I-DN (i-Nominal Diameter) ithetha i-diameter yegama lombhobho, engumndilili wedayamitha yangaphandle kunye nedayamitha engaphakathi. Ixabiso le-DN = ixabiso le-De -0.5 * ixabiso le-tube wall thickness. Qaphela: Le ayingodayamitha yangaphandle okanye idiameter yangaphakathi.

Amanzi, umbhobho wentsimbi wothumelo lwegesi (umbhobho wentsimbi ekhandisiweyo okanye umbhobho wentsimbi ongeyiyo, umbhobho wentsimbi, umbhobho wentsimbi-yeplastiki oyintlanganisela kunye nombhobho wepolyvinyl chloride (PVC) njl.

I-De (I-Diameter yaNgaphandle) ithetha i-diameter engaphandle yombhobho, iPPR, umbhobho we-PE, umbhobho we-polypropylene idayamitha engaphandle, ephawulwe ngokubanzi nge-De, kwaye zonke kufuneka ziphawulwe njengefomu njengobubanzi obungaphandle * ubukhulu bodonga, umzekelo i-De25 × 3.

I-D ibhekisela ngokubanzi kwi-diameter yangaphakathi yombhobho.

d ngokubanzi ibhekisa kwidayamitha yangaphakathi yombhobho wekhonkrithi. Imibhobho yekonkrithi eyomeleziweyo (okanye ikhonkrithi), imibhobho yodongwe, imibhobho yodongwe enganyangekiyo kwiasidi, iithayile zesilinda kunye neminye imibhobho, edayamitha yombhobho wayo kufuneka imelwe yidayamitha yangaphakathi d (enjenge-d230, d380, njl. njl.)

Φ imele ububanzi besangqa esiqhelekileyo; inokuphinda imele i-diameter yangaphandle yombhobho, kodwa ngeli xesha kufuneka iphindwe ngobuninzi bodonga.