Gas protection
From Wikipedia, the free encyclopedia
Gas protection is the prevention or control of the penetration of hazardous gases into buildings or other types of real property. It usually involves either blocking entry pathways or removing the source of the gas.
Methane (which is flammable at 5-15% by volume in air) and carbon dioxide (which is toxic) are the most relevant gases, especially following two gas explosions in the 1980s in Loscoe and Abbeystead, England.[1]
UK regulatory bodies such as Building Research Establishment, British Standards, the Department of Environment, and others in the construction industry have developed and published guidance for preventing such gasses from entering buildings. Their production in the environment is associated with coal seams, deposited river silt, sewage, landfill waste, and peat.
In the case of landfill gas migration, gas is produced by organic materials in the waste degrading over time. Typically 40% carbon dioxide (CO2) and 60% methane (CH
4) by volume, this gas can be heavier than air or lighter depending on the concentration (which varies from time to time), but will move from an area of high pressure to one at a lower pressure irrespective of its relative density.
Usage
Systems to prevent gas ingress include a passive barrier or, less commonly, an active system. Passive systems utilize a barrier with low permeability, such as a membrane. Active systems are mostly employed on commercial properties because of the associated costs. There are two main practical types of active systems to prevent the ingress of gases into buildings: positive pressurization, and forced ventilation.[2]
