interest; wherein the local sensors are used to measure a property of the air before the air reaches the sampling chamber of the smoke detection unit in order to detect quick developing fires before the air reaches the smoke detection unit.

15. A method according to claim 14, wherein the local sensors are used to continuously monitor the air drawn into the aspiration smoke detection system from the region of interest.

16. A method according to claim 14, wherein the local sensors are used to periodically monitor the air drawn into the aspiration smoke detection system from the region of interest.

17. A method according to claim 14, wherein the transport time for the air from at least one of the local sensors to the smoke detection unit is greater than 70 seconds, or greater than 100 seconds.

18. A method of detecting a fire within a region of interest using an aspiration smoke detection system, wherein the aspiration smoke detection system is the aspiration smoke detection system of claim 1.

19. A method of retrofitting one or more local sensors to an existing aspiration smoke detection system to provide the aspiration smoke detection system of claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Certain preferred embodiments of the present invention will now be described, by way of example only, with reference to the following drawings, in which:

(2) FIG. 1 shows a schematic of an aspiration smoke detection system; and

(3) FIG. 2 shows a cross section through an inlet piece that may be used with the aspiration smoke detection system of FIG. 1.

DETAILED DESCRIPTION

(4) FIG. 1 shows an aspiration smoke detection system 1 capable of detecting the presence of a fire within a region of interest, for instance one or more rooms 16a, 16b, 16c of a building. The system 1 comprises a central detection unit 2 and a sampling pipe 3 extending from the central detection unit 2 for enabling air from the region of interest to be passed to the central detection unit 2. A fan, for example, may be used to draw air into the sampling pipe 3 from the region of interest and pass it to the central detection unit 2. In the exemplary embodiment in FIG. 1, the system 1 is shown located and arranged within a ceiling void above several rooms 16a, 16b, 16c in a building in order to detect smoke emanating from within one or more of the rooms 16a, 16b, 16c. However, the aspiration smoke detection system 1 may be used in any location to detect the presence of a fire in a region of interest.

(5) The central detection unit 2 includes a sampling chamber 5 (shown by the dashed line in FIG. 1) that is fluidly connected to the sampling pipe 3. The sampling chamber 5 houses a smoke detector for detecting the presence of smoke particles suspended in the air within the sampling chamber 5. The smoke detector may for example be a nephelometer, or any other known smoke detector. The central detection unit 2 also includes a controller 15 for controlling operation of the smoke detection system 1 and/or for processing data from the system 1. The controller 15 is connected to the smoke detector such that data acquired by the smoke detector can be passed to the controller 15 for further processing.

(6) The smoke detector is highly sensitive and able to detect the presence of smoke particles suspended in the air within the sampling chamber 5 even when the concentration of smoke particles is low, for example below 0.03% obs/m (0.01% obs/ft) or below 0.015% obs/m (0.005% obs/ft). This means that the smoke detector may be able to detect the existence of slowly developing smouldering fires during the early stages of such fires, e.g. before flames are present.

(7) The sampling pipe 3 has a plurality of inlets 4 along its length to allow air and smoke particles to enter the sampling pipe 3. To enable the system 1 to detect the presence of smoke in each of the rooms 16a-c within the region of interest, the inlets 4 are arranged along the sampling pipe 3 such that air and smoke can enter the system 1 from each room 16a-c via at least one inlet 4. For example, one, two, a plurality or more inlets 4 may be located in the sampling pipe 3 above each room 16a-c. Whilst the present example has a plurality of inlets 4 for detecting the presence of smoke in a plurality of rooms, it will be appreciated that the system 1 may only have one inlet 4, for example where the region of interest includes a single room or other undivided area.

(8) Each of the inlets 4 is fluidly connected to an inlet piece 6 by flexible tubing 7. Whilst in this example flexible tubing 7 is used to fluidly connect an inlet 4 to an inlet piece 6, it will be appreciated that any suitable fluid connection may be used. For example, a rigid fluid connection may be used.

