WO2015071691A1

WO2015071691A1 - Gas monitoring apparatus with remote controller

Info

Publication number: WO2015071691A1
Application number: PCT/GB2014/053394
Authority: WO
Inventors: Derek Gennard
Original assignee: S3 Id Limited
Priority date: 2013-11-15
Filing date: 2014-11-17
Publication date: 2015-05-21
Also published as: GB2525141A; GB201320241D0

Abstract

Gas monitoring apparatus (10) includes a gas monitor (12), which in use is carried by a user, for generating a gas monitor signal (14) including gas concentration data (32) indicating a gas level at a location of the user. The apparatus (10) includes an identifier (16), which in use is carried by the user, which provides an identity signal (18) including an identification code (38) indicating the identity of the user. The apparatus (10) includes a plurality of locators (20) for providing a location signal (22) including a location code (42) indicating the location of the user. The apparatus (10) includes one or more transmitters (24) for transmitting the gas concentration data (32), the identification code (38) and the location code (42) to a controller (26).

Description

GAS MONITORING APPARATUS WITH REMOTE CONTROLLER

The present invention relates to gas monitoring apparatus. Conventionally, gas monitoring apparatus for monitoring local gas concentrations is fixed in position in locations where there is a risk of a hazardous gas concentration occurring. In other arrangements, one or some or all persons at risk in hazardous environments can carry gas monitoring apparatus. However, there are numerous disadvantages with these arrangements. The gas monitoring apparatus must be checked regularly by the person carrying the apparatus or in the vicinity of the apparatus. Should there be a hazardous incident, the number and locations of local personnel may not be known in relation to the incident. According to a first aspect of the present invention, there is provided gas monitoring apparatus, the apparatus including a gas monitor which in use is carried by a user for generating a gas monitor signal including gas concentration data indicating a gas level at a location of the user, an identifier which in use is carried by the user which provides an identity signal including an identification code indicating the identity of the user, and a locator for providing a location signal including a location code indicating the location of the user, the apparatus including one or more transmitters for transmitting the gas concentration data, the identification code and the location code to a controller.

Possibly, the controller receives signals from both the gas monitor and the identifier.

Possibly, the identifier includes an identifier transmitter for transmitting the identity signal.

Possibly, the apparatus includes a plurality of locators. Possibly, the or each locator includes an identity signal receiver, which may receive the identity signal transmitted by the identifier when the user carrying the identifier comes within a predefined range of the receiver.

Possibly, the or each locator is located in a known location and the location code is uniquely allocated to the location. Possibly, the location signal includes the identification code and the location code.

Possibly, the apparatus is arranged so that when the user carrying the identifier comes within the predefined range of the receiver of the or one of the locators, the locator transmits the location signals to the controller.

Possibly, the controller includes a plurality of location data records, each of which includes a location time data item, an identity data item and a location data item.

Possibly, the location time data item relates to the time at which the location signal is received by the controller. Possibly, the identity data item relates to the identification code, and may, for example, comprise the name of the user which could be generated from the identification code and a relation table which relates the identification codes to user data such as names, employee numbers etc.

Possibly, the location data item relates to or comprises the location code, which is unique to the location of the identity signal receiver, and may, for example, comprise the name of the location generated from the location code and a relation table which relates location codes to location names.

Possibly, the gas monitor includes a detector for detecting atmospheric gas concentrations in the vicinity of the user, which provides the gas concentration data. Possibly, the gas monitor is allocated a unique allocation code. Possibly, the gas monitor signal includes the gas concentration data and the allocation code. Possibly, the gas monitor includes a gas monitor transmitter for transmitting the gas monitor signals. Possibly, the apparatus includes a gas monitor signal receiver which receives the gas monitor signals and relays them to the controller. Possibly, the controller includes a plurality of gas monitor data records, each of which may include a gas monitor time data item, an allocation data item and a gas concentration data item.

