Plastics drum for storing fluids, with a pressure equalising lid - includes permeable plastics membrane which permits the passage of gas but not liquid

摘要

Plastic drums for storing and transporting liquids are sealed by means of a plastic membrane between the lid of the drum and the contents. The perforated membrane is permeable to air and impermeable to water and is clamped between the body and the lid of the drum so that an air space is present between the liq. and the membrane and between membrane and lid. Where the membrane passes between the drum and the lid, folds are created which do not permit the passage of fluid from the inside of the drum beneath the membrane but allow has to pass into or out of the space between membrane and lid. The space between fluid and drum lid may be divided by the membrane so that the greater space is either above or below the membrane. Pref. the membrane consists of a plastic cylinder or hose with a dia. greater than that of the drum (by a factor of 1.01 to 1.3 times the drum dia.) and a depth of between 0.1 and 0.25 m. The membrane consists then of that part of the cylinder wall trapped inside the drum and the end sheet of the cylinder.