I-DN (Ububanzi Obujwayelekile) isho ububanzi obujwayelekile bepayipi, okuyisilinganiso sobubanzi bangaphandle kanye nobubanzi bangaphakathi. Inani le-DN = inani lika-De -0.5*inani lobukhulu bodonga lwepayipi. Qaphela: Lokhu akulona ububanzi bangaphandle noma ububanzi bangaphakathi.

Amanzi, ipayipi lensimbi elidlulisa igesi (ipayipi lensimbi eligayiwe noma ipayipi lensimbi elingagayiwe), ipayipi lensimbi elibunjiwe, ipayipi elihlanganisiwe lensimbi-ipulasitiki kanye nepayipi le-polyvinyl chloride (PVC), njll., kufanele libhalwe ngobubanzi obujwayelekile "DN" (njenge-DN15, DN50).

I-De (Ububanzi Bangaphandle) isho ububanzi bangaphandle bepayipi, i-PPR, ipayipi le-PE, ububanzi bangaphandle bepayipi le-polypropylene, ngokuvamile obuphawulwe ngo-De, futhi konke kudinga ukuphawulwa njengohlobo lobukhulu bodonga * ububanzi bangaphandle, isibonelo i-De25 × 3.

U-D ngokuvamile ubhekisela kububanzi bangaphakathi bepayipi.

I-d ngokuvamile ibhekisela kububanzi bangaphakathi bepayipi lekhonkrithi. Amapayipi ekhonkrithi aqinisiwe (noma ekhonkrithi), amapayipi obumba, amapayipi e-ceramic amelana ne-asidi, amathayili esilinda kanye namanye amapayipi, ububanzi bawo bepayipi okufanele bumelelwe ububanzi bangaphakathi d (njenge-d230, i-d380, njll.)

U-Φ umele ububanzi besiyingi esivamile; ungamela futhi ububanzi bangaphandle bepayipi, kodwa kulokhu kufanele buphindwe ngobukhulu bodonga.