GB2505925A

GB2505925A - Gas detection device with removable flow restrictor

Info

Publication number: GB2505925A
Application number: GB201216481A
Authority: GB
Inventors: Steve Roberts; Patrick Roberts; Jason Condliffe
Original assignee: A 1 ENVIROSCIENCES Ltd
Current assignee: A 1 ENVIROSCIENCES Ltd
Priority date: 2012-09-14
Filing date: 2012-09-14
Publication date: 2014-03-19
Also published as: GB201216481D0

Abstract

A gas detection device comprising: a housing 2 defining an inlet aperture, the inlet aperture 27 being configured to allow a gas sample to pass therethrough; a gas sensor (8 see figure 4) located within the housing and configured to analyse at least portion of the gas sample; and a removable chamber member 5 , wherein the housing is configured to receive the removable chamber member and the removable chamber member is configured to restrict the flow of gas with respect to the gas sensor when the chamber member is received by the housing.

Description

Title: A gas detection device and method Descrirtion of Invention Embodiments of the present invention relate to gas detection devices and methods of analysing gas samples.

Many gases which are used in industrial and commercial environments can pose significant health risks to workers. In addition, such gases can also cause environmental damage if released into the atmosphere.

Gases which may cause environmental or health issues include refrigerant gases such as hydrofluorocarbons and carbon dioxide.

The detection of such gases is, therefore, important.

Gas detection devices include portable devices which are carried by a user and fixed gas detection devices which are located in areas which are at risk of exposure to such gases.

Portable gas detection devices can be used to detect gases even in locations in which there is no fixed gas detection device. However, portable gas detection devices tend to have limited capabilities and are prone to errors due to inconsistent operator use of the devices. For example, a portable gas detection device which is moved too quickly or orientated incorrectly with respect to gravity can cause movement of a gas sample with respect to a sensor of the gas detection device such that the sensor output fluctuates erroneously. These fluctuations can make it difficult to impossible to identify the location of gas leak (for example) accurately.

Fixed gas detection devices often have greater gas detection capabilities but suffer from limitations associated with their fixed location. In addition, the installation of a fixed gas detection device in each area in which the detection of such gases is important can be very expensive.

There is, therefore, a desire to provide a more capable portable gas detection device.

Aspects of embodiments of the present invention seek to ameliorate one or

more problems associated with the prior art.

Accordingly, an aspect of the present invention provides a gas detection device comprising: a housing defining an inlet aperture, the inlet aperture being configured to allow a gas sample to pass therethrough; a gas sensor located within the housing and configured to analyse at least portion of the gas sample; and a removable chamber member, wherein the housing is configured to receive the removable chamber member and the removable chamber member is configured to restrict the flow of gas with respect to the gas sensor when the chamber member is received by the housing.

The gas detection device may be portable.

The chamber member may be removable from the housing without dismantling the housing.

The chamber member may include one or more chamber baffles.

The one or more chamber baffles may at least partially define a gas sensor chamber which is configured to receive at least part of the gas sensor.

The housing may comprise a handle portion and a main body coupled to the handle portion.

The gas detection device may further comprise one or more batteries, at least part of the one or more batteries being located within the handle portion of the housing.

The gas detection device may further comprise a gas pump configured to draw gas through the inlet aperture, wherein the gas sensor is at least partially located within the handle portion.

Removal of the removable gas chamber from the housing may allow access to the gas sensor without dismantling the housing.

The removable chamber member may be configured to provide gas of the gas sample at a substantially constant pressure to the gas sensor during a sensing period, when the chamber member is received by the housing.

The removable chamber member may define a gas sample outlet which is configured to allow the gas sample to leave the confines of the housing.

The gas sample outlet may be smaller is cross-sectional size than a gas sample inlet defined, at least in part, by the chamber member.

The gas sensor may be configured to detect a hydrofluorocarbon and/or carbon dioxide.

Another aspect of the present invention provides a method of detecting a gas in a gas sample, the method comprising: providing a housing defining an inlet aperture, the inlet aperture being configured to allow a gas sample to pass therethrough; providing a gas sensor located within the housing and configured to analyse at least part of the gas sample; providing a removable chamber member; coupling the removable chamber member to the housing such that the removable chamber member is at least partially received by the housing; directing the gas sample into the removable chamber member; restricting the flow of gas with respect to the gas sensor; and analysing the gas sample using the gas sensor.