Possibly, the gas monitor time data item relates to the time at which the gas concentration data is received by the controller. Possibly, the allocation data item relates to the allocation code, and may, for example, comprise the name of the user generated from the allocation code and a relation table which relates the allocation codes to user data such as names, employee numbers etc. Possibly, the allocation data item comprises the corresponding identity data item. Possibly, the gas concentration data item relates to or comprises the gas concentration data.

Possibly, the controller includes a plurality of gas concentration and location data records, which may include a plurality of data items collated from corresponding location data records and gas monitor data records, which may correspond in time (within a predetermined tolerance) and identity of the user. Each gas concentration and location data record may include one of the gas monitor time data items (or the corresponding one of the location time data items), one of the identity data items (or a corresponding one of the allocation data items), a corresponding one of the location data items and a corresponding one of the gas concentration items.

Possibly, the apparatus includes an output, which may comprise a display screen, for displaying user selected data items from the controller. Possibly, in use, the user carries both the gas monitor and the identifier. Possibly, in use the gas monitor continuously transmits the gas monitor signals to the controller as the user moves around. Possibly, in use, as the user moves within range of one locator, the identifier transmits the identity signals to the one locator and from thence the location signals are transmitted to the controller.

Possibly, the controller collates the location data items and the identity data items to the gas concentration data items at corresponding similar time data items for the same user.

Possibly, the apparatus includes a plurality of gas monitors and identifiers, for a plurality of users.

Possibly, the apparatus includes predefined gas concentration alarm levels which trigger audible or visual alarm messages. Possibly, the apparatus includes one or more transmitters for transmitting the alarm messages from the controller to the user. Possibly, the transmitter(s) and the receiver(s) comprise transceiver(s) and may relay alarm messages to the gas monitor and/or the identifier. Possibly, the gas monitor and/or the identifier include an alarm device, which may include a visual indicator (such as an indicator light) and/or an audible indicator (such as a speaker). Possibly, the gas monitor transmitter and the gas monitor receiver comprise a wireless transmission system such as a Wi-Fi system, which may extend over a predetermined area, such as a plant. The Wi-Fi may operate at a frequency of 2.4 or 5 GHz. Possibly, the identifier transmitter and the identity signal receiver comprise an ultra wide band (UWB) wireless communication system.

Possibly, the gas monitor transmitter, the gas monitor receiver, the identifier transmitter and the identity signal receiver comprise a wireless transmission system such as a Wi-Fi system, which could extend over a predetermined area, such as a plant. The Wi-Fi may operate at a frequency of 2.4 or 5 GHz. Possibly, the gas monitor transmitter, the gas monitor receiver, the identifier transmitter and the identity signal receiver comprise a radio frequency (RF) system. Possibly, the identifier transmitter and the identity signal receiver comprise a relative short range wireless system.

Possibly, the identifier transmitter and the identity signal receiver each comprise a transceiver. Possibly, the identity signal transceiver transmits an enquiry signal to the identifier which, when within a predetermined range, prompts the identifier to transmit the identity signal. The predetermined range may be no more than 2 metres.

Possibly, the gas monitor is arranged to monitor one or a plurality of gas concentrations, which may be toxic and/or explosive. Possibly, the gas monitor monitors the concentration of any one or suitable combination of oxygen, carbon monoxide, hydrogen sulphide, sulphur dioxide, carbon dioxide, ozone, chlorine, or ammonia. Possibly, the gas monitor monitors the concentration of vapour.

Possibly, the apparatus comprises a gas monitor/location device, which includes both the gas monitor and the identifier, and may be in the form of a tag. Possibly, the device combines the features and functions of both the gas monitor and the identifier as previously described, with the advantage that the user has to carry only one item. Advantageously, the gas monitor still essentially operates separately to the identifier and vice versa.

Possibly, the gas monitor and the identifier are integrated in the device. Possibly, the device comprises the identification code and the gas detector which provides the gas concentration data. Possibly, the identification code comprises the allocation code.

