Gas sampling in utility enclosures

Abstract

A gas sampling device 10 for utility infrastructure enclosures comprises a housing 12 defining a chamber 14, and a gas sensor 24 arranged to detect a property of gas within the chamber 14. The housing

Description

Technical Field The present disclosure relates to device for sampling gas, particularly, but not exclusively, to a device for sampling gas in utility enclosures. Background All utility infrastructure assets degrade over time. In the electrical transmission and distribution industry, failure of underground cabling or other associated equipment may ultimately lead to serious (and potentially fatal) events concerning failure of enclosures, such as manhole covers. Pressure build-up due to chemical reactions can lead to fires if flammable gases are ignited by an electrical arc. This can be potentially followed by an explosion that displaces or launches the manhole cover into the air with devastating consequences to public safety and damage to vehicles and buildings. A wide range of evolved flammable toxic gases may develop in manholes due to intensive thermal decomposition of polymeric material as a result of combustion or pyrolysis. Decomposition of polymers causes the most severe outcomes when the rapid combustion of gases leads to increased pressure and temperature within the manhole, potentially displacing covers. Ignition of combustible gases such as methane, hydrogen (H2), ethylene, ethane and acetylene may also create fires without a corresponding pressure rise. Smoking manholes are a result of incomplete gas combustion, generating toxic gases such as carbon monoxide. Each flammable gas has a lower explosive limit (LEL) and upper explosive limit (UEL) that denotes the range within which the presence of oxygen and a spark will ignite it. Generally, the LELs of these gases and mixtures thereof are about 4-5% by air volume. Where air flows through ducts and passages, oxygen can sustain the combustion of flammable gases created from pyrolysis. Carbonization of polymeric material then leaves porous surfaces which typically leads to smouldering manholes. If combustible gases continue to be generated and oxygen remains available, a fire could then ultimately lead to an explosion lasting for up to three seconds. Typical fault locations are at electrical cable splices, joints and leaking transformers containing combustible oil. Early detection of combustible gases can ultimately prevent injury to the public, utility employees, firefighters, and also prevent damage to vehicles or buildings. Damage to the underground infrastructure results in power cuts and asset damage, while pre-event accumulations of carbon monoxide may lead to building explosions. Natural gas distribution network operators (DNOs) may also be affected, as network gas lines are often run close to electrical conductors. Accurately measuring levels of flammable, toxic and odorant gases in these environments allows for early response from utility operatives to mitigate dangerous events by containing, repairing assets and scheduling maintenance thereof. Current manhole monitoring systems accomplish gas sampling and measurement, transferring data to a remote control or monitoring centre via hard-wired or wireless transmissions. However, sampling response times are often slow, especially at low LEL levels and the rate of exchange of sampled air can lead to misinformation. There is therefore required an improved method of sampling gases to control ambient airflow and more precisely detect low levels of gases of interest. Summary There is provided a gas sampling device for utility enclosures, the gas sampling device comprising a housing defining a chamber, and a gas sensor arranged to detect a property of gas within the chamber, wherein the housing comprises two gas-permeable ports, each port arranged to allow gas into and / or out of the chamber. Optionally, the gas sampling device further comprising a first fan configured to cause ambient air to flow through a first one of the gas-permeable ports. This beneficially provides a device which can increase the flow of gas into / out of the chamber of the housing, increasing reliability of gas readings and also decreasing the time it takes for the gas sensors to respond to rising concentrations of gas in the air surrounding the housing. Optionally, the first fan is located within the chamber. There is further provided a gas sampling device for utility enclosures, the gas sampling device comprising a housing defining a chamber, the housing comprising a first gas-permeable port, the port arranged to allow gas into and / or out of the chamber, and a gas sensor arranged to detect a property of gas within the chamber, wherein the gas sampling device further comprises a first fan arranged to cause air to flow through the first gas-permeable port. The fan beneficially increases air flow rate through the chamber, thereby providing more accurate gas readings that more reliably represent the gas in the utility enclosure. Optionally, the gas sampling device may comprise a second gas-permeable port, the second gas-permeable port arranged to allow gas into and / or out of the chamber. The following features apply equally to the gas sampling devices described above. Optionally, the utility enclosure may be a maintenance hole, or a sewer hole, or a manhole. The utility enclosure may also be a vault, or a service box, or a mobile vehicle. Optionally, the housing may be gas-impermeable, except for the gas-permeable port(s). The housing may be fire resistant. Optionally, the housing may be liquid-impermeable. Optionally, the gas-permeable port(s) are semi-permeable port(s), optionally each having a respective semi-permeable membrane. Semi-permeable membranes / ports are gas-permeable and liquid-impermeable. In this way, if the environment in which the gas sampling device