Embodiments of the present invention are described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows an external view of an embodiment; Figure 2 shows a partially exploded view of an embodiment; Figure 3 shows an external view of an embodiment; Figure 4 shows a cross-sectional view of a chamber member of an embodiment; and Figure 5 shows an external view of an embodiment.

With reference to figures 1 to 5, an embodiment of the present invention comprises a gas detection device 1. The gas detection device 1 may be a portable gas detection device. The portable gas detection device may be suitable to be carried by a single user and, in embodiments, by one hand of the user.

The gas detection device 1 comprises a housing 2 in which one or more other components of the gas detection device 1 are housed.

The housing 2 may include a handle portion 21 and a main body 22. The handle portion 21 extends from the main body 22 and is connected thereto such that a user may hold the handle portion 21 of the housing 2 to carry and manoeuvre the main body 22 of the housing 2. In embodiments, the handle portion 21 and the main body 22 are substantially rigidly connected to each other.

In embodiments, the housing 2 is formed from a first shell 23 and a second shell 24 (see figure 2). The first shell 23 and the second shell 24 couple together to form the housing 2. The first shell 23 may form a lower part of the housing 2 and the second shell 24 may form an upper part of the housing 2.

The first 23 and second 24 shells may each include a part of the handle portion 21 and a part of the main body 22 of the housing 2. The first and second shells 23,24 may be coupled together my one or more coupling arrangements. The one or more coupling arrangements may include one or more threaded members and/or one or more engagement tab members.

Accordingly, the housing 2 may define one or more apertures each configured to receive a respective threaded member. The one or more apertures may be threaded in a corresponding manner to one or more of the threaded members.

The one or more engagement tab members may each comprise a resilient hook member which may be integrally formed with one of the first and second shells 23,24 and configured to engage an abutment portion of the other of the first and second shells 23,24 to hold the two shells 23,24 together.

In embodiments, the handle portion 21 has a longitudinal axis which is inclined with respect to a main plane of the main body 22. The handle portion 21 and main body 22 may be configured with respect to each other such that, in normal operation, when the handle portion 21 is held by a user, the main body 22 is located above the user's hand and extends forward, away from the handle portion 21 (and generally away from the user).

As will be appreciated, the handle portion 21 of the housing 2 is configured to be grasped by a user's hand and may, therefore, be elongate in form.

The main body 22 of the housing 2 includes a control and display panel 3 which is located on a part of the main body 22 which is generally visible to a user during normal use. As such, the control and display panel 3 may be located in a first face 25 of the main body 22 of the housing 2. The first face may comprise an upper face of the main body 22 when the housing 2 is held by the user (with the user grasping the handle portion 21 in the normal manner).

The first face 25 opposes a second face 26 of the main body 22 of the housing 2 across a depth of the main body 22 of the housing 2 (see figure 5). As will be appreciated, in normal operation when the housing 2 is grasped by a user 2, the second face 26 will generally be adjacent at least part of the hand of the user.

In embodiments, the first face 25 is a face of the second shell 24 of the housing 2 and the second face 26 is a face of the first shell 23 of the housing 2.

The control and display panel 3 includes a user interface which may include one or more buttons 31 and one or more display elements 32. The user interface is configured to receive user input in order to control the operation of the gas detection device 1 and to display information to the user regarding the operation of the gas detection device 1.

In embodiments, the control and display panel 3 includes one or more buttons 31 which are located with respect to the handle portion 21 of the housing 2 such that they can be operated by the thumb of the hand of the user which is grasping the handle portion 21. As such, the one or more buttons 31 may be located on a part of the control and display panel 3 which is towards the handle portion 21 of the housing 2. In embodiments, the one or more buttons 31 may comprise first 31 a and second 31 b buttons.

The one or more display elements 32 may include one or more light emitting diodes. In other embodiments, the display elements 32 may include a liquid crystal display or the like.

In embodiments, the one or more display elements 32 are located remote from the handle portion 21 of the housing 2 relative to the one or more buttons 31.

The housing 2 defines an inlet aperture 27. The inlet aperture 27 is configured to receive an inlet tube 4 -as is described in more detail below. The inlet aperture 27 may be located through a part of the main body 22 of the housing 2 and may be located through an end of the main body 22 which is remote from the handle portion 21 of the housing 2.