Possibly, the device includes a transmitter for transmitting a combined identity/gas monitor signal to the locator. Possibly, the combined identity/gas monitor signal comprises the identity signal and the gas monitor signal. Possibly, the locator transmits a combined identity/location/gas monitor signal to the controller. Possibly, the combined identity/location/gas monitor signal comprises the identification code, the location code and the gas concentration data.

Possibly, the gas concentration data is transmitted via the locator(s) to the controller.

Possibly, the locator transmits a location signal to the device. Possibly, the device includes a location code, which may be provided by or derived from the location signal.

Possibly, the device includes a transmitter for transmitting a combined identity/location/gas monitor signal to the gas monitor receiver and thence to the controller. Possibly, the combined identity/location/gas monitor signal comprises the identification code, the location code and the gas concentration data.

Possibly, the location code is transmitted via the gas monitor receiver to the controller.

Possibly, the locator comprises a satellite location system such as

GPS. According to a second aspect of the present invention, there is provided a method of monitoring gas concentrations, the method including providing gas monitoring apparatus, the apparatus including a gas monitor which in use is carried by a user for generating a gas monitor signal including gas concentration data indicating a gas level at a location of the user, an identifier which in use is carried by the user which provides an identity signal including an identification code indicating the identity of the user, and a locator for providing a location signal including a location code indicating the location of the user, the apparatus including one or more transmitters for transmitting the gas concentration data, the identification code and the location code to a controller.

Possibly, the apparatus includes any of the features described in any of the preceding statements or following description. Possibly, the method includes any of the steps described in any of the preceding statements or following description.

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

Fig. 1 is a schematic view of gas monitoring apparatus, with Fig. 1A being an enlarged detail view of a gas monitor and Fig. 1 B being an enlarged detail view of an identifier;

Fig. 2 is a schematic view of another gas monitoring apparatus;

Fig. 3 is a schematic view of yet another gas monitoring apparatus; and Fig. 4 is a schematic view of still yet another gas monitoring apparatus.

Fig. 1 shows gas monitoring apparatus 10, the apparatus 10 including a gas monitor 12, which in use is carried by a user, for generating a gas monitor signal 14 including gas concentration data 32 indicating a gas level at a location of the user. The apparatus 10 includes an identifier 16, which in use is carried by the user, which provides an identity signal 18 including an identification code 38 indicating the identity of the user. The apparatus 10 includes a plurality of locators 20 for providing a location signal 22 including a location code 42 indicating the location of the user. The apparatus 10 includes one or more transmitters 24 for transmitting the gas concentration data 32, the identification code 38 and the location code 42 to a controller 26. In the embodiment shown in Fig. 1 , the identifier 16 is in the form of a radio frequency (RF) location tag 28. The tag 28 includes the unique identification code 38. The tag 28 includes an identifier transmitter 24B for transmitting the identity signals 18. The radio frequency location tag 28 could be an RFID tag.

Each locator 20 includes an identity signal receiver 40 which receives the identity signals 18 transmitted by the tag 28 when the user carrying the tag 28 comes within a predefined range of the receiver 40. In use, each locator 20 is located in a known location and the location code 42 is uniquely allocated to the location. The location signal 22 includes the identification code 38 and the location code 42.

As shown in Fig. 1 , when the user carrying the tag 28 comes within the predefined range of the receiver 40 of one of the locators 20, for example as shown, the locator 20A, the locator 20A transmits the location signals 22, in this example as shown, by cabling 44, to a location controller 46. It will be realised that wireless transmission means or other suitable transmission means could also be utilised instead of the cabling 44.

The location controller 46 includes a plurality of location data records 50, each of which includes a location time data item 52, an identity data item 54 and a location data item 56.

