DN (Nominal Diameter) zvinoreva dhayamita yepamusoro yepombi, inova avhareji yedhayamita yekunze nedhayamita yemukati. Kukosha kweDN = kukosha kweDe -0.5*kukosha kwehukobvu hwemadziro echubhu. Cherechedza: Iyi haisi dhayamita yekunze kana dhayamita yemukati.

Pombi yesimbi inofambisa mvura, yegesi (pombi yesimbi yakavharidzirwa kana pombi yesimbi isina galvanized), pombi yesimbi yakakandwa, pombi yesimbi-purasitiki yakasanganiswa uye pombi yepolyvinyl chloride (PVC), nezvimwewo, zvinofanira kunyorwa se "DN" (yakadai seDN15, DN50).

De (Kunze kwedhayamita) zvinoreva dhayamita yekunze yepombi, PPR, PE pombi, dhayamita yekunze yepombi yepolypropylene, inowanzo nyorwa neDe, uye zvese zvinoda kunyorwa sechimiro chedhayamita yekunze * ukobvu hwemadziro, semuenzaniso De25 × 3.

D inowanzoreva dhayamita yemukati mepombi.

d inowanzoreva dhayamita yemukati mepombi yekongiri. Mapombi ekongiri akasimbiswa (kana kongiri), mapombi evhu, mapombi eceramic anodzivirira acid, mataira ecylinder nedzimwe pombi, dhayamita yepombi inofanira kumiririrwa nedhayamita yemukati d (yakadai se d230, d380, nezvimwewo)

Φ inomiririra dhayamita yedenderedzwa rakajairika; inogonawo kumiririra dhayamita yekunze kwepombi, asi panguva ino inofanira kuwanziridzwa neukobvu hwemadziro.