(9) An inlet piece 6 that may be used with the system 1 of FIG. 1 is shown in more detail in FIG. 2. Each inlet piece 6 includes an inlet pipe 8 having a capillary sampling port 9 arranged at a first end 10 of the inlet pipe 8. The sampling port 9 allows air and smoke particles to enter the inlet pipe 8 and subsequently pass to the sampling pipe 3. In this example, a flange 12 is provided at the first end 10 for facilitating mounting of the inlet piece 6 within the region of interest. For example, the inlet piece 6 may be mounted to a ceiling panel 13 of a room 16a-c by attaching the flange 12 to the ceiling panel 13. A second end 11 of the inlet pipe 8 is for connection to one of the inlets 4 of the sampling pipe 3 via the flexible tubing 7, thereby fluidly connecting the inlet piece 6 to the sampling pipe 3.

(10) With this arrangement, it is possible for air (and smoke particles when present) within each of the rooms 16a-c to be drawn into the sampling pipe 3 by passing consecutively through a sampling port 9, an inlet pipe 8 and a flexible tube 7. The air, along with any smoke particles suspended in the air, is then able to pass (e.g. driven by a fan) via the sampling pipe 3 to the sampling chamber 5 of the central detection unit 2.

(11) As shown in FIG. 2, each inlet piece 6 is provided with a local sensor 14 within the inlet pipe 8 adjacent the sampling port 9. The one or more local sensors 14 may for example be rate-of-rise temperature sensors for monitoring the change of temperature within a room. Rate-of-rise temperature sensors are able to detect rapid increases in temperature that may be indicative of the presence of a fire within a room by measuring the rate at which a sensed temperature rises. The one or more local sensors 14 are connected to the controller 15 of the central detection unit 2 to allow data acquired by the local sensors 14 to be passed to the controller 15 for further processing.

(12) The local sensors 14 are less sensitive than the smoke detector housed in the central detection unit 2. Each of the local sensors 14 may be capable of quickly detecting the presence of a quickly developing, highly exothermic fire in the region of interest that releases a large quantity of heat and/or smoke over a relatively small amount of time. In fact, the local sensors 14 may be able to detect this type of fire before the central detection unit 2 because of the smaller distance between the local sensor 14 and the fire compared to the distance between the central detection unit 2 and the fire.

(13) However, the local sensors 14 may not be able to quickly detect the presence of a slowly developing smouldering fire which initially gives off only a small amount of heat and smoke due to the lesser sensitivity. Instead, the system 1 can rely on the highly sensitive smoke detector within the central detection unit 2 to detect the presence of such a slowly developing fire. The extra time for the slowly developing smouldering fire to be detected because of the longer distance between the central detection unit 2 and the fire is acceptable for such slow developing fires. However, in such a circumstance, when a fire has been detected by the central detection unit 2 but not by the local sensors 14 (and in a system with a plurality of local sensors 14), data from the plurality of local sensors 14 may still be used to determine where the fire is most likely to be located. For example, the data from the local sensors 14 may be analysed to determine whether any of them have shown small changes in the sensed condition that may suggest that local sensor 14 is closest to the fire. This may allow the location of the fire to be determined more quickly even if the local sensors 14 are not sensitive enough to actually detect the fire directly.

(14) Whilst in this example the one or more local sensors 14 are each located in the one or more inlet pieces 6, the one or more local sensors may be in any location remote from the central detection unit 2 that is closer to the region of interest e.g. in a location that allows the local sensor 14 to measure a property of air as it is drawn into the system 1. The fact that the system 1 comprises a central smoke detection unit 2 and one or more local, less sensitive sensors 14 which are closer to the region of interest may be more important than the precise location of the one or more local sensors 14.

(15) The operation of the smoke detection system 1 will now be described with reference to FIGS. 1 and 2.

(16) The presence of a fire or the start of a fire in one or more of the rooms 16a-c in the region of interest generates smoke and/or heat. Air (and smoke where present) from each of the rooms 16a-c in the region of interest is drawn into the system 1 through the sampling ports 9, e.g. aided by the action of the fan. The air then passes through the corresponding inlet piece 6 and flexible tubing 7 to the sampling pipe 3. In the sampling pipe 3 the air from each of the sampling ports 9 is combined and mixed, and passed to the sampling chamber 5 of the central detection unit 2.

(17) Within the central detection unit 2 (e.g. in the sampling chamber 5 in the central detection unit 2), the smoke detector is used to determine the concentration of smoke particles suspended in the air. The smoke detector constantly monitors the air in the sampling chamber 5 to determine if smoke particles are present. The smoke detector acquires information about the concentration of smoke particles in the air, and this smoke concentration data is passed to the controller 15 for further processing.