The location time data item 52 relates to the time at which the location signal 22 is received by the location controller 46. The identity data item 54 relates to the identification code 38, and could, for example, comprise the name of the user generated from the identification code 38 and a relation table (not shown) which relates identification codes 38 to user data such as names, employee numbers etc. The location data item 56 relates to or comprises the location code 42, which is unique to the location of the identity signal receiver 40, and could, for example, comprise the name of the location generated from the location code 42 and a relation table (not shown) which relates location codes to location names . The gas monitor 12 could be in the form of a tag 29 and includes a detector 30 for detecting atmospheric gas concentrations in the vicinity of the user, which provides the gas concentration data 32. The gas monitor 12 is allocated a unique allocation code 34. The gas monitor signal 14 includes the gas concentration data 32 and the allocation code 34. The gas monitor 12 includes a gas monitor transmitter 24A for transmitting the gas monitor signals 14.

The apparatus 10 includes a gas monitor signal receiver 36 which receives the gas monitor signals 14 and relays them to a gas monitor controller 58. The gas monitor controller 58 includes a plurality of gas monitor data records 60, each of which includes a gas monitor time data item 62, an allocation data item 64 and a gas concentration data item 66. The gas monitor time data item 62 relates to the time at which the gas concentration data 32 is received by the gas monitor controller 58. The allocation data item 64 relates to the allocation code 34, and could, for example, comprise the name of the user generated from the allocation code 34 and a relation table (not shown) which relates allocation codes 34 to user data such as names, employee numbers etc. In one example, the allocation data item 64 could comprise the corresponding identity data item 54. The gas concentration data item 66 relates to or comprises the gas concentration data 32.

The apparatus 10 includes a gas concentration and location controller 68 which includes a plurality of gas concentration and location data records 70, which include data items collated from corresponding location data records 50 and gas monitor data records 60, which correspond in time (within a predetermined tolerance) and identity of the user. Each gas concentration and location data record 70 includes one of the gas monitor time data items 62 (or the corresponding one of the location time data items 52), one of the identity data items 54 (or a corresponding one of the allocation data items 64), a corresponding one of the location data items 56 and a corresponding one of the gas concentration items 66. The location controller 46, the gas monitor controller 58 and the gas concentration and location controller 68 together comprise the controller 26.

The apparatus 10 includes an output 74 which could comprise a display screen for displaying user selected data items from the gas concentration and location controller 68.

In use, the user is fitted with both the gas monitor 12 and the identifier 16. In one example, the gas monitor 12 continuously transmits gas monitor signals 14 as the user moves around, building up a sequence of gas monitor data records 60 at the gas monitor controller 58. As the user moves within range of one locator 20A of the locators 20, the identity signals 18 are transmitted from the identifier 16 to the locator 20A and from thence the location signals 22 are transmitted to the location controller 46.

The gas concentration and location controller 68 collates the location data items 56 and the identity data items 54 to the gas concentration data items 66 at corresponding similar time data items 52, 62 for the same user. As the user moves around, the apparatus builds up records 50, 60, 70 showing gas concentrations at different locations. The apparatus 10 could include a plurality of gas monitors 12 and identifiers 16, for a plurality of users.

The output 74 could, for example, include a map showing recorded gas concentrations at different locations, generated as the users move around. In another example, the output 74 could include gas concentrations experienced by a particular user over a period of time.

There are a number of advantages to this apparatus. Gas concentrations are automatically measured most at locations which users frequent most. Wherever users move, the gas concentration is automatically monitored, even if the location is relatively remote or unpopulated. The exposure history of each user can be automatically centrally recorded for health and safety reasons. The cumulative exposure of a user can be monitored and alarms raised if alarm levels are exceeded. If a problem arises, the last known locations of the users are centrally logged to enable rapid and accurate emergency response to the correct location.

The apparatus 10 could include predefined gas concentration alarm levels which trigger audible or visual alarm messages. The apparatus 10 could include one or more transmitters (not shown) for transmitting the alarm messages from the controller 26 to the users. In one example, the transmitters 25 and the receivers 36, 40 comprise transceivers and could relay alarm messages to the gas monitor 12 and/or the identifier 16, each of which could include an alarm device 76 which could include a visual indicator (such as an indicator light) and/or an audible indicator (such as a speaker). In one example, the gas monitor transmitter 24A and the gas monitor receiver 36 comprise a wireless transmission system such as a Wi-Fi system, which could extend over a predetermined area, such as a plant. In one example, the Wi-Fi could have a frequency of 2.4 or 5 GHz The identifier transmitter 24B and the identity signal receiver 40 could comprise an ultra wide band (UWB) wireless communication system.

