The ofu valvụ tree na-na chịngọm ná ntutu isi valves na efere n'elu, valves na tree efere dị ka a dum.

Main atụmatụ: nnukwu mmepụta ikike, elu tree arụmọrụ, ala tree mgbali dobe, mfe Ọdịdị, ọnụ ala, karịsịa kwesịrị ekwesị n'ihi na distillation usoro na ihe onwunwe onwe-polymerization.