Fire alarm system

Abstract

 A fire alarm system comprises a control panel 10 and a plurality of detectors 13,14,15 connected to the control panel 10, each detector comprising a sensor 16,18,20 for activating the detector when heat and/or smoke is detected and test means 17,19,23 for stimulating the sensor to activate the detector. The control panel comprises means 40 for actuating the test means eg 17 of a detector 13 and means 41 for providing an indication of whether the detector 13 has and/or has not been activated in response to stimulation by the test means. The control panel can thus remotely test each detector without the need for an engineer to locate or visit each detector.

Description

[0001] This invention relates to a fire alarm system.

[0002] Fire alarm systems are well known which comprise a plurality of heat and/or smoke detectors connected across one or more pairs of wires extending from the control panel. The detectors are able to sense the presence of heat and/or smoke when activated and to provide an indication to the control panel: this then triggers and alarm condition at the control panel which activates one or more audible warning devices or so-called sounders.

[0003] Since the operation fire alarm systems is partially dependent on the correct functioning of the detectors, there is a need to periodically detect each detector. Indeed, there is a legal requirement in the UK that detectors should be tested on a regular basis.

[0004] Typically testing is carried out by setting the control panel into a test mode. An engineer then visits each detector in turn and applies heat or smoke to the detector using an artificial source. This then activates the detector: the detector may omit the visible indication when it is activated. Another engineer with a two-way radio can then examine the control panel to determine whether or not the detector has triggered an alarm condition. This process is then repeated for each detector.

[0005] A disadvantage of this process is that it is disruptive to the occupants of the building in which the detectors are located. Furthermore, some of the detectors may be inaccessible, for example because they are located in a locked rooms or apartments. Other detectors may be hidden from view or mounted in an out-of-reach location.

[0006] WO2006/064190 discloses a synthetic smoke generator which, in one embodiment, is mounted on a pole and can be used by an engineer in the aforementioned manner to activate each detector in turn. In another perceived embodiment, the smoke generator could be mounted at a fixed location adjacent the detector. The website of the company marketing this product discloses that the fixed generator could be activated remotely via wall-mounted socket positioned in the facility of the detector (see http://www.detectortesters.com/site/library/news/Scorpionnews.html). This arrangement is complex in construction, costly to install and still does not solve the above-mentioned problems of disruption and inaccessibility.

[0007] We have now devised an alarm system which alleviates the above-mentioned problems.

[0008] In accordance with the present invention, there is provided a fire alarm system comprising a control panel and a plurality of detectors connected to the control panel, each detector comprising a sensor for activating the detector when heat and/or smoke is detected and test means for stimulating the sensor to activate the detector, the control panel for comprising means for actuating the test means of a detector and means for providing an indication of whether the detector has and/or has not been activated in response to stimulation by said test means.

[0009] In use, the control panel can thus remotely test each detector without the need for an engineer to locate or visit each detector. In this manner, the above-mentioned problems are alleviated.

[0010] Preferably the sensor and the test means are mounted inside an external housing of the detector.

[0011] The test means may comprise a smoke generator or a heat generator mounted adjacent the sensor of the detector. Alternatively, the test means may comprise means for increasing the amount of light incident on a photo sensor disposed inside an optical smoke-sensing chamber of the detector: This may be achieved by actuating a member to extend into the chamber, thereby increasing the amount of light which is reflected towards the photo sensor. The member may be actuated by an electro-mechanical device such as a solenoid.

[0012] The actuating means of the control panel preferably actuates the test means of each detector either in turn or simultaneously in a test routine. The actuating means of the control panel may be arranged to initiate the test routine periodically. Alternatively, the control panel may comprise an actuator which performs the test routine when actuated by an engineer or other person.

[0013] In an alternative embodiment, the actuating means of the control panel is arranged to actuate the test means of successive detectors when the actuating means is successively actuated by an engineer or other person.

[0014] The actuating means may be arranged for remote actuation, for example via the internet or a wireless connection.

[0015] The indication means of the control panel may be arranged to provide an audible and/or visible indication only if all of the detectors are activated. The indication may be provided by triggering with the control panel into an alarm condition. Preferably the control panel is arranged to inhibit sounders of the alarm system whilst the detectors are tested, so as not to disturb the occupant

[0016] The indication means preferably provides an indication of which detectors have not been activated. In this regard, each detector preferably comprises an address code, the control panel being arranged to determine the address code of the detectors which have and/or not been activated by said stimulation.

[0017] Preferably the indication means is arranged to log whether the detectors have and/or not been activated in response to said stimulation by said test means. The log may only show or highlight detectors which have not been activated.

[0018] Preferably the log can be stored or printed to provide evidence that the system has been tested.

[0019] Also in accordance with the present invention, there is provided a method of testing a fire alarm system comprising a control panel and a plurality of detectors connected to the control panel, each detector comprising a sensor for activating the detector when heat/or smoke is detected and test means for stimulating the sensor to activate the detector, the method comprising actuating the control panel to cause said test means to stimulate a detector and determining at the control panel whether the detector has and/or has not been activated.

[0020] The stimulation may be provided by applying heat or smoke to the sensor or by increasing the amount of light incident on a photo sensor disposed inside an optical smoke-sensing chamber of the detector.

