Ivalve yokhuseleko sisixhobo sokhuseleko esisivula ngokuzenzekelayo ukukhulula uxinzelelo xa uxinzelelo ngaphakathi kwetanki yokugcina i-tetroleum yerhasi yegesi. Itanki yokugcina i-tyroleum ye-petroleum kufuneka isebenzise i-valves egcwele intwasahlobo.