is situated becomes flooded, liquid is kept outside of the chamber, thereby avoiding damage to the components of the sampling device within the chamber, such as the sensors. The gas-permeable membrane(s) may be located on an outwardly facing surface of the respective gas-permeable port(s). In this way, water / liquid cannot enter the port(s). The gas- permeable membrane(s) may be protected by attached grill covers which may be made from Polybutylene terephthalate (PBT). Optionally, the two gas-permeable ports may be at opposing ends of the housing. This beneficially provides a gas flow path through the chamber of the housing encouraging the gas contained within the chamber of the housing to be more quickly exchanged with gas outside the housing. The two ports allow for better gas flowthrough the chamber, providing the sensors with a sample of gas that more reliably matches the composition of the environment outside of the housing, thus resulting in a more reliable gas reading. Furthermore, better gas flow also permits for earlier detection of gas levels outside the housing which allows for a quicker response if gas levels are dangerous. Optionally, the gas sampling device further comprises a tube attached to the housing around a perimeter of a firstone of the gas-permeable ports, the tube configured to provide a gas-flow path between the first gas-permeable port and the first fan, such that the fan, when activated, causes flow of ambient air through the port and through the tube. Optionally, the tube may be cylindrical, square, or any other suitable shape. Optionally, the gas sampling device further comprises a second fan, the second fan being configured to cause ambient air to flow through a second one of the gas-permeable ports. This beneficially provides control over flow of ambient air through each of the two gas-permeable ports. Optionally, the first fan is oriented to cause air to flow into the chamber through the first port when the first fan is activated, and wherein the second fan is oriented to cause air to flow out of the chamber through the second port when the second fan is activated. This beneficially provides a device whereby gas is drawn through the chamber of the housing. Furthermore, this allows for a turnover of gas within the chamber of the housing which permits for faster sensing of changes in gas concentrations. Optionally, the gas sampling device further comprises a controller, the controller configured to control the first and second fans independently of each other. This beneficially provides a device whereby the two fans can be independently controlled, allowing for accurate control of the flow rate of gas into and out of the chamber of the housing. Optionally, the controller is configured to activate the first fan to thereby cause air to flow into the chamber through the first port, activate the gas sensor to record a measured gas property, then activate the second fan to thereby cause air to flow out of the chamber through the second port. This beneficially provides a device that can accurately sample gas from outside the chamber. Furthermore, this reduces the quantity of residual gas leftover in the system after sampling which increases the accuracy of subsequent gas sample measurements as no leftover gas remains in the chamber of the device. Optionally, the controller is configured to activate the first fan and the second fan for a time period before activating the gas sensor to record the measured gas property. This beneficially provides a device that can flush out stagnant gas from within the chamber of the housing before making any gas measurements. Running the fans before taking a measurement ensures that gas sample measurement is taken using gas representative of the outside environment. Optionally, the controller is configured to cause the gas sensor to perform a warm-up and / or calibration sequence before activating the gas sensor to record the measured gas property and / or wherein the gas sensor is configured to perform a warm-up and / or calibration sequence before recording the measured gas property. Optionally, the controller is configured to keep the first fan on while the gas sensor records the measured gas property. Optionally, the first fan is a low voltage micro fan and / or the second fan is a low voltage micro fan. Optionally, the micro fan may be less than 20mm in diameter. The low voltage micro fan may be configured to operate at less than 5V. This beneficially provides a compact device that can measure the concentration of gas. This further provides a device that requires minimal power to run and make measurements. Optionally, the gas sampling device further comprises a flood detection sensor. Optionally the flood detection sensor may comprise conductive terminals located on the outside of the housing. Optionally the flood detection sensor may be positioned beneath one of the grill covers. The flood detection sensor beneficially provides a device which can assess when the device is flooded. For example, during a flood, it is advisable to not perform gas sample measurements as the ports may be under the flood level, inhibiting the amount of gas that can enter the chamber. The flood detection sensor may be configured to inhibit gas sampling until the flood level has dropped to below a certain level, for example, below the level of the ports. Optionally, the gas sensor comprises a CO2 sensor, and / or a methane sensor, and or a temperature sensor, and / or a humidity sensor and / or a hydrogen sensor and / or an ethylene sensor and / or a hydrocarbon gas sensor and / or an ethane sensor and / or an acetylene sensor and / or a natural gas sensor and / or a natural gas odorant sensor, such as tert-Butylthiol and methyl mercaptan. Detection of natural gas odorants such as tert-Butylthiol and methyl mercaptan is advantageous, demarcating the source of natural