GB2246226A - Noxious fluid safety system - Google Patents

Abstract

The safety system detects and responds to a leakage of a noxious fluid, for example gaseous fuel, and comprises a detection unit 1 with a gaseous fuel detector which omits a signal when it detects a leakage, and an encoder which encodes the signal into a unique form and transmits the latter to an output of the detection unit. Operatively connected to the output is a control unit 5 including a decoder that checks and decodes a received encoded signal and then transmits to an output a signal for initiating the energisation of an electric motor coupled to a gaseous fuel flow control valve 9 in a main gaseous fuel supply line, the motor closing the valve on detection of a leakage. Resetting means allow the valve to be opened again. <IMAGE>

Description

ImProvements in or relatin to Safety Systems This invention relates to safety systems and has particular reference to safety systems for detecting and responding to leakages of noxious fluids, for example leakages of gaseous fuel in domestic premises.

Leakage of noxious fluids is always hazardous but in factories and other industrial premises may expose both buildings and operatives working. therein to serious dangers.

For example, leakage of as gaseous fuel from appliance; burning such fuel or from the pipes supplying the fuel can be extremely hazardous particularly when the leakage results in a high concentration of gaseous fuel in the premises with the consequential risk of explosion. If th premises are unoccupied for some or all of the working jay, it may some time before the leakage is noticed so giving the concentration time to build up to a dangerous level. Even if the premises are occupied, some time may elapsed before the occupier becomes aware of the leak.

After detection, there may be further delay before action is taken to turn off the supply of gaseous fuel. These delays add further to the risk of explosion.

Accordingly, it is an object of the present invention to provide a safety system that detects a leakage of noxious fluid and responds immediately thereto by terminating the supply of fluid so preventing the build-up of dangerous conditions.

According to the present invention, a safety system for detecting and responding to a leakage of a noxious fluid comprises a detection unit housing a detector responsive to the leakage and adapted to emit a warning signal on detection of leakage and an encoder for encoding the signal and transmitting it to an output, and a control unit operatively connected to the output of the detector unit to receive the encoded signal and comprising a decoder for decoding the received encoded signal and responding thereto by providing an output usable to initiate the operation of a main noxious fluid flow control means to terminate the supply of noxious fluid.

The control unit may house an electric motor which may have an output shaft adapted to be coupled to an operating handle of a flow control valve that constitutes the flow control means.

The output shaft may carry a saddle adapted to be secured to the operating handle of the flow control valve.

Preferably, the decoder checks to ensure that the received encoded signal is valid before an output is provided by the control unit.

The detection unit may incorporate means for emitting a visual and/or an audible signal on response to a leakage.

Both detection and control units may have indicators for providing a visual and/or an audible signal to indicate that the unit is powered.

The control unit may have means for providing a reset signal for causing the flow control means to allow the resumption of the supply of noxious fluid.

The invention also provides a safety installation for detecting and responding to a leakage of a noxious fluid comprising a detection unit housing a detector responsive to the leakage and adapted to emit a signal on detection of the leakage and an encoder for encoding the signal and transmitting it to an output of the unit, a control unit operatively connected to the output of the detection unit and comprising a decoder for decoding the encoded signal and responding thereto by providing an output, noxious fluid flow control means and means for actuating the flow control means on receipt of the output from the decoder to terminate the supply of noxious fluid.

The actuating means may comprise an electric motor coupled to a valve that constitutes the flow control means.

Preferably, the control unit also includes a reset control for allowing the flow control means to permit the resumption of supply of noxious fluid.

Preferably, the detector and the control units are operatively connected together by electric cables, the encoded signal being transmitted over the cables.

The electric cables may be part of the electricity supply wiring of the premises in which the system is installed.

Such an arrangement eliminates the need for additional cables between the units.

The supply wiring may, in domestic premises, be that of a 30 amp ring main for supplying electric power to electric appliances in the premises in which case both the units may be fitted with standard 13 amp plugs and can then be plugged into standard 13 amp sockets in the ring main.

By way of example only, a system embodying the invention and suitable for the detection of leakage of gaseous fuel in domestic premises will now be described in greater detail with reference to the accompanying drawing which shows the system in schematic form only.

A detection unit represented by block 1 has an electricity supply cable 2 extending from one face. The cable terminates in a standard 13 amp plug 3. In another face of the unit is an aperture 4 that permits the entry into the unit of gaseous fuel from the atmosphere. The opening is covered by gauze of some other material pervious to the fuel.

Accommodated within the unit is an encoder and a gaseous fuel detector device which is positioned close to the aperture 4. The detector device is capable of detecting and responding to the presence in the atmosphere of, for example, propane, butane and natural gas, these being the gaseous fuels most commonly used in domestic premises.

Such detector devices are known and may be of any suitable form The detector device is adapted to respond when the concentration of the gas reaches a predetermined level that is set low enough not to constitute a serious hazard.

The output of the detector device is fed to the encoder which encodes the output into a unique digital form. The output of the encoder is the transmitted over the live and neutral conductors of the cable 2.

A control unit represented by block 5 houses a decoder adapted to respond to encoded signals sent to the control unit by the detection unit. Preferably, the decoder first checks the received encoded signal to ensure that it is a valid signal. After the received signal has been checked as valid, it is decoded and the resultant output of the decoder is applied to initiate the application of power to an electric motor also housed within the control unit. The electric motor drives an output shaft 6. Attached to the end of the shaft 6 is a saddle-like component 7 that is contoured to fit over the control handle 8 of a gaseous fuel flow control valve indicated as block 9 and which is fitted to the supply main that supplies fuel to the premises. The saddle 7 may be detachably secured to the handle 8 by a quick release mechanism, if desired.