[0021] An embodiment of the present invention will now be described by way of an example only and with reference to the accompanying drawings, the single figure of which is a schematic block diagram of a fire alarm system in accordance with the present invention.

[0022] Referring to the drawing, there is shown a control panel 10 of a fire alarm system. A pair of wires 11, 12 extend from the control panel 10 and a plurality of detectors, e.g. 13, 14 and 15 are connected in parallel across the wires 11, 12.

[0023] The detector 13 comprises a heat sensor 16 such as a thermistor and a heat generating device 17 mounted below the sensor 16. The heat generating device 17 may comprise a resistor or a coil.

[0024] The detector 14 comprises a smoke sensor 18 and a smoke generator 19 mounted below the sensor 18. The smoke generator 19 may generate synthetic smoke or it may generate actual smoke, for example by heating or burning a material such as a hydrocarbon. Other kind of smoke generators may be used which will be readily apparent to those skilled in the art.

[0025] The detector 15 comprises an optical smoke-sensing chamber 20 which is provided with an optical emitter 21 and a photo sensor 22. The detector 15 is activated when smoke particles inside the chamber 20 cause an increase in the amount of light emitted by the emitter 21 reaching the photo sensor 22. A solenoid 23 or other electro-mechanical actuation device is mounted adjacent the optical smoke-sensing chamber 20. The solenoid 23 comprises a moveable armature 24 which extends into the chamber 20 when the coil of the solenoid 23 is activated. The movable armature 24 of the solenoid 23 is formed of an optically reflective material, which thus increases the amount of light reflected towards the photo sensor 22, thereby simulating the presence of smoke.

[0026] The control panel 10 comprises a test circuit 40 which sends a coded test signal to each detector e.g. 13, 14, 15 in turn. Upon receipt of the signal, the detector 13 energises the heat generating device 17: the excess heat is sensed by the heat sensor 16 and the detector 17 activates into an alarm condition. The alarm condition is then registered in a logging circuit 41 of the control panel 10. In the event that the detector 13 is not activated in response to the test signal, then this is also recorded in the logging circuit 41.

[0027] A similar process is then carried out for each detector eg 14, 15 in turn. In the case of the detector 14, the smoke generator 19 is actuated to cause smoke to be sensed by the sensor 18. In the case of the detector 15, the solenoid 23 is actuated, in order to cause the moveable armature 24 to extend into the optical-smoke chamber 20.

[0028] The above-mentioned test procedure may be initiated at regular intervals by a timer control device disposed inside the control panel 10. Alternatively, it may be initiated by actuating a manual control device, such as a button 43 disposed on the control panel 10. The control panel 10 may also be connected to a communications network 42, so that the test routine can be initiated remotely.

[0029] The logging circuit 41 provides an indication of which detectors e.g 13, 14, 15 have and/or not been activated by the test routine. This indication may be provided by a visual display panel (not shown) provided on the control panel 10. Alternatively, the logging circuit 41 can be interrogated by an external device, such as a laptop computer connected directly to the control panel or connected via the network 42.

[0030] Whilst the fire alarm system described herein has been described as comprising three different types of detector e.g. 13, 14, 15 it will be appreciated that this is purely illustrative and that only detectors of one or two types may be present in any alarm system.

[0031] An alarm system in accordance with the present invention thus reliably enables detectors to be detected on a regular basis without the need to physically access each detector in turn. In this manner, the problems associated with causing disturbance and accessing the detectors is alleviated.

Claims

1. A fire alarm system comprising a control panel and a plurality of detectors connected to the control panel, each detector comprising a sensor for activating the detector when heat and/or smoke is detected and test means for stimulating the sensor to activate the detector, the control panel comprising means for actuating the test means of a detector and means for providing an indication of whether the detector has and/or has not been activated in response to stimulation by said test means.

2. A fire alarm system as claimed in claim 1, in which the sensor and the test means are mounted inside an external housing of the detector.

3. A fire alarm system as claimed in claim 1 or claim 2, in which the test means comprises a smoke generator mounted adjacent the sensor of the detector.

4. A fire alarm system as claimed in claim 1 or claim 2, in which the test means comprises a heat generator mounted adjacent the sensor of the detector.

5. A fire alarm system as claimed in claim 1 or claim 2, in which the test means comprises means for increasing the amount of light incident on a photo sensor disposed inside an optical smoke-sensing chamber of the detector:

6. A fire alarm system as claimed in claim 5, in which the amount of light incident on a photo sensor is increased by actuating a member to extend into the chamber, thereby increasing the amount of light which is reflected towards the photo sensor.

7. A fire alarm system as claimed in any preceding claim, in which the indication means is arranged to log whether the detectors have and/or not been activated in response to said stimulation by said test means.

8. A method of testing a fire alarm system comprising a control panel and a plurality of detectors connected to the control panel, each detector comprising a sensor for activating the detector when heat/or smoke is detected and test means for stimulating the sensor to activate the detector, the method comprising actuating the control panel to cause said test means to stimulate a detector and determining at the control panel whether the detector has and/or has not been activated.

9. A method as claimed in claim 8, in which the stimulation is provided by applying heat to the sensor.

10. A method as claimed in claim 8, in which the stimulation is provided by applying smoke to the sensor.

11. A method as claimed in claim 8, in which the stimulation is provided by increasing the amount of light incident on a photo sensor disposed inside an optical smoke-sensing chamber of the detector.

Drawing