gas in underground structures, especially for liability purposes. Optionally, the gas properties being measured could be any or all of the properties measurable by the gas sensors. This beneficially provides a device whereby a range of different gas properties may be measured, providing a user with a range of data. Optionally, the gas sensor comprises a temperature sensor, a humidity sensor and one or more additional gas property sensing modules, the gas sampling device being configured to calibrate the one or more additional gas property sensing modules, based on readings from the temperature sensor and the humidity sensor. Optionally, the gas sensor may be assembled on a circuit board. Optionally, the gas sensor may be positioned along a main gas flow path between the two gas-permeable ports. When any one of the first and second fans 18a, 18b are in operation, the flow of gas / air through the chamber 14 will be along a central path of the chamber 14. The plurality of sensors 24a d will be positioned along this path to increase the contact of gas to the sensors 24a-d such that quicker and more accurate measurements of gas concentrations can be taken. There is further provided a method of sampling gas in a utility enclosure, the method comprising: providing in the utility enclosure a housing defining a chamber, the housing comprising a first gas-permeable port, the first gas-permeable port arranged to allow gas into and / or out of the chamber, and a gas sensor arranged to detect a property of gas within the chamber, passing ambient air from the utility enclosure into the chamber, and recording a measured gas property using the gas sensor, wherein passing ambient air into the chamber comprises providing a second gas-permeable port arranged to allow gas into and / or out of the chamber, and / or activating a first fan to cause ambient air to flow through the, or one of the, gas-permeable port(s). The fan beneficially increases air flow rate through the chamber, thereby providing more reliable gas readings in the utility enclosure. Optionally, the method may be used in overground vaults, service boxed, mobile vehicles, or any other environment where gases may build up. Optionally, the first gas-permeable port and the second gas-permeable port are provided and the first fan is oriented to cause air to flow into the chamber through the first gas-permeable port when the first fan is activated, and wherein a second fan is provided and oriented to cause air to flow out of the chamber through the second gas-permeable port when the second fan is activated. This beneficially provides a system whereby gas flows through the chamber of the system, allowing for accurate measurements to be taken, providing the user with early detection of any increase in gas concentrations. Optionally, recording the measured gas property using the gas sensor occurs after activating the first fan, and the method further comprises activating the second fan to thereby cause air to flow out of the chamber through the second port after recording the measured gas property using the gas sensor. This beneficially ensures that the gas measurements are being performed on a fresh sample of gas that has been brought into the chamber of the housing. Optionally, the method further comprises activating the first fan and the second fan for a time period before recording a measured gas property using the gas sensor. This flushes the gas out of the chamber, allowing for more reliable gas measurements. Optionally, the method further comprises warming up and / or calibrating the gas sensor before recording a measured gas property using the gas sensor. This beneficially ensures that the gas measurement is accurate and reliable. Optionally, the first fan remains activated while the gas sensor records the measured gas property. Optionally, the method further comprises pausing the recording of the measured gas property and / or marking the recorded measured gas property as unreliable while a flood condition is detected. In this way, the effects of a flood on the data sampled by the gas sampling device are avoided / mitigated. Optionally, the gas sensor comprises a CO2 sensor, and / or a hydrocarbon sensor and / or a methane sensor, and or a temperature sensor, and / or a humidity sensor and / or a hydrogen sulfide sensor and / or an ethylene sensor and / or an ethane sensor and / or an acetylene sensor and / or a natural gas sensor and / or a natural gas odorant sensor, such as tert-Butylthiol and methyl mercaptan. Optionally, the gas sensor comprises a temperature sensor, a humidity sensor and one or more additional gas property sensing modules, and the method further comprises calibrating the one or more additional gas property sensing modules, based on readings from the temperature sensor and humidity sensor. Optionally, the housing may be moulded, or may be 3D printed. The methods and devices described above may be combined in any possible combination. The optional features described above are equally applicable to all of the described methods and devices and are not limited to the particular method / device with which they are described here. The essential features of any of the methods / devices described may be optional features of any other method / device described. Further features and advantages of the aspects of the present disclosure will become apparent from the claims and the following description. Brief Description of Drawings Embodiments of the present disclosure will now be described by way of example only, with reference to the following diagrams, in which:- Figure 1 shows a schematic perspective view of a device for sampling gas; Figure 2 shows a schematic cross-sectional top-down view of the apparatus of Figure 1; Figure 3 shows a schematic cross-sectional side view of the apparatus of Figure 1; and Figure 4 shows a flow chart outlining a