In embodiments, the inlet aperture 27 is partly defined by the first shell 23 and partly defined by the second shell 24.

In embodiments, the housing 2 defines a chamber member receiving aperture 28. The chamber member receiving aperture 28 is configured to receive at least part of a chamber member 5. The chamber member receiving aperture 28 may be located in the second face 26 of main body 22 of the housing 2. In embodiments, the chamber member receiving aperture 28 is located in the first shell 23 of the housing 2. The chamber member receiving aperture 28 is located such that, when the housing 2 is held in the normal manner by a user, the aperture 28 is defined by a lower wall of the housing 2 which generally faces downwards.

The housing 2 may further define one or more connector apertures (no shown) which may be located in the main body 22 (e.g. in a side wall thereof) and/or the handle portion 21 of the housing 2. The one or more connector apertures are configured to receive respective one or more first connectors (not shown).

The one or more first connectors may be communicatively coupled to an external device such as a power supply or computing device or an audio output device (such as one or more audio speakers (which may be part of a pair of headphones)). One or more second connectors may be provided which are configured to cooperate with respective one or more first connectors. The one or more second connectors may be provided within the housing 2 and adjacent a respective connector aperture such that a first connector may be inserted into the connector aperture to engage a second connector. The or each second connector may be coupled to one or more components of the gas detection device 1. As such the one or more first and second connectors may be used to supply power to the gas detection device, or to attach a computing device to the gas detection device 1 for configuration purposes, or to present an output (which may be an audible output) of the gas detection device 1 to the user, for example.

The housing 2 may define one or more outwardly facing raised or textured portions which may be provided on the handle portion 21 of the housing 2 and configured to reduce the likelihood of the housing 2 slipping from a user's hand.

The housing 2 defines an internal cavity 29 which may be partly defined by the main body 22 of the housing 2 and partly defined by the handle portion 22, or may be substantially entirely defined by the main body portion 22 of the housing 2.

The internal cavity 29 is configured to receive one or more further components of the gas detection device 1.

One or more baffles and structural supports 291 may be located within the internal cavity 29. The one or more baffles and structural supports 291 may be configured to restrict the flow of gases within the internal cavity 29, and/or increase the rigidity of the housing 2, and/or support the one or more further components of the gas detection device 1.

In embodiments, the one or more baffles and structural supports 291 include a wall (or bulkhead) 292 which partially defines a gas receiving portion 6 of the internal cavity 29. The wall 292 may delineate or substantially delineate the gas receiving portion 6 of the internal cavity 29 from the remaining portion of the internal cavity 29. The wall 292 is located such that the inlet aperture 27 is adjacent the gas receiving portion 6 of the internal cavity 29.

The gas detection device 1 further includes one or more components of a gas detection circuit. In particular, the gas detection device 1 may include a circuit board 7 to which are connected one or more electrical components. The one or more electrical components may include passive components, such as capacitors and resistors, as well as active components, such as semiconductor devices.

The gas detection circuit includes a gas sensor 8 which may be mounted to the circuit board 7 or otherwise connected thereto.

The gas sensor 8 may be configured to detect the presence of one or more gases in a gas sample and to issue a corresponding sensor signal. The other components of the gas detection circuit may use the sensor signal to output in indication on the control and display panel 3 to indicate to the user the presence and/or absence of the one or more gases. The indication may be displayed to a user through the one or more display elements 32. In embodiments, the one or more display elements 32 form part of the gas detection circuit and may be mounted on the circuit board 7.

In embodiments, the one or more buttons 31 may be mounted on the circuit board 7. In embodiments, operative parts of the one or more buttons 31 are mounted on the circuit board 7 and the control and display panel 3 includes manual one or more respective manual manipulators of the one or more buttons 31. In such embodiments, depression of a manual manipulator of a button 31a,31b may cause actuation of the operative part of that button 31a,31b.

In embodiments, the gas detection circuit includes an audio output device (not shown) which is configured to output an indication to the user regarding the presence and/or absence of the one or more gases.

In embodiments, the gas detection circuit may be configured not only to provide an indication of the presence of one or more gases in a sample but also the concentration of such gases in the sample. Accordingly, the gas sensor 8 may be configured to detect the concentration of the one or more gases in the sample and to issue a corresponding sensor signal.

