. The vent filter with a CO2 trap is designed to protect highly sensitive stored pure water from possible contaminants in the environment. These include carbon dioxide, particles, micro-organisms and volatile organic compounds that mainly come from the laboratory atmosphere.. Vent filters contain a combination of purification media carefully selected to remove airborne contaminants that could degrade purified water quality during storage.. The reservoir filters cartridges are constructed from polypropylene, polyether sulfone and styrene-acrylonitrile resin.. Carefully assembled following a dichloromethane free process.