FIRE DETECTION FOR DIRTY ENVIRONMENTS

Abstract

A fire detector for monitoring an environment and a method of operating a fire detector including a smoke sensor and a volatile organic compound, VOC, sensor are described. A fire detector 10 for monitoring an environment 20 includes a smoke sensor 12 and a volatile organic compound, VOC, sensor 14, the fire detector 10 is configured to adjust a smoke sensitivity of the fire detector 10 based on a VOC concentration detected by the VOC sensor 14. The smoke sensitivity is decreased when increased VOC concentrations are detected.

Claims

1. A fire detector (10) for monitoring an environment (20), the fire detector comprising a smoke sensor (12) and a volatile organic compound, VOC, sensor (14), wherein the fire detector is configured to adjust a smoke sensitivity of the fire detector based on a VOC concentration detected by the VOC sensor.

2. A fire detector (10) according to claim 1, wherein the fire detector is configured to take an action responsive to detection of a concentration of smoke exceeding a smoke threshold, wherein the smoke threshold is determined as a function of the VOC concentration detected by the VOC sensor (14).

3. A fire detector (10) according to claim 2, where the fire detector is configured such that a first, lower smoke threshold is used as the smoke threshold when a VOC concentration detected by the VOC sensor (14) is below a first VOC threshold, and a second, higher smoke threshold is used as the smoke threshold when the VOC concentration detected by the VOC sensor is above the first VOC threshold.

4. A fire detector (10) according to claim 2, wherein the action comprises sending an alert to a fire control panel.

5. A fire detector (10) according to claim 2, wherein the action comprises triggering a perceivable alarm or triggering a fire protection system and/or a fire suppression system associated with the monitored environment (20).

6. A fire detector (10) according to claim 1, wherein the VOC sensor (14) comprises a multi-gas sensor configured to detect environmental data comprising a concentration of at least one of PM2.5 particles, CO2 gas and H2 gas, and wherein the fire detector (10) is configured to send the environmental to an external system.

7. A fire detector (10) according to claim 1, wherein the fire detector is a point-type fire detector.

8. A fire response system comprising a fire detector (10) according to claim 1 and a fire control panel in communication with the fire detector.

9. A fire response system according to claim 8, wherein the fire detector (10) is one of a plurality of fire detectors, and wherein the fire response system further comprises one or more of an alarm, a fire protection system and a fire suppression system.

10. A method of operating a fire detector (10) comprising a smoke sensor (12) and a volatile organic compound, VOC, sensor (14), the method comprising: monitoring a concentration of VOCs within an environment (20) using the VOC sensor; and adjusting a smoke sensitivity of the fire detector based on the VOC concentration.

11. A method according to claim 10, wherein the method comprises: taking an action responsive to detection of a concentration of smoke exceeding a smoke threshold, wherein a first, lower smoke threshold is used as the smoke threshold when a VOC concentration detected by the VOC sensor (14) is below a first VOC threshold, and wherein a second, higher smoke threshold is used as the smoke threshold when the VOC concentration detected by the VOC sensor is above the first VOC threshold.

12. A method according to claim 11, wherein the action comprises one or more of: triggering a perceivable alarm. triggering a fire protection system and/or a fire suppression system; and sending an alert to a fire control panel.

13. A method according to claim 10, further comprising: detecting environmental data using the VOC sensor (14), wherein the environment data comprises at least one of a concentration of PM2.5 particles, a concentration of CO2 gas and a concentration of H2 gas; and sending environment data to an external system separate from the fire detector.

14. A computer program product or a tangible computer readable medium storing a computer program product, wherein the computer program product comprises computer executable instructions that when executed will cause a fire detector (10) to perform a method according to claim 10.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] A preferred embodiment of the present disclosure will now be described in greater detail, by way of example only and with reference to the accompanying figures, in which:

[0045] FIG. 1 shows a fire detector.

DETAILED DESCRIPTION

[0046] FIG. 1 shows a point-type fire detector 10 comprising a smoke sensor 12 and a multi-gas sensor 14. The smoke sensor 12 and the multi-gas sensor 14 are connected to a controller 16, which serves to control the operation of the fire detector 10.

[0047] The fire detector 10 is configured to be positioned within an environment 20 that it is desired to monitor, such as a room or space within a building. Ambient movement of air within the environment 20 causes air samples to be supplied to the fire detector 10, and the controller 16 uses the sensors 12, 14 to examine the air samples for indicators of fire within the environment 20.

[0048] In this embodiment, the fire detector 10 is configured to be connected, for example by a wired connection, to a fire control panel of a fire response system associated with the building. In the event of the detection of the presence of fire within the environment 20, the controller 16 sends an alert to the fire control panel, which may take appropriate action.

[0049] The fire response system may comprise one or more audible or visible alarm to alert occupants of the need to evacuate, which may be triggered in response to the detection of fire by the fire detector 10. The fire response system may further comprise one or more fire protection system and/or a fire suppression system, and one or more of these systems associated with the monitored environment 20 may be activated in responsive to the detection of fire by the fire system 10.

[0050] Those familiar with this field of technology will be well aware of the functionality and operation of such fire response systems, and these will therefore not be discussed in detail.