In embodiments, the gas detection circuit includes components to receive and store one or more user preferences regarding the operation of the gas detection device 1. The components may include the one or more buttons 31.

In embodiments, the gas detection circuit includes one or more components are provided to allow a user to set the sensitivity of the gas detection device 1.

In embodiments, the gas detection circuit includes a processor (which may be a microprocessor), and one or more memory elements. The gas detection circuit may also include one or more amplifiers, comparators and the like. The one or more memory elements may include volatile and/or non-volatile memory elements. In embodiments, the one or more memory elements are configured to store therein one or more instructions for execution by the processor. The one or more instructions may, on execution, control the operation of the gas detection device 1. The one or more instructions may, for example, change a mode of the gas detection device 1 depending on an input received by a user (e.g. through the one or more buttons). A mode change may comprise a change in the gas to be detected -for example. The one or more memory elements may also be configured to store a control or null reading against which the detection of the presence of a gas is determined or the detection of a concentration of a gas is determined. This control or null reading may be manually set by a user or may be automatically set by operation of the gas detection device 1 in an area, for example, which has normal' (e.g. ambient) levels of the gas to be detected. The one or more memory elements may also store a sensitivity value which is used to control the output of the gas detection device 1 in the event of a gas being sensed.

The sensitivity value may, for example, be set by a user. Settings from a user may be received through the one or more buttons -for example.

The gas detection circuit includes a connection to a power supply. In embodiments, the power supply comprises a battery 9 which may comprise a plurality of battery cells which may be nickel-metal hydride based cells. The battery 9 may be housed within the housing 2. In embodiments, the battery 9 is housed at least partially within the handle portion 21 of the housing 2 -preferably towards a proximal end of the handle portion 21 which is towards the main body 22 of the housing 2.

The gas detection circuit includes a gas pump 10. The gas pump 10 is connected to the inlet aperture 27 such that the gas pump 10 is configured to draw gas through the inlet aperture 27 and into the housing 2. In embodiments, a portion of the gas pump 10 is configured to be communicatively coupled to inlet tube 4 such that the inlet tube 4 is in fluid communication with the gas pump 10-in other words, the gas pump 10 may be connected to the inlet aperture 27 through a conduit (the conduit may be a tube (such as a flexible tube)). The communicative coupling (e.g. the conduit) may be housed within the housing 2. Accordingly, a first end of the inlet tube 4 and an inlet 41 may be configured for mutual engagement, and the inlet 41 and the gas pump 10 may be connected by the conduit such that gas may pass through the inlet tube 4, the inlet 41, and the conduit, to the gas pump 10.

The gas pump 10 may be located at least partially within the handle portion 21 of the housing 2. The inlet tube 4 may be held with respect to the inlet 41 of the gas pump 10 by an interference fit between the inlet tube 4 and the inlet 41. In embodiments, a portion of the inlet 41 extends through the inlet aperture 27.

A second end of the inlet tube 4 (the second end generally opposing the first end across a length of the inlet tube 4) may be configured for coupling to an adaptor 42. The adaptor 42 may be configured to be connected to an outlet of another device and/or may be configured to be held by a user such that gas may be drawn through the adaptor 42, through the inlet tube 4, through the inlet 41, into the housing 2 of the gas detection device 1 within the conduit between the inlet 41 and the gas pump 10 -the gas being drawn by operation of the gas pump 10.

The gas receiving portion 6 of the internal cavity 29 is located such that the chamber receiving aperture 28 communicatively couples a part of the gas receiving portion 6 of the internal cavity 29 with the atmosphere outside of the housing 2.

The gas sensor 8 is also located within the gas receiving portion 6 of the internal cavity 6 relative to the chamber receiving aperture 28 such that the gas sensor 8 can be accessed through the chamber receiving aperture 28.

The chamber receiving aperture 28 is, as mentioned above, configured to receive a chamber member 5.

The chamber member 5 defines a gas flow path (indicated by the arrows in figure 4). Accordingly, the chamber member 5 defines a gas sample inlet 51 which is configured to receive gas from the gas pump 10 -gas which may have been drawn through the inlet tube 4, for example. A delivery tube 52 may communicatively couple an outlet of the gas pump 10 and the gas sample inlet 51. The chamber member S may be orientated with respect to the housing 2 such that the inlet 51 is towards the gas pump 10.