method of sampling gas. Detailed Description A number of different embodiments of the disclosure are described subsequently. In order to minimise repetition, similar features of the different embodiments are numbered with a common two-digit reference numeral and are differentiated by a third digit placed before the two common digits. Such features are structured similarly, operate similarly, and / or have similar functions unless otherwise indicated. In order to minimise repetition, similar features of the apparatus described subsequently are numbered with a common two-digit reference numeral and are differentiated by a third digit placed before the two common digits. Such features are structured similarly, operate similarly, and / or have similar functions as previously described unless otherwise indicated. Turning now to Figure 1, there is shown a schematic perspective view of a device 10 for sampling gas. In use, the device 10 samples gas from an enclosed space where gases can build up, for example, in a manhole or sewer, or other utility enclosure. The housing 12 defines a chamber 14 therein. The housing 12 comprises a first semi-permeable port 16a that allows gas flow between the chamber 14 of the housing 12 and the space on the outside of the housing 12. The first semi-permeable port 16a comprises a first semi-permeable membrane that is gas-permeable and liquid-impermeable. The first semi-permeable membrane ensures that only the ingress of gas is allowed into the chamber 14. The housing 12 is liquid-impermeable such that no liquid can ingress into the chamber 14 through the first semi-permeable port 16a. The housing 12 is formed of polybutylene terephthalate (PBT) which is a thermoplastic material capable of withstanding temperatures of up to 150°C. The housing 12 further comprises a second semi-permeable port 16b that allows gas flow into and out of the chamber 14 of the housing 12. The second semi-permeable port 16b provides a gas flow path between the chamber 14 of the housing 12 and the space on the outside of the housing 12. The second semi-permeable port 16b comprises a second semi-permeable membrane that is liquid-impermeable, and so resistant to water, but gas-permeable. The second semi-permeable membrane ensures that only the ingress of gas is allowed into the chamber 14 through the second semi-permeable port. Furthermore, the two semi-permeable membranes on the semi-permeable ports 16a, 16b are further protected by attached grill covers 30a, 30b which are made from Polybutylene terephthalate (PBT). The advantage of having a grill attachment is it can keep away any debris that could potentially damage the semi-permeable membranes. The device 10 further comprises a first fan 18a for drawing air / gas into the chamber 14 of the housing 12. The first fan 18a is a low voltage fan rated at 5V or less. The first fan 18a is disposed about the first semi-permeable port 16a such that when it is activated, it can draw ambient air / gas into the chamber 14 through the first semi-permeable port 16a. The first fan 18a is orientated such that it draws air into the chamber 14. The first semi-permeable membrane is a Polytetrafluoroethylene (PTFE) membrane. The device 10 further comprises a second fan 18b for expelling air / gas from the chamber 14 of the housing 12. The second fan 18b is a low voltage fan rated at 5V or less. The second fan 18b is disposed about the second semi-permeable port 16b such that when it is switched on, it can expel ambient air / gas from the chamber 14 through the second semi-permeable port 16b. The second fan 18b is orientated such that it expels air from the chamber 14. The first and second fans 18a, 18b are orientated relative to each other such that they create a directional flow of ambient air / gas through the chamber 14, permitting the sensors 24a-d to accurately and quickly measure the concentration of different gases in the space surrounding the housing. The two semi-permeable membranes are disposed on an outwardly facing surface of the two semi-permeable ports 16a, 16b such that they prevent any water / liquid entering the ports. The first and second fans 18a, 18b are digitally controlled low voltage micro fans. The first and second fans 18a, 18b are less than 20mm in diameter. Turning now to Figure 2, there is shown a schematic cross-sectional top-down view of the device 10. The two semi-permeable ports 16a, 16b are located at opposite ends of the housing 12 such that air can be drawn through the chamber 14 of the housing 12. The first and second fans 18a, 18b are also located at opposite ends of the housing 12, next to their respective semi-permeable ports 16a, 16b, allowing for rapid directional flow of gas through the chamber 14. Additionally, the semi-permeable membranes on the semi-permeable ports 16a, 16b allow the housing 12 to be submerged for extended periods of time (several weeks) without ingress of water into the chamber 14. Semi-permeable ports 16a, 16b are each protected by a grill 30a, 30b. The chamber 14 further comprises a circuit board 20 attached to a bottom surface of the chamber 14. The circuit board 20 is raised from the bottom surface of the chamber 14 by spacers, such that there is a gap between the circuit board 20 and the bottom surface of the chamber 14. This reduces the likelihood of any damage to the circuit board 20 in the case of a small amount of water ingress or condensation and allows for cooling of the circuit board. The circuit board 20 comprises a plurality of gas sensors 24a, 24b, 24c, 24d. In other examples, the circuit board 20 may comprise more than four sensors depending on the particular requirements of the utility enclosure to be monitored. The sensors 24a-d comprise a temperature sensor 24a, a humidity sensor 24b and two further gas-level sensors. In this example, the gas level sensors are a hydrocarbon gas sensor 24c and a