Ukwazisa yethu ngokuthe ngqo ngevalve ye-diaphragm.Ukusebenza okugqwesileyo, ukuthembeka kunye nokuguquguquka kwesi sivalo esisingqinisiso sikwenza kube yinto eyimfuneko yokusetyenziswa kokuphathwa kwamanzi ngokukodwa kwishishini lokulungisa imigodi.