The gas pump 10 is configured to draw gas through the inlet aperture 27 at a substantially constant rate and, as such, the gas pump 10 is configured to deliver gas at a substantially constant rate to the chamber member 5 (and, hence, to the gas sensor 8). A substantially constant rate' means that a substantially constant volume of gas is drawn/delivered per second. As will be apparent, this effect may only apply to a sensor period -i.e. a period during which the gas sensor 8 analyses at least a part of the gas sample.

The chamber member 5 further defines a gas sample outlet 57 (see figures 3 and 4) which is configured to allow the passage of gas therethrough out of the chamber member 5. The gas sample outlet 57 is sized to restrict the output of gas through the outlet 57 such that a backpressure is generated. In embodiments, the gas sample outlet 57 comprises a plurality of apertures. In embodiments, the gas sample outlet 57 comprises four apertures. The chamber member 5 may, in embodiments, act to stabilise the gas pressure adjacent the gas sensor 8. This may improve the reliability of the detection by the gas sensor 8 -which may, in turn, allow gas leaks to be identified and located more quickly in a manner which may be less prone to operator error.

The gas flow path is, therefore, defined by the chamber member 5 between the gas sample inlet 51 and the gas sample outlet 57.

The chamber member 5 comprises a chamber member wall 53 which at least at least partially defines a cavity 54 of the chamber member 5 (see figure 4).

The chamber member wall 53 may be a peripheral wall of the chamber member 5 and may have a generally square or rectangular external cross-sectional shape. In embodiments, the chamber member 5 further comprises a chamber member floor 55 which is coupled to the chamber member wall 53 and at least partially defines the cavity 54 of the chamber member 5.

The cavity 54 of the chamber member 5 houses one or more chamber baffles 56 which at least partially define the gas flow path between the gas sample inlet 51 and the gas sample outlet 57.

In embodiments, when the chamber member 5 is received by the chamber receiving aperture 28, the gas sensor 8 is at least partially located within the cavity 54 of the chamber member 5. The gas sensor 8 may be located within the cavity 54 in the gas flow path. With the chamber member 5 in place, the cavity 54 may be isolated from the majority of the rest of the gas receiving portion 6 of the internal cavity 29 such that little or no gas of the gas sample escapes the confines of the cavity 54 into the remainder of the gas receiving portion 6. The wall 292 serves to inhibit the passage of any gas which does escape into the gas receiving portion (as well as any fluids, dust, or the like) from passing into the rest of the internal cavity 29. This may help to prevent damage to parts of the gas detection device 1 due to exposure to the gas sample.

In embodiments, the gas sensor 8 is mounted on a circuit board 7 and the chamber member 5 is configured to abut part of the circuit board 7. In embodiments, the chamber member 5 is configured to abut part of the circuit board substantially around the gas sensor 8 so as to inhibit the flow of gas out of the cavity 54 of the chamber member 5 (other than through the gas sample outlet 57). In embodiments, the chamber member wall 53 abuts the circuit board 7 substantially entirely surrounding the gas sensor 8. In embodiments, one or more of the one or more chamber baffles 56 abuts the circuit board 7.

The one or more chamber baffles 56 are configured within the cavity 54 of the chamber member 5 with respect to the gas sensor 8 so as to maintain the flow of gas, during normal operation, along the gas flow path past the gas sensor 8 within a predetermined range of flow rates -the predetermined range of flow rates being selected to seek to ensure that the gas sensor 8 is exposed to the gas for a sufficient length of time for the gas sensor 8 to analyse the gas. In other words, the one or more chamber baffles 56 are configured to maintain a gas pressure adjacent the gas sensor 8 within a predetermined gas pressure range. In embodiments, the flow rate and, therefore, also the gas pressure are maintained at a substantially constant level adjacent the gas sensor 8. This may, in embodiments, be the case irrespective of the orientation of the housing 2 (i.e. the gas detection device 1).

In embodiments, the one or more chamber baffles 56 at least partially define a gas sensor chamber 58 within the chamber member 5. The gas sensor chamber 58 is configured to receive at least part of the gas sensor 8 when the chamber member 5 is received by the chamber receiving aperture 28. The one or more chamber baffles 56 define an inlet 581 and an outlet 582. The inlet 581 and the outlet 582 are positioned with respect to each other so as to slow the flow of gas along the gas flow path adjacent the gas sensor 8. The one or more chamber baffles 56 may extend across substantially an entire width of the cavity 54.

