Multi-layer foil sampling bags are made of multi-layer foil film, which is formed by the polymer film and aluminum foil. Multi-layer foil bags are ideal for containing low molecular weight gases. The 2 layers of aluminum film provide a great barrier to gases permeating through the walls of the bag. Multi-layer foil sampling bags can be applied to collect Hydrogen (H2), oxygen (O2), nitrogen (N2), methane (CH4), carbon monoxide (CO), carbon dioxide (CO2), industrial gas, petrochemical gas and air. The continuous service temperature is from -30°C to 60°C. Multi-layer foil sampling bags are reusable. Pure air or pure nitrogen can be used for cleaning bags.