Nke a bụ bong kwụ ọtọ 12.9 "ogologo nwere ọnụ ụlọ abụọ. Ụlọ abụọ ahụ nwere otu ihe nzacha osisi nke ogwe aka 11. Ọ dị ka osisi perc bong ma ọ bụ ash catcher bong n'ihi na enweghị ohere ọzọ iji jide anwụrụ ọkụ. Ya mere ọ dị mfe ịnweta. a ezigbo igbu mgbe e nwere ọtụtụ osisi filter ogwe aka na anwụrụ ọkụ na-adọta n'ime ngụgụ ngwa ngwa.