In the depicted embodiment, a first 561 of the one or more chamber baffles 56 defines the inlet 581 between the first chamber baffle 561 and an inner surface of the chamber member floor 55. A second 562 of the one or more chamber baffles 56 defines the outlet 582 between the second chamber baffle 562 and a surface of the circuit board 7. As such, the inlet 581 and the outlet 582 oppose each other across the gas sensor chamber 58 and across a depth of the cavity 54 of the chamber member 5 -this arrangement may, of course, be achieved with other configurations of the one or more chamber baffles 56.

In embodiments, such as the depicted embodiment, the inlet 561 is lower with respect to gravity than the outlet 562 when the housing 2 is held in the normal manner by the user.

It will be appreciated that the inlet 561 and outlet 562 may be positioned differently with respect to each other and with respect to gravity (in the normal orientation) to achieve a similar effect.

As will be understood, in accordance with embodiments of the present invention, the gas pressure in the gas sensor chamber 58 is maintained at a substantially constant gas pressure during operation of the gas detection device 1 (with a substantially constant flow rate of gas through the gas sensor chamber 58). This may be the case generally irrespective of the orientation of the housing 2 (i.e. the gas detection device 1).

The chamber member 5 is removable from the housing 2. The chamber member 5 may be held in place -received by the chamber receiving aperture 28 -by an interference fit. In embodiments, one or more resilient tags of the chamber member 5 and/or the housing 2 may help to retain the chamber member 5 in place. In embodiments, the chamber member 5 has a substantially circular external cross-sectional shape, and an external circumferential surface of the chamber member 5 (e.g. an external surface of the chamber member wall 53) may include a thread, and a corresponding thread may be provided on the housing 2 with respect to the chamber receiving aperture 28, such that the chamber member 5 can be secured with respect to the housing 2 by engagement of the respective threads. In embodiments, the chamber member 5 defines an aperture which is configured to receive a threaded member (e.g. a screw). The aperture corresponds with a threaded aperture in the housing 2 such that the threaded member may be passed through the aperture in the chamber member 5 and into the corresponding aperture in the housing 2 in order to hold the chamber member in position.

Removal of the chamber member 5 from the housing 2 allows access to the gas sensor 8. This may be useful for maintenance purposes -such as replacement of the gas sensor 8 or a part thereof.

In embodiments, one or more filters may be provided along the gas flow path.

The one or more filters may include one or more filters within the chamber member 5. The one or more filters may include one or more filters associated with the gas pump 10, the inlet tube 4, the adapter 42, the delivery tube 52, and/or the gas sample inlet 51. The one or more filters may be particulate filters configured to inhibit the exposure of the gas sensor 8 to one or more particles which could damage the gas sensor 8 or hinder its operation.

An example use of embodiments of the above described gas detection device 1 are described below by way of example.

A user may hold the gas detection device 1 by grasping the handle portion 21 of the housing 2. The use may position the inlet tube 4 such that the inlet tube 4 can draw in gas to be sampled. This may involve the attachment of the adaptor 42 to another device -a valve, an aperture, or the like. This may involve the manual manipulation of the adaptor 42 by, for example, movement of the adaptor 42 with respect to another device from which it is suspected that gas is leaking.

The user may then active the gas detection device 1 through manipulation of the control and display panel 3 -for example, by actuating one or more of the one or more buttons 31.

Activation of the gas detection device 1 causes activation of the gas pump 10 which draws a sample of gas through in through the inlet tube 4.

The gas sample is delivered by the gas pump 10 to the chamber member 5 through the gas sample inlet 51 and delivery tube 52 (if provided). In the chamber member 5, the gas sample surrounds the gas sensor 8 and passes through the gas sensor chamber 58 (from the inlet 581 to the outlet 582). The gas sensor 8 analyses at least part of the gas sample and one or more components of the gas detection circuit present one or more results of that analysis as an indication to the user through the control and display panel 3 (using the one or more display elements 32). The indication may be output to the user through an audio signal (which may be via the one or more speakers).

