Water Supply Sizing Formula

[Blackbeard]

It was in the old code book. Threw the old codebook out. Now I don't have the formula. Need a simple no-nonsense formula I can print out for class. Anybody know where I can find one without having to buy a $50 plumbing math book to get one lousy formula?

I'm also putting together my class for next semester. Any suggestions on content would be appreciated. The guys in class have varied levels of skill. Some of them don't even know how to sweat pipe. Some of them have been in the field for many years and take my class as a refresher. Always looking for ideas to improve my classes. I can't get too fancy though. The college is poorly funded. We don't even have a wet lab. So I have to make do with what I have available.

[Lori & Dean Wigmore]

Blackbeard, you might try checking out the National Research Council website at

This is the outfit that publishes the Canadian Plumbing Code, and there's a table in the CPC that identifies line sizing based on longest run, pressure, and elevation. Not exactly what you're looking for, but maybe will help? In any event, I'm not sure that the website will even give you any information. If not, and you're interested in a copy of the table, e-mail me directly, and I'll make sure you get it.

Dean

[Mark Monson]

I don't know if this is what you want but a simple formula helpful for pipe sizing is flow capacity increases as the ratio of square of diameter increase.

D squared / d squared = flow increase factor

Where D is the larger pipe diameter and d is the smaller pipe diameter.

For example, if a 2 inch diameter pipe flows 20 gallons per minute at a certain pressure, what will the same length 4 inch pipe at the same pressure?

4 squared / 2 squared = increase factor times 20

16 / 4 = 4 times 20 = 80

Doubling the pipe diameter increases flow by a factor of 4.

MM