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I-valve engu-508 yokukhululwa kwe-pressure vacuum ifaneleka ukuhlelwa phezulu kwendawo yokugcina umlotha, endaweni yokugcina umlotha, i-expressure ekhishwayo kanye nezinguquko zomswakama ongavamile, ukuvikela ukugcinwa komlotha ekucindezelweni okweqile nokungalungile, iyithuluzi lokuvikela elibalulekile ukugcinwa komlotha.