The gas sample then passes out of the gas detection device 1 through the gas sample outlet 57.

As will be appreciated, the output for the gas sensor 8 may be amplified and the amplified signal may be compared to a control or null reading (as mentioned above) and potentially also to a threshold value (which may be set by a user any may be stored in the one or more memory elements) to determine if a sufficient quantity of the gas is present in the sample to cause a particular indication to be presented to the user (be it an indication of the presence of a gas in the sample or the concentration of the gas in the sample).

In embodiments, there may be a plurality of thresholds associated with different gases and different concentrations of gases (the relative values of two thresholds for a particular gas may be used to determine the sensitivity of the gas detection device 1, for example).

In embodiments, the housing 2 is formed from plastic. The housing 2 may, in embodiments, be made from injection moulded plastic. The chamber member may also be formed from plastic and may be formed from injection moulded plastic.

The gas sensor 8 may be configured to sense the presence and/or concentration of one or more gases in the gas sample. In embodiments, the gas sensor 8 comprises two (or more) sub-sensors each of which is configured to sense the presence and/or concentration of a gas in the gas sample; these two (or more) gases may include hydrofluorocarbons and carbon dioxide. The or each sub-sensor may be provided in a separate package and may be independently operable with respect to the or each other sub-sensor.

The concentration of a detected gas may be indicated to the user by the illuminating of one or more display elements 32 wherein the more display elements 32 which are illuminated, the higher the detected concentration. The concentration of a detected gas may be indicated to the user by the frequency and/or amplitude of an audio signal wherein higher the frequency and/or the greater the amplitude of the audio signal, the higher the detected concentration.

When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

Claims 1. A gas detection device comprising: a housing defining an inlet aperture, the inlet aperture being configured to allow a gas sample to pass therethrough; a gas sensor located within the housing and configured to analyse at least portion of the gas sample; and a removable chamber member, wherein the housing is configured to receive the removable chamber member and the removable chamber member is configured to restrict the flow of gas with respect to the gas sensor when the chamber member is received by the housing.
2. A gas detection device according to claim 1, wherein the gas detectiondevice is portable.
3. A gas detection device according to claim 1 or 2, wherein the chamber member is removable from the housing without dismantling the housing.
4. A gas detection device according to any preceding claim, wherein the chamber member includes one or more chamber baffles.
5. A gas detection device according to claim 4, wherein the one or more chamber baffles at least partially define a gas sensor chamber which is configured to receive at least part of the gas sensor.
6. A gas detection device according to any preceding claim, wherein the housing comprises a handle portion and a main body coupled to the handle portion.
7. A gas detection device according to claim 6, further comprising one or more batteries, at least part of the one or more batteries being located within the handle portion of the housing.
8. A gas detection device according to claim 6, further comprising a gas pump configured to draw gas through the inlet aperture, wherein the gas sensor is at least partially located within the handle portion.
9. A gas detection device according to any preceding claim, wherein removal of the removable gas chamber from the housing allows access to the gas sensor without dismantling the housing.
10. A gas detection device according to any preceding claim, wherein the removable chamber member is configured to provide gas of the gas sample at a substantially constant pressure to the gas sensor during a sensing period, when the chamber member is received by the housing.
11. A gas detection device according to any preceding claim, wherein the removable chamber member defines a gas sample outlet which is configured to allow the gas sample to leave the confines of the housing.
12. A gas detection device according to claim 11, wherein the gas sample outlet is smaller is cross-sectional size than a gas sample inlet defined, at least in part, by the chamber member.
13. A gas detection device according to any preceding claim, wherein the gas sensor is configured to detect a hydrofluorocarbon and/or carbon dioxide.
14. A method of detecting a gas in a gas sample, the method comprising: providing a housing defining an inlet aperture, the inlet aperture being configured to allow a gas sample to pass therethrough; providing a gas sensor located within the housing and configured to analyse at least part of the gas sample; providing a removable chamber member; coupling the removable chamber member to the housing such that the removable chamber member is at least partially received by the housing; directing the gas sample into the removable chamber member; restricting the flow of gas with respect to the gas sensor; and analysing the gas sample using the gas sensor.
15. A gas detection device substantially as herein described with reference to the accompanying drawings.
16. A method substantially as herein described with reference to the accompanying drawings.
17. Any novel feature or novel combination of features disclosed herein.