In another example, the gas monitor transmitter 24A, the gas monitor receiver 36, the identifier transmitter 24B and the identity signal receiver 40 comprise a wireless transmission system such as a Wi-Fi system, which could extend over a predetermined area, such as a plant. The Wi-Fi could have a frequency of 2.4 or 5 GHz.

In yet another example, the gas monitor transmitter 24A, the gas monitor receiver 36, the identifier transmitter 24B and the identity signal receiver 40 comprise a radio frequency (RF) system. The identifier transmitter 24B and the identity signal receiver 40 could comprise a relative short range wireless system. In another example, the identifier transmitter 24B and the identity signal receiver 40 could each comprise a transceiver. The identity signal transceiver 40 could transmit an enquiry signal (not shown) to the identifier 16 which, when within a predetermined range, prompts the identifier 16 to transmit the identity signal 18. The predetermined range could be no more than 2 metres.

The gas monitor 12 could be arranged to monitor one or a plurality of gas concentrations, which could be toxic and/or explosive. For example, the gas monitor 12 could monitor the concentration of any one or suitable combination of oxygen, carbon monoxide, hydrogen sulphide, sulphur dioxide, carbon dioxide, ozone, chlorine, or ammonia. The gas monitor 12 could monitor the concentration of vapour. Figs 2 to 4 show other embodiments of the invention, many features of which are similar to those already described in relation to the embodiment of Fig. 1 . Therefore, for the sake of brevity, the following embodiments will only be described in so far as they differ from the embodiment already described. Where features are the same or similar, the same reference numerals have been used and the features will not be described again.

Fig. 2 shows another gas monitoring apparatus 1 10, which comprises a gas monitor/location device 84 which includes both the gas monitor 12 and the identifier 16, and could be in the form of a tag. The tag 184 combines the features and functions of both the gas monitor 12 and the identifier 16 as previously described, with the advantage that the user has to carry only one item. Advantageously, the gas monitor 12 still essentially operates separately to the identifier 16 and vice versa. Fig. 3 shows yet another gas monitoring apparatus 210, which comprises a gas monitor/location device 284 which again includes both the gas monitor 12 and the identifier 16, and could be in the form of a tag. In this embodiment, the gas monitor 12 and the identifier 16 are integrated, giving a more efficient system, but without the redundancy of previous systems.

The gas monitor/location device 284 includes an identification code 38, and a gas detector 30 which provides the gas concentration data 32. In this embodiment, the unique allocation code 34 comprises the identification code 38.

The device 284 includes a transmitter 24C for transmitting a combined identity/gas monitor signal 78 to the locator 20, the combined identity/gas monitor signal 78 comprising the identity signal 18 and the gas monitor signal 14. The locator 20 transmits a combined identity/location/gas monitor signal 80 to the gas concentration and location controller 68, the combined identity/location/gas monitor signal 80 comprising the identification code 38, the location code 42 and the gas concentration data 32.

In this embodiment, the gas concentration data 32 is thus transmitted via the locators 20 to the controller 26. Fig. 4 shows still another gas monitoring apparatus 310, which comprises a gas monitor/location device 384 which again includes both the gas monitor 12 and the identifier 16, and could be in the form of a tag.

In this embodiment, the locator 20 transmits a location signal 22 to the device 384. The device 384 includes an identification code 38, a gas detector 30 which provides the gas concentration data 32 and a location code 42, which in this embodiment, is provided by or derived from the location signal 22. The device 384 includes a transmitter 24C for transmitting a combined identity/location/gas monitor signal 80 to the gas monitor receiver 36 and thence to the gas concentration and location controller 68, the combined identity/location/gas monitor signal 80 comprising the identification code 38, the location code 42 and the gas concentration data 32.

