Refrigerated delivery vehicles: device facilitates door closing

The doors of small air-tight refrigerated delivery vehicles can prove difficult to close, as rapid door-closing movements compress a certain amount of air, thus causing resistance. In order to avoid unwanted temperature rises due to awkward door closing, an EPDM valve has been designed by the German company Maagtechnic. It opens very rapidly when exposed to excessive air pressure, and closes very quickly as soon as pressure is adjusted. EPDM (ethylene propylene diene monomer rubber) has 80-Shore-A  hardness, good recoil-pressure values, remains flexible at temperatures as low as -20°C and resists ageing and UV rays. The 1.5 mm-thick membrane has three incurved seals situated at 120° intervals strengthened by reinforcing ribs that help the seals close rapidly after openings. The brief suction occurring once overpressure has been eliminated further assists closing.