carbon dioxide sensor 24d. The sensors 24a-d are assembled on the circuit board such that they are positioned along the main gas flow path between the two semi-permeable ports 18a, 18b. When any one of the first and second fans 18a, 18b are in operation, the flow of gas / air through the chamber 14 will be along a central path of the chamber 14. The plurality of sensors 24a-d will be positioned along this path to increase the contact of gas to the sensors 24a-d such that quicker and more accurate measurements of gas concentrations can be taken. The plurality of sensors 24a-d automatically take periodic measurements, and can be controlled remotely to take measurements are requested times. The housing 12 further comprises a pair of conductive terminals 22 on an outer surface of the housing 12. The conductive terminals 22 form a flood detection sensor that can sense whether or not the housing 12 is submerged in water. When the housing 12 is submerged in water, the semi-permeable ports 16a, 16b maybe partially, or, fully blocked by the water. If this is the case, the fans 18a, 18b will be unable to draw gas / air into the chamber 14 and the measurements taken by the plurality of sensors 24a-d are likely to be inaccurate. Measurements from the conductive terminals 22 are used to disable the sampling process, and negate or flag any readings taken by the plurality of sensors 24a-d during flooding of the housing. When the flood detection sensor 22 indicates that the water level is below the level of the semi-permeable ports 16a, 16b, normal sampling cycles resume with valid gas readings. As shown in Fig. 2, conductive terminals 22 may be positioned on an end of the housing adjacent a semi-permeable port 16a, the conductive terminals being protected by protective grill 30a. Alternatively, as shown in Fig. 3, the conductive terminals may be located on a side of the housing. Turning now to Figure 3, there is shown a schematic cross-sectional side view of the device 10. As shown in Fig. 3, the circuit board 20 is propped up off of the bottom surface of the chamber 12 by spacers such that there is a gap between the circuit board 20 and the chamber 12. The plurality of sensors 24a-d are lined up on the circuit board 20 such that they are in the main flow path of gas / air between the two semi-permeable ports 16a, 16b. Turning now to Figure 4, there is shown a flow chart outlining a method of sampling gas using the device 10. At Step 100, the gas sampling and measurement cycle is started. The device 10 is partially powered up by an external controller or wakes up from sleep mode if acting as a standalone module. At Step 105, the flood sensor 22 is checked to determine if the sampling should continue, be aborted or indicate that the subsequent measurements are invalid. If water levels are deemed low enough to allow for the sampling to continue, then the sequence moves on to Step 110. A high water level can cause the sequence to stop and the device 10 to power down. At Step 110, humidity and temperature are measured using the gas sensors 24a and 24b. Extreme humidity (e.g. >90% relative humidity) may be indicative of flooding, leakage of steam from underground heating networks, or the buildup of undesirable condensate within the chamber 14 of the device 10. Under these conditions, the sequence may be aborted, or a warning of undesirable temperatures / humidity may be sent alongside the gas measurements. Ambient temperature is measured at this point and is collected as part of the overall dataset and / or used internally along with humidity readings for gas sensor calibration. If temperature / humidity readings are unsatisfactory, the sequence may be sent back to Step 100 or the device 10 may be turned off. If conditions are satisfactory, the sequence moves onto Step 115. At Step 115, the plurality of sensors 24a-d and the first and second fans 18a, 18b are turned on allowing for gas / air to be passed through the chamber 14. At Step 120, the sequence enters a waiting period to allow for sufficient gas / air to enter into the chamber 14. This permits the sensors 24a-d to warm up and stabilise. The waiting period is 8 minutes, but may vary in other examples. At Step 125, the second (exhaust) fan 18b is switched off, allowing the first (inlet) fan 18b to continue drawing air / gas into the chamber 14. This continues for 2 minutes in Step 130 of the sequence, allowing the gas sensors 24a-d to warm up. At Step 135, the plurality of gas sensors 24a-d take their respective gas measurements. The gas measurements are captured and stored for onward transmission to a server via an intermediate controller or directly via a wireless LPWAN depending on the embodiment. At Step 140, the second (exhaust) fan 18b is switched on, venting out the chamber 14. The plurality of gas sensors 24a-d are also powered down at this step. This venting period which occurs at Step 145 is designed to clear stale air / gas from the chamber 14 and will typically last approximately 1 minute. At Step 150, both the first and second fans 18a, 18b are switched off, ending the gas measurement sequence. At Step 155, the sequence may return to Step 100, commencing a new gas measurement cycle. This may occur anywhere from an hour to several weeks after the first sequence finished. The time scale between measurements depends on the monitoring requirements of the utility enclosure being monitored. Although particular embodiments of the disclosure have been disclosed herein in detail, this has been done by way of example and for the purposes of illustration only. The aforementioned embodiments are not intended to be limiting with respect to the scope of the appended claims. It is contemplated by the inventors that various substitutions, alterations, and modifications may be made to the invention without departing from the scope of the invention as defined by the claims.