In this embodiment, the location code 42 is thus transmitted via the gas monitor receiver 36 to the controller 26.

In this embodiment, the locators 20 could comprise satellite location systems such as GPS. Advantageously, the gas monitor apparatus of the invention can utilise existing infrastructure such as existing gas monitoring systems and personnel location/tracking systems.

Various other modifications could be made without departing from the scope of the invention. The apparatus and the various components thereof could be of any suitable size and shape, and could be formed of any suitable material.

Any of the features or steps of any of the embodiments shown or described could be combined in any suitable way, within the scope of the overall disclosure of this document.

There is thus provided gas monitor apparatus which provides gas concentration data, location and identity information to a central controller. The concentrations of gases are automatically most intensively monitored where the personnel density is greatest, and the gas concentration is measured in the vicinity of every user. An exposure history can be built up for each user. In case of a hazardous incident, the location of each user is known, allowing precise and rapid routing of emergency response teams to the users affected.

Claims

1 . Gas monitoring apparatus, the apparatus including a gas monitor which in use is carried by a user for generating a gas monitor signal including gas concentration data indicating a gas level at a location of the user, an identifier which in use is carried by the user which provides an identity signal including an identification code indicating the identity of the user, and a locator for providing a location signal including a location code indicating the location of the user, the apparatus including one or more transmitters for transmitting the gas concentration data, the identification code and the location code to a controller.

2. An apparatus according to claim 1 , in which the controller receives signals from both the gas monitor and the identifier.

3. An apparatus according to claims 1 or 2, in which the identifier includes an identifier transmitter for transmitting the identity signal.

4. An apparatus according to any of claims 1 to 3, in which the apparatus includes a plurality of locators.

5. An apparatus according to any of the preceding claims, in which the or each locator includes an identity signal receiver, which receives the identity signal transmitted by the identifier when the user carrying the identifier comes within a predefined range of the receiver.

6. An apparatus according to any of the preceding claims, in which the or each locator is located in a known location and the location code is uniquely allocated to the location.

7. An apparatus according to any of the preceding claims, in which the location signal includes the identification code and the location code.

8. An apparatus according to claim 5 or any claim dependent thereon, in which the apparatus is arranged so that when the user carrying the identifier comes within the predefined range of the receiver of the or one of the locators, the locator transmits the location signals to the controller.

9. An apparatus according to any of the preceding claims, in which the controller includes a plurality of location data records, each of which includes a location time data item, an identity data item and a location data item.

10. An apparatus according to claim 9, in which the location time data item relates to the time at which the location signal is received by the controller.

1 1 . An apparatus according to claims 9 or 10, in which the identity data item relates to the identification code.

12. An apparatus according to claim 1 1 , in which the identity data item comprises the name of the user, which may be generated from the identification code and a relation table which relates the identification codes to user data such as names, employee numbers etc.

13. An apparatus according to any of claims 9 to 12 when dependent on claim claim 5 or any claim dependent thereon, in which the location data item relates to or comprises the location code, which is unique to the location of the identity signal receiver.

14. An apparatus according to claim 13, in which the location data item comprises the name of the location generated from the location code and a relation table which relates location codes to location names.

15. An apparatus according to any of the preceding claims, in which the gas monitor includes a detector for detecting atmospheric gas concentrations in the vicinity of the user, which provides the gas concentration data.

16. An apparatus according to any of the preceding claims, in which the gas monitor is allocated a unique allocation code and the gas monitor signal includes the gas concentration data and the allocation code.

17. An apparatus according to any of the preceding claims, in which the gas monitor includes a gas monitor transmitter for transmitting the gas monitor signals.

18. An apparatus according to any of the preceding claims, in which the apparatus includes a gas monitor signal receiver which receives the gas monitor signals and relays them to the controller.

