Reply To: Pipe size vs. flow rate. vs. pressure drop chart wanted (water)
In reply to message posted by kook:
Looking for a chart which has pipe I.D., flow rate, and pressure drop (per 100′, for example) – to estimate water pressure drop on 450′ level run from street to house, with varying amounts of flow. Street pressure is 50-55psi.


Are we using K L or M tubing, what flow rates in GPM are we looking for and we must keep the velocity under 8 FPS.

Now for the real confusing aspect of figuring friction losses

Besides developed length what type of fittings and valves are we going to use globe Vs gate or Ball valves?

Are we going to use this supply strictly for fire suppression or domestic use or a combination of both?

Here lies the problem that design plumbers face.

Lets say we are using copper tubing and we use the NFPA standard 13 this sets the friction loss coefficient “C” for copper tube at 150

If we were to use the Hazen-Williams formulas for copper tubing the “C” factor would be 140

By using the 150 factor the results generated would be close to the D’Arcy-Weisbach or similar variations of the Fanning friction loss formula.

So here we have the same material having various friction losses by various code bodies.

If you know the exact application and material that narrows your quest considerably.

Why not contact the CDA or Steel piping institute Or if you have a United Association (U/A) apprenticeship training program near you contact the 4th year apprentice instructor as all these formulas are taught to 3rd and 4th year apprentices and they may have student hand outs (charts)

If you want send me a private E mail and possibly I can put you in contact with some of the real experts on my list who know this stuff like the back of their pencil.

Good luck


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