EP3510325A1

EP3510325A1 - Safety system

Info

Publication number: EP3510325A1
Application number: EP17761110.0A
Authority: EP
Inventors: Stephen George IREDALE; Stephen John MORGAN
Original assignee: Individual
Current assignee: Individual
Priority date: 2016-09-07
Filing date: 2017-08-18
Publication date: 2019-07-17
Also published as: WO2018046882A1; GB2539830A; GB201615225D0; GB2539830B

Abstract

The invention relates to a safety system for use in relation to an installation in a building (10) comprising an appliance (18, 20) fuelled with combustible material through a supply line (16). The safety system comprises: an electrically operable valve (34) for incorporation in the supply line, at least one detector (22, 24) responsive to conditions indicative of fire in the building, at least one electrically operable valve (34) for incorporation into the supply line, the valve being closable to shut-off fuel flow through the supply line, and a controller (28) configured to receive an emergency signal from the detector upon detection of a fire, and to control the electrically operable valve to close in response to the signal, thereby shutting off fuel flow through the supply line.

Description

SAFETY SYSTEM

The present invention relates to a safety system which is configured to cut off fuel supply to an appliance in the event of fire or other potentially dangerous events. Domestic dwellings and commercial premises often use appliances fuelled by combustible material for heating and other purposes. These include gas-fuelled appliances such as boilers for central heating and/or for water heating, gas cookers and gas fires, but they also include appliances fuelled by other material including biomass, liquid fuel (oil), and liquefied petroleum gas (LPG).

Such appliances can be dangerous under certain circumstances. They can be a cause of fire if mistreated or malfunctioning. Poor combustion conditions, often due to poor maintenance, can result in the appliance emitting harmful gases into the atmosphere of the building, creating a hazard to health. These gases can include carbon monoxide.

Also in the event of fire, whether caused by the appliance in question or not, there is the risk that combustible fuel will escape from the appliance or from its supply line and catch fire itself, which would add to the hazard. Fire services arriving at a building in response to a fire typically make it one of their first tasks to locate the isolating valve in the gas supply, in order to shut off supply of gas to the building.

The building's electricity supply can also pose a danger in the event of fire, and fire services often choose also to locate the building's electrical isolation system (often referred to as the "consumer unit") and to use it to disconnect the building's electrical supply, before taking action to extinguish the fire.

Domestic dwellings often have smoke alarms which detect atmospheric smoke, typically using either an ionisation type detector or an optical detector. Householders can also purchase carbon monoxide detectors to provide an alert of excessive levels of CO in the air. Various commercially available units are able to respond to both smoke and CO. Domestic alarms of this type are often small, essentially self-contained items suitable for ceiling or wall mounting. They are often battery powered but may be connectable to a mains electrical supply. It is known to network domestic smoke alarms in order that activation of one alarm will activate all alarms in the building, and this networking can be made through hard wiring or through a wireless ( F) link. But these self-contained domestic smoke and CO alarm units typically serve only to provide an audible alarm signal, and have no facility for controlling the building's fuel and electrical systems in response to an emergency. DE19524643 (Huberg Gasmesstechnik GmbH) discloses a safety system responsive to detection of levels of oxygen, natural gas, propane and carbon monoxide, having an electrically controllable valve to block a power supply in response to leakage of gas. But there is no recognition in this document of the need to shut down fuel supply in response to a fire. There is a need for a simple safety system capable of detecting emergencies in a building and of responding in a manner which reduces the risk of unintended or inappropriate combustion of fuel.

According to the present invention there is a safety system for use in relation to an installation in a building comprising an appliance fuelled with combustible material through a supply line, the safety system comprising: at least one detector responsive to conditions indicative of fire in the building, at least one electrically operable valve for incorporation into the supply line, the valve being closable to shut-off fuel flow through the supply line, and a controller configured to receive an emergency signal from the detector upon detection of a fire, and to control the electrically operable valve to close in response to the signal, thereby shutting off fuel flow through the supply line, wherein the electrically operable valve is configured to open in response to an applied electrical signal and to close in the absence of said signal, so that in the event of a loss of electrical power to the safety system fuel flow is shut off.

Specific embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:-

Figure 1 is a schematic representation of a gas installation in a building, incorporating a safety system embodying the present invention; Figure 2 is a schematic representation of a gas installation in a building, incorporating a further safety system embodying the present invention;

Figure 3 is a schematic representation of a heating system in a building using an alternative fuel, the heating system incorporating another safety system embodying the present invention;

Figure 4 is a circuit diagram of an electrical supply circuit used in a control unit of a safety system embodying the present invention; and Figure 5 is a circuit diagram of an electrical appliance control circuit used in the same safety system.

