Ngophuhliso olukhawulezayo lweshishini, ishishini levalvu liye lakhula ngokukhawuleza. Amo
ng iintlobo ezininzi zevalve, iivalvu itshekhi zisetyenziswa ngokubanzi kwiinkqubo ezahlukeneyo zolawulo lwe-fluid ngenxa yemisebenzi yazo eyodwa. Nangona kunjalo, phambi koluhlu olubanzi lweemodeli zevalve yokukhangela kwimarike, indlela yokukhetha eyona ifanelekileyo kwiimfuno zabo zobunjineli ibe yingxaki kwiinjineli ezininzi. Eli nqaku liza kukunika uhlalutyo oluneenkcukachaImodeli yevalve yaseTshayinaisikhokelo sokukhetha, ukukunceda ukuba uthenge ngokulula.