Claims

1. A gas sampling device for utility enclosures, the gas sampling device comprising:a housing defining a chamber, anda gas sensor arranged to detect a property of gas within the chamber, wherein the housing comprises two gas-permeable ports, each port arranged toallow gas into and / or out of the chamber.

2. A gas sampling device according to claim 1, the gas sampling device further comprising a first fan configured to cause ambient air to flow through a first one of the gas-permeable ports.

3. A gas sampling device according to claim 2, the first fan being located within the chamber.

4. A gas sampling device according to claim 2 or 3, the gas sampling device further comprising a tube attached to the housing around a perimeter of a first one of the gas-permeable ports, the tube configured to provide a gas-flow path between the first gas-permeable port and the first fan, such that the fan, when activated, causes flow of ambient air through the port and through the tube.

5. A gas sampling device according to any of claims 2 to 4, the gas sampling device further comprising a second fan, the second fan being configured to cause ambient air to flow through a second one of the gas-permeable ports.

6. A gas sampling device according to claim 5, wherein the first fan is oriented to cause air to flow into the chamber through the first port when the first fan is activated, and wherein the second fan is oriented to cause air to flow out of the chamber through the second port when the second fan is activated.

7. A gas sampling device according to claim 6, the gas sampling device further comprising a controller, the controller configured to control the first and second fans independently of each other.

8. A gas sampling device according to claim 7, wherein the controller is configured to: activate the first fan to thereby cause air to flow into the chamber through the first port, activate the gas sensor to record a measured gas property,then activate the second fan to thereby cause air to flow out of the chamber through the second port.

9. A gas sampling device according to claim 8, wherein the controller is configured to: activate the first fan and the second fan for a time period before activating the gas sensor to record the measured gas property.