The safety systems to be described herein serve to monitor conditions in a building and, in response to detection of conditions indicative of a possible emergency, to shut off a supply of combustible fuel to a fuel-burning appliance in the building.

The installation represented in Figure 1 is disposed in, and serves to protect, a building which is represented by box 10. The building 10 may be a domestic dwelling. It may be a bungalow, house or flat (apartment) although the present invention is also applicable to buildings of other types including commercial premises. In the drawings, dotted lines are used to represent signal connections through which signals are transmitted between one functional unit and another. In the present embodiment these signal connections are made through electrical wiring, although in other embodiments they may be made through other suitable means, including without limitation any form of analogue or digital communications network or bus, which may be hard wired, or may use another tangible data conduit (such as optical fibre), or may be wireless, using radio frequency transmission or transmission by other intangible means.

Supply lines through which combustible fuel is supplied to appliances are indicated in the drawings using unbroken lines. In the installation represented in Figure 1 these are formed as gas pipes.

The installation represented in Figure 1 uses combustible fuel in the form of gas from a mains supply led into the building via a manually operable isolation valve 12, a gas meter 14 and a network 16 of gas pipes running through the building to gas appliances comprising in this example a boiler (water heater) 18 and a gas cooker 20. The boiler may for example be configured to provide hot water for a central heating system, or for a plumbing system, or both. Each of the appliances has its own manual isolation valve 18a, 20a. These aspects of the installation are conventional. In accordance with the present invention the installation is additionally provided with a safety system.

Fitted at appropriate points in the building are detectors 22, 24 responsive to the condition of the atmosphere in the building. In the present embodiment detector 22 is responsive to smoke and detector 24 is responsive to carbon monoxide. Each is a small, self-contained commercial unit powered by an on-board battery or by a connection to the mains electrical supply, or both. While the present embodiment uses two detectors, any number of detectors from one upwards may be used in other embodiments. A single detector unit may be responsive to smoke and carbon monoxide. Detectors having other forms and/or being responsive to other atmospheric conditions (e.g. carbon dioxide concentration) may be used. It is a feature of the present embodiment that the system is able to connect to and utilise existing commercial CO and smoke detectors.

An excess of carbon monoxide may be created in the atmosphere of the building due to poor combustion taking place in the boiler 18, as a result of damage or maladjustment. If carbon monoxide concentration sensed by the detector 24 rises above a threshold level it will produce an audible alarm in a conventional manner, but - in accordance with the present invention - it will also output an emergency signal through a first signal connection 26. In the event of fire, resultant smoke in the building's atmosphere is sensed by the smoke detector 22, which will in that case produce an audible alarm and - in accordance with the present invention - will output an emergency signal to the signal connection 26.

Emergency signals from the detectors 22, 24 are transmitted through the connection 26 to a controller 28. The controller is operatively connected through a second signal connection 30 to a solenoid 32 controlling an emergency shut-off valve 34 which is formed as a solenoid valve and is incorporated in the pipe network 16, upstream of the appliances 18, 20. In the present embodiment the emergency shut-off valve 34 controls gas supply to all of the appliances 18, 20 in the building, being incorporated into the pipe network 16 immediately downstream of the gas meter 14.

During normal operation the emergency shut-off valve 34 is maintained in an open state by the controller 28. In the present embodiment it is maintained in this open state by application of a suitable voltage by the controller 28, and closes to shut off the gas supply when this voltage is removed. This is a failsafe approach - malfunctions such as interruption of the electrical supply (which might occur in a fire or other emergency) cause the supply to be shut off rather than leaving it open and unprotected.

In other embodiments a solenoid valve as such need not be used. The emergency shut-off valve may take any other suitable form. It may be replaced with another form of electrically controllable valve. By automatically shutting off the gas supply in an emergency (which may be a fire or an excess level of atmospheric CO) the system can mitigate the danger that fuel gas will contribute to a conflagration, and can avoid the danger of human poisoning by atmospheric CO due to poor fuel combustion. These are important safety benefits.

Any or all of the detectors 22, 24 and/or the controller 28 may be mains powered or maybe battery powered or may be mains powered with battery back up.

In the system depicted in Figure 1 any suitable emergency detected causes gas supply to be shut off for the entire building 10, but a suitable system may instead be zoned so that different detectors control different applicances. Figure 2 represents an alternative embodiment in which individual detectors are each associated with specific appliances, and each protected appliance (or group of appliances) is provided with a respective electrically controlled valve to shut off fuel supply.

