1. xa isibonakaliso somthombo okanye umqondiso usilela, okanye xa izinto eziphambili zokuphumeza ii-arhente (ezifana ne-diaphragms, imithombo, izitywina, ukuhanjiswa, njl njl) zonakaliswe, kwi-manual operation automatic operation, sebenzisa i-handwheel iyaqhubeka nokugcina umsebenzi wokulawula we-valve.
2. Ivili lesandla linokusetyenziswa njengomgcini wohambo lwevalvu xa ivalve yokulawula uxinzelelo lwezero ivuliwe okanye ivaliwe, ukuba inkqubo ifuna iimali ezincinci zevalve yokulawula ukuhamba, ivili lesandla lingasetyenziselwa ukufezekisa injongo.
3. i-bakelite handwheel inokuphucula ukuthembeka kokusebenza kwevalve yokulawula, ivalve elawulayo njenge-bypass eyongezelelweyo, iindleko zotyalo-mali, kwaye igubungela indawo, xa i-aperture inkulu okanye xa usebenzisa isinyithi esinqabileyo esibiza kakhulu, iindlela zevili ezisetyenzisiweyo kwiindleko zotyalo-mali kwaye igubungela indawo yokuqwalasela, kukuthenga okulungileyo.