[0051] The controller 16 of the fire detector 10 detects the presence of fire within the monitored environment 20 by comparing a concentration of smoke detected by the smoke sensor 12 to a smoke threshold. If the concentration of smoke exceeds the smoke threshold, then the fire detector 10 sends the alert as described above. If the concentration of smoke does not exceed the smoke threshold, then no alert is sent.

[0052] The fire detector 10 is particularly designed for use within a dirty environment, such as a warehouse, a factory, an automotive parking facility or the like. These environments commonly include automotive vehicles or machinery comprising engines that burn fossil fuel and emit emissions that may contain smoke.

[0053] In order to reduce the risk of false alarms caused by these emissions, the gas sensor 14 is used to monitor for the presence of volatile organic compounds (VOCs) within the monitored environment 20. The presence of VOCs indicates the likely presence of emissions within the environment 20, and consequently the smoke sensitivity of the fire detector 10 is reduced in these situations.

[0054] In order to reduce the smoke sensitivity of the fire detector 10, the smoke threshold used by the controller 16 is increased. In one embodiment, when the total concentration of VOCs is below a VOC threshold, indicating low VOC levels, then the controller 16 will use a first, relatively low smoke threshold, and when the total concentration of VOCs is above the VOC threshold, indicating high VOC levels, then the controller 16 will use a second, relatively high smoke threshold.

[0055] By operating the controller in this manner 16, the fire detector 10 can still be operated in a high sensitivity mode when low VOC levels are detected, which provides an early indication of fire within the environment 20. However, the fire detector can nevertheless avoid, or at least reduce the number, of false alarms that might otherwise be caused by emissions within the environment 20.

[0056] Optionally, the controller may employ a plurality of different smoke thresholds, where the smoke threshold is progressively increased as the total concentration of VOCs increases past successively increasing VOC thresholds. In this way, the smoke sensitivity of the fire detector 10 changes in a more gradual manner within changing VOCs, thereby allowing increased smoke sensitivity when medium levels of VOCs are present, which would indicate the presence of somewhat increased smoke levels from emissions, but not necessarily high levels of smoke from emissions.

[0057] The smoke sensor 12 is an optical smoke sensor comprising a detection chamber, a light source and a light detector. Typically, the light source would be an infra-red (IR) LED or laser, and the light detector would be a photo-diode.

[0058] The smoke sensor 12 operates on a light scattering principle. The light source is configured to emit light into the detection chamber and the light detector is configured to detect light scattered by the smoke.

[0059] The fire detector 10 comprises a housing 18 provided within an optical labyrinth, which is configured to permit the flow of air into the detection chamber, but to prevent the direct transmission of light from the environment 20 into the detection chamber.

[0060] The gas sensor 14 is a metal oxide gas sensor, which is configured to detect the presence of various gases within air sampled from the monitored environment. In one embodiment, the gas sensor 14 may be an SGP30 sensor manufactured by Sensirion. The gas sensor 14 may be provided within the housing 18, for example within the detection chamber of the smoke sensor 12, but may alternatively be positioned outside of the housing 18 and exposed into the environment 20.

[0061] In various embodiments, the controller 16 may monitor the concentrations of one or more further components of the air sampled from the environment 20. These may include a concentration of CO2, a concentration of H2 and a concentration of PM2.5 particles. These concentrations may be indicative of air quality within the monitored environment 20.

[0062] The controller 16 may be configure to transmit environmental data to the fire control panel, or another system, where the environmental data comprises one or more of a total concentration of VOCs, a concentration of CO2, a concentration of H2 and a concentration of PM2.5 particles. This data may permit analysis of the air quality of the monitored environment. For example, if poor air quality is detected, a maintenance alert may be triggered to prompt a service provider to investigate the cause of the poor air quality within the monitored environment 20.

[0063] Advantageously, but utilising the environmental data collected by the gas sensor 14, it is possible to avoid the need for a separate environmental monitoring device within the monitored environment 20.

[0064] A further advantage of this type of gas sensor 14, is that it may additionally be operated to detect the presence of smoke. Indeed, it has been found that the gas sensor 14 has a higher sensitivity to smoke that many types of optical smoke detectors, such as used as the smoke sensor 12. Consequently, in some embodiments, the gas sensor 14 may be used to also detect the concentration of smoke within the monitored environment 20. This can either supplement the smoke detector 12, or indeed may be used as the smoke detector 12.

[0065] In one example, the gas sensor 14 may be used for the detection of smoke when low levels of VOC are present, i.e. when the fire detector 10 is operating at a high sensitivity, and the optical smoke sensor 12 may be used for the detection of smoke when high levels of VOC are present, i.e. when the fire detector 10 is operating at a low sensitivity.

[0066] Whilst a limited number of embodiments have been described, it will be appreciated that the techniques described herein may be applied to any type of fire detector 10. For example, the fire detector 10 is shown as a point-type detector, but the techniques described herein may also be applied to aspirating fire detectors. Furthermore, whilst the illustrated fire detector 10 is described as being for use with a fire response system of a building, the techniques described herein may also be applied to self-contained fire detectors having their own alarm system or where the fire detector directly triggers an external alarm system, fire suppression system or fire control system.