METHANE (CH4) SAFETY WARNINGS
WARNING! There is a possibility of smelling gas prior to the apparatus giving an alarm.
This situation does not necessarily indicate a failure of the device.
The conditions under which combustion occurs are variable and depend on gas concentration. When the concentration of gas is between the LEL (Lower Explosion Limit) and UEL (Upper Explosion Limit) and there is a source of ignition, the gas mixture will burn and explode. Each apparatus is specifically designed and calibrated for a specific gas hence, it is essential that an apparatus, calibrated for one gas, is not used to detect another.
SOURCES OF METHANE (CH4) GAS LEAKS
The most likely origins for leaks in domestic premises are appliances and the connections between appliances and fixed installations of the building. Appliances are the more common origin of leaks because they may be moved and suffer damage. Another cause of gas release, especially if cookers or boilers without flame failure control are in use, is the extinction of the flame, or it non-ignition, whether by spilling of liquid, or draughts. The fixed distribution system inside the building, assuming that it has been correctly installed, and tested, is usually gas-tight as long as the building integrity is maintained or the pipes are not damaged by works, shocks, etc. Except when landslide may damage the building, a leak on these installations is very unlikely. It is possible that gas may penetrate inside a building by migrating along pipes or cables from a leak in the mains. In this case, gas may be released in any ground-floor or underground room in the building depending on the leak’s position and the underground structure, etc. There is a possibility that the gas detector will be located in another room where there is no significant gas concentration and therefore will not detect the gas. In the majority of the cases, gas will be released at low pressure, even if the flow is high hence the effect of pressure on its dispersion behavior will be unimportant.