19. An apparatus according to any of the preceding claims, in which the controller includes a plurality of gas monitor data records, each of which includes a gas monitor time data item, an allocation data item and a gas concentration data item.

20. An apparatus according to claim 19, in which the gas monitor time data item relates to the time at which the gas concentration data is received by the controller.

21 . An apparatus according to claims 19 or 20, in which the allocation data item relates to the allocation code.

22. An apparatus according to claim 21 , in which the allocation data item comprises the name of the user, which may be generated from the allocation code and a relation table which relates the allocation codes to user data such as names, employee numbers etc.

23. An apparatus according to any of claims 19 to 22 when dependent on claim 9 or any claim dependent thereon, in which the allocation data item comprises the corresponding identity data item.

24. An apparatus according to any of claims 19 to 23, in which the gas concentration data item relates to or comprises the gas concentration data.

25. An apparatus according to claim 19 or any claim dependent thereon, when dependent on claim 9 or any claim dependent thereon, in which the controller includes a plurality of gas concentration and location data records, which include a plurality of data items collated from corresponding location data records and gas monitor data records, which correspond in time (within a predetermined tolerance) and identity of the user.

26. An apparatus according to claim 25, in which each gas concentration and location data record includes one of the gas monitor time data items (or the corresponding one of the location time data items), one of the identity data items (or a corresponding one of the allocation data items), a corresponding one of the location data items and a corresponding one of the gas concentration items.

27. An apparatus according to any of the preceding claims, in which the apparatus includes an output, which may comprise a display screen, for displaying user selected data items from the controller.

28. An apparatus according to any of the preceding claims, in which, in use, the user carries both the gas monitor and the identifier.

29. An apparatus according to any of the preceding claims, in which, in use, the gas monitor continuously transmits the gas monitor signals to the controller as the user moves around.

30. An apparatus according to any of the preceding claims, in which, in use, as the user moves within range of one locator, the identifier transmits the identity signals to the one locator and from thence the location signals are transmitted to the controller.

31 . An apparatus according to claim 19 or any claim dependent thereon, when dependent on claim 9 or any claim dependent thereon, in which the controller collates the location data items and the identity data items to the gas concentration data items at corresponding similar time data items for the same user.

32. An apparatus according to any of the preceding claims, in which the apparatus includes a plurality of gas monitors and identifiers, for a plurality of users.

33. An apparatus according to any of the preceding claims, in which the apparatus includes predefined gas concentration alarm levels which trigger audible or visual alarm messages.

34. An apparatus according to claim 33, in which the apparatus includes one or more transmitters for transmitting the alarm messages from the controller to the user.

35. An apparatus according to claim 34, in which the transmitter(s) and the receiver(s) comprise transceiver(s) and relay alarm messages to the gas monitor and/or the identifier.

36. An apparatus according to any of the preceding claims, in which the gas monitor and/or the identifier include an alarm device, which may include a visual indicator (such as an indicator light) and/or an audible indicator (such as a speaker).

37. An apparatus according to claim 18 or any claim dependent thereon, in which the gas monitor transmitter and the gas monitor receiver comprise a wireless transmission system such as a Wi-Fi system, which extends over a predetermined area, such as a plant and may operate at a frequency of 2.4 or 5 GHz.

38. An apparatus according to claim 5 or any claim dependent thereon, in which the identifier transmitter and the identity signal receiver comprise an ultra wide band (UWB) wireless communication system.

39. An apparatus according to claim 18 or any claim dependent thereon, when dependent on claim 5 or any claim dependent thereon, in which the gas monitor transmitter, the gas monitor receiver, the identifier transmitter and the identity signal receiver comprise a wireless transmission system such as a Wi-Fi system, which could extend over a predetermined area, such as a plant and may operate at a frequency of 2.4 or 5 GHz.

40. An apparatus according to claim 19 when dependent on claim 5 or any claim dependent thereon, in which the gas monitor transmitter, the gas monitor receiver, the identifier transmitter and the identity signal receiver comprise a radio frequency (RF) system.

