Max safe water flow in copper pipe

Bruce Marshall

Here are some flow rates through pipe at 60 PSI
1/2" 10 GPM
3/4" 16 "

Jon_10

Max flow of water in copper pipe

Had a question put to me "In a domestic hydronic water system , what is the max flow through various sizes of copper pipe?" Jon

Bruce Marshall

Here are some flow rates through pipe at 60 PSI:

1/2" - 10 GPM 3/4" - 16 GPM

1.00" - 25 GPM 1.25" - 41 GPM

1.50" - 55 GPM 2.00" - 84 GPM

2.50" - 115 GPM 3.00" - 165 GPM

Hope this helps you.

Mike E_2

This is from a Bell & Gossett document that I have

copper

1/2 - 1.5gpm

3/4 - 4gpm

1 - 8gpm

1 1/4 - 14gpm

1 1/2 - 22gpm

2 - 45gpm

Michael

ALH_4

Velocity

Based on a 4.5 ft/s maximum allowable velocity and a 2 ft/s minimum velocity, this Excel file will let you know what pipe sizes are appropriate for a given flow rate. There are probably better tools, but this is what I use for quick calcs. I have a more complex version that calculates head loss using Hazen-Williams and Darcy-Weisbach w/Colebrook methods, but it's probably not that user-friendly. I think it's ok, but other people probably wouldn't.

Pipe sizes are nominal, not actual. Too many different ID's to account for them all. If you want to know actual velocity with a particular ID you can type it into the upper part in the blue fields. It's all pretty basic, but it's useful for quick checks.

Hope this helps,

-Andrew

Greg Gibbs

Way to

cool! Andrew

Perry_2

In the HX industry the maximum safe velocity for copper is...

In the HX industry the maximum save velocity for copper tubing is 7 Ft/second. There are litereally millions of copper tubed heat exchangers out there - and have been for many decades.

I have seen the results from long term operation at 9 ft/second and its not pretty.

Admittedly, copper can handle higher flows for short periods of time - but if you are going to run the flow constantly for a long time - 7 Ft/second has proven to work; and 8 Ft/second has proven to fail.

Perry

Plumb Bob

8 ft per sec is just over 5 miles per hour. I'm sure youre right, but it doesn't seem like 5mph would be so serious. What happens to copper pipe at 8ft/sec?

Perry_2

Localized errosion

you get gouges or pits erroded into the tube. The problem is that you only have for example 8 ft/second AVERAGE flow. You can have localized flow higher and lower than that (especially at fittings and elbows - and some HXs are built with soldered fittings to create a U-bend).

In many HX's the turbulance caused by the water entering the tubes at the face of the tubesheet is enough to errode the copper tube if average velocity is too high.

I see no reason why all the same effects would not occur in copper tubing used for water systems.

At least you don't have to deal with worse problems casued by zebra mussel shells or other debris from a raw water system. That just makes it worse.

Perry

Brad White_152

But those values are

for heating piping, where the energy to move the water is generated at your expense by your circulator.

Domestic water flows are typically much higher. (More to the point, heating piping is much lower!)

Perry_2

Keep in mind that Domestic water is

only used intermittently. Copper can handle short periods of higher velicites.

I do not have time to convert the above GPM's to Ft/second. Generally assume that the tube wall is 0.049" for an approximation if you want to calculate velocity (althoug by 1" or larger I'd not be surprised if it was 0.065" wall).

Perry