Igama elithi "3/4 inch tube" ngokuvamile libhekisela kububanzi obungaphandle (OD) beshubhu. Ukuze unqume ubukhulu bangaphakathi (ID), udinga ulwazi olwengeziwe njengokuqina kodonga. Ububanzi bangaphakathi bungabalwa ngokukhipha kabili ubukhulu bodonga ukusuka kububanzi obungaphandle. Akunakwenzeka ukunquma ubukhulu bangaphakathi obuqondile beshubhu engu-3/4 intshi ngaphandle kokwazi ubukhulu bodonga.