The control unit 5 also has a power supply cable 10 extending from it, the cable terminating in a standard 13 amp plug 11.

To instal the system, the detector 1 is plugged into a 13 amp socket and then placed in a convenient location in the room containing the gaseous fuel burning appliance, for example, the detector unit may be located in the kitchen of domestic premises.

The control unit 5 is secured in place with the saddle 7 seated on the handle 8 of the main gaseous fuel supply control cock or valve 9 and secured thereto, if necessary.

The plug 11 is then plugged into a socket on the same ring main as is the detector 1 or into another ring main.

Both the detector and control units may have neon indicators which light up when the respective plugs are plugged into the sockets and the power is switched on. A short duration audible signal may also be provided.

In use, the detection of gaseous fuel by the detector 1 results in a coded signal being transmitted over the ring main to the control unit 5 which responds by causing the energisation of the motor which rotates the handle 8 of the gas valve 9 to an "OFF" position so terminating the supply of gaseous fuel to the premises and stopping further leakage of fuel.

It will be appreciated that the output of the decoder may be used to actuate a relay, which may be mechanical or electronic, and which, on actuation, applies an operating voltage to the motor.

One or both of the units may also be fitted with further neon warning lights which are energised when the system responds to a leak of gaseous fuel. In addition, the detector 1 may have means for emitting an audible warning signal when the unit responds to a leak.

After the system has responded to a leak of gaseous fuel and the leak has been dealt with, both units will have to be reset, and controls for that purpose are provided.

Resetting the system energises the motor in the control unit in a direction which returns the valve to its open or "ON" position in which the supply of gaseous fuel is resumed and also terminates the generation of all warning signals.

Both units are housed in spark proof enclosures to ensure that there is no risk of leaking gaseous fuel being ignited when the units respond to a leak.

If desired, more than one detector unit may with a single control unit, the detectors being parallel connected to the common control unit. In that way, gas-fired appliances in different rooms or locations can be monitored, and leaks detected.

Although it is preferred to use the domestic electric wiring to connect the units, separate cables may be used instead. Alternatively, an ultra-sonic or radio transmission link may be used to interconnect the units the latter being adapted to operate with such transmission systems.

The flow control valve may be electro-magnetically operated, in which case the electric motor is omitted and the output of the decoder initiates energisation of the electro-magnet.

In an alternative embodiment of the invention for use with a gas supply installation fitted with a gas meter having a built-in gaseous fuel flow control cock or valve which has an external user accessible connector or handle, the output shaft 6 of the motor in the control unit is adapted to be attached to the operating handle or otherwise coupled to the user accessible connector.

The embodiments just described are particularly useful as they are readily installed in an existing gaseous fuel supply system and they do not involve any changes to the latter.

Again, in yet another embodiment of the invention, the gas meter may house both the flow control cock or valve and the drive motor. In that case, the meter housing will also have user accessible external electric terminals to which the output of the control unit is connected.

In a further embodiment of the invention, the gas meter has built in to it the control cock or valve and the control unit. In that case, the meter has an electric lead terminating in a 13-amp plug to enable the control unit to be connected with the ring main.

It will be understood the embodiments of the invention may also be installed in industrial and commercial premises, and by the use of suitable detectors, be employed for the detection of noxious fluids other than gaseous fuels.

Claims (12)

Claims.

1. A safety system for detecting and responding to a leakage of a noxious fluid comprising a detection unit housing a detector responsive to the leakage and adapted to emit an output signal on detection of the leakage and an encoder for encoding the signal and for transmitting it to an output, and a control unit adapted to be operatively connected to the output of the detection unit and comprising a decoder for decoding the received encoded signal and responding thereto by providing an output for operating a main noxious fluid flow control means to terminate the supply of noxious fluid.

2. A system as claimed in claim 1 in which the control unit houses an electric motor with an output shaft adapted to be coupled to flow control means in the form of a fluid flow control valve.

3. A system as claimed in claim 2 in which the output shaft has a saddle adapted to be secured to the operating handle of the valve.

4. A system as claimed in any one of claims 1 to 3 in which the decoder is such that it checks as valid the received encoded signal before an output is provided by the control unit.

5. A system as claimed in any one of claims 1 to 4 in which the detection unit has means for emitting a visual and/or an audible signal on response to a leakage.

6. A system as claimed in any one of claims 1 to 5 in which both detection and control units have indicators for providing a visual and/or an audible signal to indicate that the unit is powered.

7. A system as claimed in any one of claims 1 to 6 in which the control unit has means for providing a reset signal for causing the flow control means to restore the supply of noxious fluid.

8. A safety installation for detecting and responding to a leakage of a noxious fluid comprising a detection unit housing a detector responsive to the leakage and adapted to emit a signal on the detection of a leakage and an encoder for encoding the signal and transmitting it to an output of the detection unit, and a control unit operatively connected to the output of the detection unit and having a decoder for decoding a received encoded signal and responding thereto by providing an output, noxious fluid flow control means and an arrangement for actuating the fluid flow control means on receipt of the output from the decoder to terminate the supply of noxious fluid.

9. An installation as claimed in claim 8 in which the flow control means is a valve and in which the arrangement includes an electric motor.

10. An installation as claimed in claim 9 for the detection of leakages of gaseous fuels in which the motor is housed in a gas meter that meters the supply of gaseous fuel, the motor having an output shaft and means for coupling the shaft to the valve.

11. An installation as claimed in claim 9 or 10 in which the motor and the valve are housed in a gas meter that meters the supply of gaseous fuel.

12. A safety system for detecting and responding to a leakage of gaseous substantially as herein described with reference to and as illustrated by the accompanying drawing.