Ngenxa yokuba ukutya okuphekiweyo kukwimo yokupholisa ivacuum, indlela yokuhambisa ubushushu iqhutywa ukusuka kumbindi wokutya ukuya kumphezulu, ngoko umgangatho wokuthungwa kweziko lokutya awuyi kutshatyalaliswa kwinqanaba lobushushu obuphezulu, kwaye ukutya okupholileyo kuya kuba kutsha kwaye ukuhlafuna ngakumbi.Emva kwexesha lokupholisa kwe-vacuum kwangaphambili lifikelela kwiqondo lobushushu elisezantsi, ibhokisi ye-vacuum ye-pre-cooler ityhilwa ngaphandle ukuze ingene kwinkqubo elandelayo: ukupakishwa kwe-vacuum.
Ivacuum yokutya okuphekiweyo yangaphambi kokupholisa sisixhobo sokupholisa esifanelekileyo sokutya okuphekiweyo okunobushushu obuphezulu (okufana neemveliso eziqhotsiweyo, iimveliso zesosi, isuphu) ukuze kuphole ngokukhawuleza nangokulungeleleneyo, kwaye kususwe ngempumelelo iintsholongwane eziyingozi.