IES20070384A2 - A gas detector - Google Patents

Abstract

A gas detector is disclosed, the gas detector having means for sensing the level of gas present in the surrounding air. The gas detector can communicate this information to a central control computer for further analysis. The gas detector also has a diagnostic module, that can monitor the status of the sensor means. The diagnostic module is also capable of communicating the status information to the central control computer, for the scheduling of appropriate maintenance operations. <Figure 1>

Description

Gas detectors are well-known devices used...to......identify--tehe— presence of various gaseous compounds in the air. They are regularly employed in industrial environments, where a variety of harmful gases can be used as components of the manufacturing processes. Any leaks of such gases need to be identified rapidly, with appropriate alarm procedures resulting from a positive detection of the gases in question.

It is known to provide a gas detector apparatus as part of a centralised building monitoring and alarm system, for example Building Management System (BMS), or large-scale distributed measurement and control systems, for example the Supervisory Control And Data Acquisition system (SCADA). Such systems allow for the monitoring of for example heating, ventilation, cooling, security, and lighting systems within a building, or the status of various pieces of equipment located about the premises. A gas detector that interfaces with such a system provides an operator at a central monitoring station with an indication as to whether harmful gases are detected or not at the location of the sensor.

However, in known prior art systems, the gas detector is operable to send a signal to the central station only when a harmful gas is detected. If no signal is received, it is generally a sign that the air is clear of harmful gases. However, it jrnay also be an indication that the sensor ' i - 1 ' component· of the ,gas detector is faulty, and unable to monitor for the presence of harmful gases. In such a case, °7 ο 3 β 4 each individual gas detector must be checked at regular intervals to ensure proper operation.

It is an object of the invention to provide a gas detector that overcomes the above problem.

Summary of the Invention Accordingly, there is provided a device for detecting a level of gas, the device comprising: a sensor module operable to detect a level of gas; a communications module in communication with the sensor module and operable to produce a first output signal, the first output signal dependent on the level of gas detected by the sensor module; and a diagnostic module operable to monitor the operational status of the sensor module, wherein the communications module is further operable to produce a second output signal to the diagnostic module, the second output signal being dependent on the current operational status of the sensor module.

The use of this device as a gas detector allows for constant monitoring of a gas level, as well as ensuring that the gas sensor used is fully operational, and not faulty.

Preferably, the communications module is operable to produce an analogue output signal and a digital output signal.

Preferably, the analogue output signal can be varied between 0 volts and 10 yolts, and between 4 milliamps and 20 milliamps. °7 0 3 β 4 It will be understood that the analogue output signal can be provided for a number of different output voltages, e.g. 0 volts to 5 volts, or 2 volts to 10 volts.

Preferably, the device further comprises audio-visual indicators, wherein the audio-visual indicators are operable to display an indication of the current level of gas detected by the sensor module.

Preferably, the communications module further comprises a voltage specificer input, wherein the output voltage of the first and second output signals is varied dependent on the input received at the voltage specifier input.

Detailed Description of the Invention An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is an overview diagram of the apparatus of the present invention; and Fig. 2 is an overview of a centralised control system utilising the apparatus of Fig. 1.

With reference to Fig. 1, a gas detector is indicated generally at 10. The gas detector 10 comprises a generally rectangular outer casing 11. The casing 11 provides protection for the contained components. The gas detector 10 further comprises a gas sensor 16 mounted within the casing 11 of the detector 10..

It will be understood that the gas sensor 16 can be chosen from the group comprising a semiconductor-based gas sensor, °?03g4 an electrochemical gas sensor, a catalytic gas sensor, an infrared gas sensor, or any other known gas sensor technology.

A plurality of apertures 13 are formed on the casing 11, to allow the gases present in the surrounding air access to the contained gas sensor 16.

The gas detector 10 further comprises a sensor monitoring component 18. The sensor monitoring component 18 is mounted within the casing ll, adjacent the gas sensor 16. The sensor monitoring component 18 is coupled to the gas sensor 16 via communication bus 20. The sensor monitoring component 18 is operable to constantly monitor the status of the gas sensor 16. The sensor monitoring component 18 is operable to record if the gas sensor 16 is fully powered. The sensor monitoring component 18 is also operable to perform basic diagnostic operations on the gas sensor 16 at regular intervals, and also to check for the presence of the sensor 16, or even the presence of a dead sensor.

