A steam sterilization system for a conveyor wash using a submicron filter (24) that can cope with transition from lower pressure flow of water to higher pressure flow of steam. Water flows through the submicron filter when the system is in a first operating mode, and steam flows through the submicron filter when the system is in a second operating mode. The submicron filter is such that predetermined values of steam pressure and temperature can be applied for a sustained period of time without damaging the filter, thereby avoiding reducing the efficiency of the filter.