The installation of Figure 2 is similar to that of Figure 1 in that a network 16 of gas pipes running through the building supplies mains gas received via a gas meter 14 to gas fuelled appliances which in this example comprise a boiler 18, a gas cooker 20 and also a gas fire 40. Each of the appliances is, in conventional manner, provided with a respective manually operable isolating valve 18a, 20a.

In accordance with the present invention, supply lines 18b, 20b, 40b leading respectively to each of the appliances each incorporate a respective emergency shut-off valve 18c, 20c, 40c. Associated with each of the appliances is a respective detector 18d, 20d, 40d.

Each detector is associated with its corresponding appliance in the sense that it is suitably positioned to detect atmospheric conditions in the building produced by the appliance. Typically this implies that the detector is in the same room as the appliance. The detector and its associated appliance may be in close physical proximity. Each of the detectors is connected to controller 28 in order to be capable of sending an emergency signal to it. In the present embodiment the controller 28 responds to an emergency signal from any one of the detectors 18d, 20d, 40d by closing the corresponding emergency shut-off valve 18c, 20c, 40c in order to shut off gas supply to the corresponding appliance 18, 20, 40.

In other embodiments (not illustrated) there need not be precisely one detector and one emergency shut-off valve for each appliance. For example, an alternative would be to provide a master emergency shut off valve at a point in the pipe network 16 in the path to all of the appliances (e.g. immediately downstream of the meter 14, as in the Figure 1 embodiment) to be used to provide a full shut down in the event of a fire. Other valves, each associated with one or more appliances, might be used to shut down only those appliances in the event that they produce excess carbon monoxide. The embodiments described above are used in connection with gas fuelled appliances, the gas being supplied through a mains system. But the present invention is applicable to installations in which combustible fuel is instead supplied from an on-site store, and to installations which use combustible fuel of other types. Figure 3 represents an example, in which a fuel store 50 may for example contain biomass, oil, LPG, gas or other combustible fuel which is conducted to an appliance 52 in which the fuel is burned through a supply line 53. In the present embodiment this takes the form of a boiler (water heater). The fuel store is represented simply by a box in the drawing but may take any suitable form - a pressure cylinder, tank, reservoir etc. Here, a first detector 54 is associated with the fuel store and a second detector 56 is associated with the boiler 52. Upon detection of aberrant conditions each detector is configured to send an emergency signal to controller 28, which controls emergency shut- off valve 58 incorporated in the supply line 53. In an emergency, supply of fuel to the boiler 52 is thus shut off. The functions of the controller 28 may be implemented by means of digital or analogue electronic circuitry. Figure 4 represents a simple analogue circuit used in the present embodiment of the controller 28, in relation to the single emergency shut-off valve system represented in Figure 1. The circuit is to be connected to a mains electrical supply through live and neutral connections L, N. A switching element controls supply of current to the emergency shut-off valve 34 (see Figure 1) and is in this embodiment formed as a solenoid operated supply relay 60, although it may take other forms. It is represented in Figure 4 in an "OFF" state. A user-operable start switch 62 serves to activate the system and enable fuel flow. The start switch 62 is normally open circuit but closing it momentarily completes a circuit from the live terminal L through the start switch 62 and solenoid 64 of the supply relay 60 to the neutral contact N. The resultant current flow through the solenoid 64 causes the supply relay 60 to be switched from the illustrated "OFF" state into its "ON" state, connecting the supply relay's input c to its second output b. This completes a second path for current flow through the solenoid 64, this path being from the live terminal L via a stop switch 66, a signal input relay 66, and the relay solenoid 64 itself to the neutral terminal N. Consequently when the start switch 62 is released by the user and returns to its open circuit default state, current continues to flow through the relay solenoid 64 to maintain it in the "ON" state. In this state the supply relay 60 causes the emergency shut-off valve 34 to open, as will be explained below.

The supply relay 60 remains in the "ON" state until current flow through its solenoid 64 is interrupted. In an emergency condition, this interruption is caused by the signal input relay 66, whose solenoid 68 receives the emergency signal from the detector(s) 22, 24 (see again Figure 1) which causes the signal input relay to go open circuit and the supply relay 60 to switch to its "OFF" state, closing the emergency shut-off valve 34.

The supply relay 60 can also be caused to return to its "OFF" state and so to close the emergency shut- off valve 34 because:

(a) the user operates the stop switch 66, causing it to go momentarily open circuit; or (b) electrical supply is lost. In this case the system defaults to a safe state in which the emergency shut-off valve is closed. After the system has made a transition to the "OFF" state, reactivation is carried out by operation of the start switch 62.