41 . An apparatus according to claim 5 or any claim dependent thereon, in which the identifier transmitter and the identity signal receiver comprise a relative short range wireless system.

42. An apparatus according to claim 5 or any claim dependent thereon, in which the identifier transmitter and the identity signal receiver each comprise a transceiver.

43. An apparatus according to claim 42, in which the identity signal transceiver transmits an enquiry signal to the identifier which, when within a predetermined range, prompts the identifier to transmit the identity signal.

44. An apparatus according to claim 43, in which the predetermined range is no more than 2 metres.

45. An apparatus according to any of the preceding claims, in which the gas monitor is arranged to monitor one or a plurality of gas concentrations, which are toxic and/or explosive.

46. An apparatus according to claim 45, in which the gas monitor monitors the concentration of any one or suitable combination of oxygen, carbon monoxide, hydrogen sulphide, sulphur dioxide, carbon dioxide, ozone, chlorine, or ammonia.

47. An apparatus according to any of the preceding claims, in which the gas monitor monitors the concentration of vapour.

48. An apparatus according to any of the preceding claims, in which the apparatus comprises a gas monitor/location device, which includes both the gas monitor and the identifier, and may be in the form of a tag.

49. An apparatus according to claim 48, in which the device combines the features and functions of both the gas monitor and the identifier as defined in any of claims 1 to 47.

50. An apparatus according to claims 48 or 49, in which the gas monitor still essentially operates separately to the identifier and vice versa.

51 . An apparatus according to any of claims 48 to 50, in which the gas monitor and the identifier are integrated in the device.

52. An apparatus according to any of claims 48 to 51 , in which the device comprises the identification code and the gas detector which provides the gas concentration data.

53. An apparatus according to claim 52 when dependent on claim 16 or any claim dependent thereon, in which the identification code comprises the allocation code.

54. An apparatus according to any of claims 48 to 53, in which the device includes a transmitter for transmitting a combined identity/gas monitor signal to the locator.

55. An apparatus according to claim 54, in which the combined identity/gas monitor signal comprises the identity signal and the gas monitor signal.

56. An apparatus according to any of the preceding claims, in which the locator transmits a combined identity/location/gas monitor signal to the controller.

57. An apparatus according to claim 56, in which the combined identity/location/gas monitor signal comprises the identification code, the location code and the gas concentration data.

58. An apparatus according to any of the preceding claims, in which the gas concentration data is transmitted via the locator(s) to the controller.

59. An apparatus according to claim 48 or any claim dependent thereon, in which the locator transmits a location signal to the device.

60. An apparatus according to claim 59, in which the device includes a location code, which is provided by or derived from the location signal.

61 . An apparatus according to claims 59 or 60, in which the device includes a transmitter for transmitting a combined identity/location/gas monitor signal to the gas monitor receiver and thence to the controller.

62. An apparatus according to claim 61 , in which the combined identity/location/gas monitor signal comprises the identification code, the location code and the gas concentration data.

63. An apparatus according to claim 18 or any claim dependent thereon, in which the location code is transmitted via the gas monitor receiver to the controller.

64. An apparatus according to any of the preceding claims, in which the locator comprises a satellite location system such as GPS.

65. A method of monitoring gas concentration, the method including providing gas monitoring apparatus, the apparatus including a gas monitor which in use is carried by a user for generating a gas monitor signal including gas concentration data indicating a gas level at a location of the user, an identifier which in use is carried by the user which provides an identity signal including an identification code indicating the identity of the user, and a locator for providing a location signal including a location code indicating the location of the user, the apparatus including one or more transmitters for transmitting the gas concentration data, the identification code and the location code to a controller.

66. A method according to claim 65, in which the apparatus includes any of the features defined in any of claims 1 to 64.

67. Gas monitoring apparatus substantially as hereinbefore described and/or with reference to any of the accompanying drawings.

68. A method of monitoring gas concentrations substantially as hereinbefore described and/or with reference to any of the accompanying drawings.