Kukho iindawo ezahlukahlukeneyo zengxowa yokupakisha, njenge-valve yomoya, esetyenziswa ngokubanzi kwisikhwama sokupakisha ikhofi ukuqinisekisa ukuba ikhofi ngaphakathi "iphefumula".Umzekelo, uyilo oluqhelekileyo lokubamba lomzimba womntu lusetyenziswa ngokubanzi kwizinto ezinzima.kwipakethe.