The gas detector 10 further comprises an interface component 22. The interface component 22 allows for the gas detector 10 to communicate with any known controllers, or with standard monitoring and control systems, e.g. BMS, SCADA.

The gas sensor 16 is coupled with the interface component 22. The values of the current gas levels detected by the gas sensor 16 are converted by the interface component 22 into a standard output format for reading by a suitable computer or control panel.system.

The sensor monitoring component 18 is also coupled with the interface component 22.. The sensor monitoring component 18 is 0/03 34 operable to provide an indication that the gas sensor 16 in the gas detector 10 is faulty, and requires replacing. The interface component 22 is operable to convert the indication that the gas sensor 16 is faulty into a suitable analogue or digital signal for communicating via a standard communications bus .

Referring to Fig. 2, a standard control system utilising the gas detector of the present invention is indicated generally at 12. The system comprises a central control computer 14 coupled with a plurality of gas detectors 10 (it will be understood that the central computer 14 may be implemented as a control panel suitable for access). The gas detectors 10 can be located at various different locations within a building where it is desired to monitor the presence of harmful gases.

The gas detectors 10 are in communication with the central control computer 14 via communications bus 24. The gas detectors 10 are operable to indicate to the central control computer 14 the level of gases present in the vicinity of the detector 10, as measured by the contained gas sensor 16. The gas detectors 10 are also operable to indicate to the central control computer 14 the current status of the gas sensor 16 itself.

If a harmful level of gas is detected by the gas sensor 16, the gas detector 10 is capable of prompting an alarm to be indicated at the central control computer 14, from where the operator can take the necessary actions to ensure the safety of other workers.

If the gas sensor 16 is determined to be faulty or in need of replacing by the sensor monitoring component 18, the gas θ703θ4 detector 10 is capable to prompt a warning to be indicated at the central control computer 14, allowing the operator to arrange the necessary maintenance procedures.

Preferably, the interface component 22 is operable to provide analogue output signals in the ranges between 0-10 volts and 4-20 milliamps, and digital output signals of up to 1 amp at 24 volts DC, for reading by the appropriate communications bus.

It will also be understood that the interface component 22 may comprise a wireless radio-based communications module, which can communicate with a wireless station situated local to the central control computer 14. The wireless radio-based communications module may be chosen from one of an RF transceiver, a BlueTooth module, a GSM transmitter, or any known wireless communications module. Use of a wireless communications module eliminates the need for providing suitable communications bus wiring networks to accommodate the gas detector 10.

The gas detector 10 further comprises visual and audio alarm means located on the device itself. These may comprise various coloured LEDs configured to display the current status of the device, alarm buzzers, or relays that are operable to activate remote sirens, beacons, or devices to relay messages to designated operators regarding the hazardous level of gas.

The gas detector 10 further comprises a voltage specifier input (not shown). A user of the detector 10 can specify the output voltage of the output signals produced by the gas detector 10. This may be implemented as a user-operated relay or jumper system within the gas detector 10, that allows a user of the system to vary the output voltage ranges. It may also be implemented using potentiometers, or a combination of potentiometers and relays.

The invention is not limited to the embodiment described herein but can be amended or modified without departing from the scope of the present invention.

Claims (5)

1. A device for detecting a level of gas, the device comprising: a sensor module operable to detect a level of gas; a communications module operable to produce a first output signal, the first output signal dependent on the level of gas detected by the sensor module; and a diagnostic module operable to monitor the operational status of the sensor module, wherein the communications module is further operable to produce a second output signal, the second output signal dependent on the current operational status of the sensor module.

2. The device of claim 1, wherein the communications module is operable to produce an analogue output signal and a digital output signal.

3. The device of claim 2, wherein the analogue output signal can be varied between 0 volts and 10 volts, and between 4 milliamps and 20 milliamps.

4. The device of claim 1, wherein the device further comprises audio-visual indicators, wherein the audio-visual indicators are operable to display an indication of the current level of gas detected by the sensor module.

5. A device for detecting a level of gas substantially as described herein, with reference to Fig. 1 of the drawings.