DN (Dheerkulbeegga Magacaaban) macnaheedu waa dhexroorka magacaaban ee tuubada, kaas oo ah celceliska dhexroorka dibadda iyo dhexroorka gudaha. Qiimaha DN = qiimaha De -0.5*qiimaha dhumucda derbiga tuubada. Fiiro gaar ah: Tani ma aha dhexroorka dibadda iyo dhexroorka gudaha.

Tuubada birta ee biyaha, gaaska lagu gudbiyo (tuubada birta galvanized ama tuubada birta aan galvanized ahayn), tuubada birta la shubay, tuubada isku-dhafka ah ee birta-balaastigga ah iyo tuubada polyvinyl chloride (PVC), iwm., waa in lagu calaamadeeyaa dhexroorka magaca "DN" (sida DN15, DN50).

De (Dhexdhexaadka Dibadda) macnaheedu waa dhexroorka dibadda ee tuubada, PPR, tuubada PE, dhexroorka dibadda ee tuubada polypropylene, guud ahaan lagu calaamadeeyay De, dhammaantoodna waxay u baahan yihiin in loo calaamadeeyo qaabka sida dhexroorka dibadda * dhumucda derbiga, tusaale ahaan De25 × 3.

D guud ahaan waxa loola jeedaa dhexroorka gudaha ee tuubada.

d guud ahaan waxa loola jeedaa dhexroorka gudaha ee tuubada shubka. Tuubooyinka shubka (ama shubka) ee la xoojiyay, tuubooyinka dhoobada ah, tuubooyinka dhoobada ah ee aashitada u adkaysta, taayirada dhululubada iyo tuubooyinka kale, kuwaas oo dhexroorkooda tuubooyinka ay tahay in lagu matalo dhexroorka gudaha ee d (sida d230, d380, iwm.)

Φ waxay u taagan tahay dhexroorka goobada caadiga ah; waxay sidoo kale matali kartaa dhexroorka dibadda ee tuubada, laakiin markan waa in lagu dhuftaa dhumucda derbiga.