Umsebenzi wobugcisa: Iindidi ezisibhozo eziqhelekileyo zeevalvu, zenziwe lula kakhulu.Isitshixo sombala: inxalenye engwevu ngumbhobho apho ulwelo luhamba khona;inxalenye ebomvu yivalve kunye nomqheba wayo okanye ulawulo;iintolo eziluhlaza zibonisa indlela ivalve ehamba ngayo okanye i-swivels;kwaye umgca omthubi ubonisa indlela ulwelo oluhamba ngayo xa ivalve ivuliwe.

Iindidi ezininzi ezahlukeneyo zeevalvu zonke zinamagama ahlukeneyo.Ezona zixhaphakileyo libhabhathane, inkuku okanye iplagi, isango, iglowubhu, inaliti, ipapa, kunye nespool:

• Ibhola: Kwivalve yebhola, ingqukuva enomngxuma (ibhola) ihlala iqinile ngaphakathi kumbhobho, ivalela ngokupheleleyo ukuphuma kwamanzi.Xa ujika isiphatho, yenza ukuba ibhola ijike ibe ngamadigri angamashumi alithoba, ivumela ulwelo ukuba luqukuqele phakathi kwayo.

• Isango okanye i-sluice: Iivalvu zesango zivule kwaye zivale imibhobho ngokuthoba amasango esinyithi kuwo wonke.Iivalvu ezininzi zolu hlobo ziyilelwe ukuba zivuleke ngokupheleleyo okanye zivaleke ngokupheleleyo kwaye zisenokungasebenzi kakuhle xa zivuleleke ngokuyinxenye.Imibhobho yonikezelo lwamanzi isebenzisa iivalvu ezinje.

• Iglobhu: Iitephu zamanzi (iimpompo) ziyimizekelo yeevalvu zeglowubhu.Xa ujika isiphatho, ujija ivalve phezulu okanye ezantsi kwaye oku kuvumela amanzi acinezelekileyo ukuba ahambe ngombhobho aphume nge spout engezantsi.Ngokungafaniyo nesango okanye i-sluice, ivalve efana nale inokusetwa ukuze ivumele ulwelo olungaphezulu okanye olungaphantsi kwayo.