(18) The heat generated by the fire (or some other parameter) will also be sensed by one or more of the local sensors 14. Each of the local sensors 14 may constantly or periodically monitor the air from a particular room 16a-c and generate data about the air, e.g. the rate at which the temperature changes. The data generated by the local sensors 14 may indicate how the temperature of the rooms 16a-c fluctuates over time. This data from the one or more local sensors 14 is also passed to the controller 15 for further processing.

(19) The controller 15 analyses the smoke concentration data and the data acquired respectively by the smoke detector and the local sensors 14 to determine if a fire is present within one or more of the rooms 16a-c in the region of interest. If the smoke concentration data indicates that the concentration of smoke particles in the sampled air is above a predefined threshold limit, for example 0.3% obs/m (0.1% obs/ft), the controller 15 determines that a fire is present in one of the rooms 16a-c and may trigger an alarm and/or an alert.

(20) In addition, the controller 15 may be able to determine the most likely location of the fire by analysing the data from the local sensors 14. For example, the heat generated by the fire may cause the temperature in one or more of the rooms 16a-c to increase. As a result, the data acquired by one or more of the local sensors 14 may be representative of this increase in temperature. That is to say, if the temperature in a room 16a-c increases by a certain amount, the data acquired by the local sensor 14 situated in that room 16a-c may also deviate. This deviation may be too small for it to be determined that a fire has started but once a fire has been detected by the central detector 2, is sufficient to suggest that local sensor 14 is the one closest to the detected fire. For example, the controller 15 may determine which of the local sensors 14 has the greatest deviation in the sensed data. This local sensor 14 is determined to be the one most likely to be the closest to the fire. Therefore, the controller 15 identifies this local sensor 14 as being located at the most likely location of the fire. Since the locations of the local sensors 14 are known, the controller 15 is able to identify the most likely location of the fire. This may help speed up the location determination of a fire which has been detected using an aspiration smoke detection system 1, particularly a system 1 that monitors a large region of interest.

(21) The system 1 may also able to detect the presence of a fire based on the data acquired by the local sensors 14.

(22) If one of the local sensors 14 senses a change in the sensed data that is above a predefined threshold, the controller 15 determines that a fire is present at the location of the particular local sensor 14 and raises an alarm and/or alert. For example, if the local sensors 14 comprise temperature sensors, if one of the local sensors 14 senses a rate of increase in temperature that is above a predefined threshold, for example above 6° K./minute or above 8° K./minute, the controller 15 may determine that a fire is present at the location of the particular local sensor 14 and may raise an alarm and/or alert.

(23) The combination of the highly sensitive smoke detector housed in the sampling chamber 5 and the less sensitive local sensors 14 allows the system 1 to be able to quickly detect and alert people to the presence of different types of fires and also allows the system to identify a likely location of these fires within the region of interest. As discussed above, slowly developing smouldering fires initially generate low levels of heat and smoke. The local sensors 14 may not be sensitive enough to detect the presence of such a fire, at least initially, and the fire is instead detected by the central smoke detector due to the increased concentration of smoke particles suspended in the air passed to the central detection unit 2.

(24) The presence of quickly developing exothermic fires, e.g. flaming polyurethane, may be detected quickly by the local sensors 14 due to the large, fast change in parameters, e.g. rapid increase in temperature, caused by such fires. Since the system 1 can identify the presence of quickly developing exothermic fires without the need for air to be passed to the sampling chamber 5, the time taken by the system 1 to detect such fires is not limited by the transportation time and hence may be quicker than the transportation time.

(25) Moreover, the presence of the local sensors 14 also enables the system 1 to indicate the location of a fire within the region of interest. In the case of a slowly developing smouldering fire, whilst the local sensors 14 may not be able to determine the presence of such a fire, if the fire is close to a local sensor 14 it may cause the local sensor 14 to register a variation in data, e.g. increase in temperature. This data is used by the controller 15 to determine the most likely location of the fire detected by the central smoke detector 2.

(26) The local sensors 14 also provide the system 1 with information about the location of quickly developing exothermic fires that are detected by one or more of the local sensors 14.

(27) Hence, the aspiration smoke detection system 1 ensures that quickly developing exothermic fires as well as slowly developing smouldering fires can be detected quickly to meet safety certification standards. The aspiration smoke detection system 1 may also ensure that the location of a fire, the presence of which is detected by the system 1, can be identified quickly.