10. A gas sampling device according to claim 8 or 9, wherein the controller is configured to cause the gas sensor to perform a warm up and / or calibration sequence before activating the gas sensor to record the measured gas property and / orwherein the gas sensor is configured to perform a warm up and / or calibration sequence before recording the measured gas property.

11. A gas sampling device according to any of claims 8 to 10, wherein the controller is configured to keep the first fan on while the gas sensor records the measured gas property.

12. A gas sampling device according to any of claims 2 to 11, wherein the first fan is a low voltage micro fan and / or the second fan is a low voltage micro fan.

13. A gas sampling device according to any preceding claim, the gas sampling device further comprising a flood detection sensor.

14. A gas sampling device according to any preceding claim, wherein the gas sensor comprises a C02 sensor, and / or a methane sensor, and or a temperature sensor, and / or ahumidity sensor and / or a hydrogen sulfide sensor and / or an ethylene sensor and / or a hydrocarbon gas sensor and / or an ethane sensor and / or an acetylene sensor and / or a natural gas sensor and / or a natural gas odorant sensor, such as tert-Butylthiol and methyl mercaptan.

15. A gas sampling device according to any of claims 1 to 13, wherein the gas sensor comprises a temperature sensor, a humidity sensor and one or more additional gas property sensing modules, the gas sampling device being configured to calibrate the one or more additional gas property sensing modules, based on readings from the temperature sensor and the humidity sensor.

16. A gas sampling device for utility enclosures, the gas sampling device comprising: a housing defining a chamber, the housing comprising a gas-permeable port, the port arranged to allow gas into and / or out of the chamber, anda gas sensor arranged to detect a property of gas within the chamber, wherein the gas sampling device further comprises a fan arranged to cause air to flow through the gas-permeable port.

17. A method of sampling gas in a utility enclosure, the method comprising: providing in the utility enclosure:a housing defining a chamber, the housing comprising a first gas-permeable port, the first gas-permeable port arranged to allow gas into and / or out of the chamber, anda gas sensor arranged to detect a property of gas within the chamber, passing ambient air from the utility enclosure into the chamber, and recording a measured gas property using the gas sensor,wherein passing ambient air into the chamber comprises:providing a second gas-permeable port arranged to allow gas into and / or out of the chamber, and / oractivating a first fan to cause ambient air to flow through the, or one of the, gas-permeable port(s).

18. A method according to claim 16, wherein the first gas-permeable port and the second gas-permeable port are provided and the first fan is oriented to cause air to flow into the chamber through the first gas-permeable port when the first fan is activated, and wherein a second fan is provided and oriented to cause air to flow out of the chamber through the second gas-permeable port when the second fan is activated.

19. A method according to claim 17, wherein recording the measured gas property using the gas sensor occurs after activating the first fan, and the method further comprises: activating the second fan to thereby cause air to flow out of the chamber through the second port after recording the measured gas property using the gas sensor.

20. A method according to claim 17 or 18, the method further comprising: activating the first fan and the second fan for a time period before recording a measured gas property using the gas sensor.

21. A method according to any of claims 17 to 19, the method further comprising: warming up and / or calibrating the gas sensor before recording a measured gas property using the gas sensor.

22. A method according to any of claims 17 to 20, wherein the first fan remains activated while the gas sensor records the measured gas property.

23. A method according to any of claims 17 to 21, the method further comprising pausing the recording of the measured gas property and / or marking the recorded measured gas property as unreliable while a flood condition is detected.

24. A method according to any of claims 16 to 22, wherein the gas sensor comprises a CO2 sensor, and / or a hydrocarbon sensor and / or a methane sensor, and or a temperature sensor, and / or a humidity sensor and / or a hydrogen sulfide sensor and / or an ethylene sensor and / or an ethane sensor and / or an acetylene sensor and / or a natural gas sensor and / or a natural gas odorant sensor, such as tert-Butylthiol and methyl mercaptan.

25. A method according to any of claims 16 to 22, wherein the gas sensor comprises a temperature sensor, a humidity sensor and one or more additional gas property sensing modules, and the method further comprises calibrating the one or more additional gas property sensing modules, based on readings from the temperature sensor and humidity 5 sensor.

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