The circuit incorporates a supply indicator 70, formed in the present embodiment as a simple light emitter connected across the supply terminals, to show the user whether the electrical supply is being received by the controller 28. A "system active" indicator 72 is connected in parallel with the relay solenoid 64 and illuminates while the supply relay 60 is in the "ON" state.

The supply relay 60 is a double pole, double throw relay in the present embodiment. Connections to its second set of switching contacts ai, bi and ci are omitted from Figure 4 but seen in Figure 5. When the supply relay 60 is in the "ON" state as depicted, it permits AC current flow through a driver transformer 74 which steps down the mains voltage suitably to drive the emergency shut-off valve 34 to maintain it in its open state, permitting gas flow. In an emergency, supply relay 60 goes open circuit and current flow to the emergency shut-off valve 34 ceases, causing it to shut-off gas flow. It will again be observed that the system fails to a safe state, with gas flow shut-off, in the event of an interruption of electrical supply. A valve state indicator 76 connected in parallel with the emergency shut-off valve 34 is illuminated while the valve is open.

The system can provide electrical isolation in addition to shut-off of fuel flow. In the illustrated embodiment this is achieved using an electrical isolation relay 78 whose relay solenoid 80 is connected in parallel with the input side of the driver transformer 74, so that while the system is in the "ON" state current flows through it, and when the system switches to the "OFF" state this current flow ceases, changing the state of the electrical isolation relay 78. Electrical supply to the boiler 18 and the cooker 20 passes through the switching contacts of the isolation relay 78, so that when these contacts are open circuit the supply to the appliances is disconnected.

The invention makes it possible automatically to shut off fuel supply, and in certain embodiments electrical supply, to fuel burning appliances in a straightforward and automatic manner, thereby greatly reducing the risks of carbon monoxide poisoning and/or of building fires being fed by combustible fuel.

Numerous variations are possible. For example in addition or as an alternative to the smoke and CO detectors the system may incorporate detectors sensitive to natural gas, in order to shut off gas supply in the event of a gas leakage.

Claims

1. A safety system for use in relation to an installation in a building comprising an appliance fuelled with combustible material through a supply line, the safety system comprising: at least one detector responsive to conditions indicative of fire in the building, at least one electrically operable valve for incorporation into the supply line, the valve being closable to shut-off fuel flow through the supply line, and a controller configured to receive an emergency signal from the detector upon detection of a fire, and to control the electrically operable valve to close in response to the signal, thereby shutting off fuel flow through the supply line, wherein the electrically operable valve is configured to open in response to an applied electrical signal and to close in the absence of said signal, so that in the event of a loss of electrical power to the safety system fuel flow is shut off.

2. A safety system as claimed in claim 1 in which the detector is responsive to the state of the atmosphere in the building.

3. A safety system as claimed in claim 1 or claim 2 in which the detector is a smoke alarm.

4. A safety system as claimed in any preceding claim in which the detector is a self-contained, battery powered unit.

5. A safety system as claimed in any preceding claim 1 comprising at least one detector which is responsive to carbon monoxide concentration in the atmosphere of the building, the controller being configured to close the electrically operable valve in response to receipt of a signal from the said detector indicative of excess carbon monoxide in the atmosphere.

6. A safety system as claimed in any preceding claim in which the controller comprises a supply relay having a solenoid and a set of switching contact having an "OFF" state and an "ON" state, the said solenoid being connected across an electrical power supply via a signal input switching element connected to and controlled by an output signal from the detector, such that while the signal input switching element passes current and the supply relay is in the "ON" state, current passing through the solenoid maintains the supply relay in the "ON" state, and such that when the signal input switching element ceases to pass current, the current through the solenoid ceases and the supply relay switches to its "OFF" state, wherein the supply relay controls the electrically operable valve, causing it to open while the supply relay is in the "ON" state and to close when the supply relay is in the "OFF" state.

7. A safety system as claimed in claim 6 in which the supply relay comprises at least two sets of switching contacts, and wherein one of the sets of contacts serves, when closed, to conduct electrical power to the electrically operable valve to maintain it in the open state.

8. A safety system as claimed in any preceding claim for use with an installation comprising first and second appliances each fuelled with combustible material via respective first and second supply lines, the safety system comprising: first and second detectors associated respectively with the first and second appliances, and first and second electrically operable valves for incorporation into the first and second supply lines respectively, wherein the controller is configured to close the first electrically operable valve in response to an emergency signal from the first detector, and to close the second electrically operable valve in response to an emergency signal from the second detector.

9. A safety system as claimed in any preceding claim in which the controller further controls an electrical switching means through which electrical power is supplied to the appliance, and is configured to control the electrical switching means to shut off electrical power to the appliance in response to the emergency signal.