How much water in a copper tube?

I found a formula for the different sizes on google.

ID x ID x .7854 x length = volume

Rich

I made up a little spread sheet. It assumes 1/32" wall on the pipe.

OD ID Area cu-in cu-ft cu-ft per ft per ft per 100 ft

I had to replace the copper pipes in my slab. I ran the new ones in a channel chiseled in the slab to get passed doors. For the heating system, I used 3/4" thick-wall copper pipe and wrapped it in duct tape to prevent future corrosion. The fresh water runs are 3/4" to laundry and kitchen, and 1/2" for the rest. The run to one bathroom is approximately 75 feet. It takes about 30 seconds to start getting the hot water at the end.

Pipe is measured by ID, not OD. Tubing is measured by OD.

Wayne

Dear William - Thanks for the chart. I appreciate all the work. Does that mean 100 feet of 3/4 inch holds .282 gallons?

(ID/2) x 3.1416 x (pipe length)

Just guessing.....

tom

(ID/2)^2 x 3.1416 x (pipe length)

Sorry to square the radius.

So should be radius squared times pi times length of straight tube.

hth,

tom

Yes, we do.

No. That's CUBIC FEET. Gallons per 100 ft are: 0.9, 2.1, 0.2

LOL. I was somewhat surprised to see Harry get all of the help he did get, after that remark. Now. Who's he going to get to do the work? ;o)

... This is a good group of people.

Not a good guess. The formula is A = pi * radius SQUARED, not pi * radius / 2.

-- Regards, Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt. And who wants to leave buttprints in the sands of time?

People can sense honestly. :-)

I really like this group - no one ripped me - and I got great answers. Now I must decide whether I want to run 100 feet of 1/4 inch - 1/2 inch

- 3/4 inch to a kitchen sink and dishwasher 100 feet away from the tankless water heater. The tube will be overhead and insulated.

Opinions on that?

Harry

That is a common misconception Try taking a ruler to 1/2" nominal Schedule 40 pipe sometime.

Pipe of the same nominal size is the same OD regardless of schedule, but the nominal size is always less than the actual OD, and usually less than the ID too. It may be that the nominal sizes were established by taking the ID of schedule 40 pipe and subtracting some nominal allowance for accumulated scale but I have never seen that in writing anywhere.

However tubing IS measured by the OD and the nominal size is the same as the OD.

Like you, I am to lazy to look it up, but 1/4" will not provide much volume of water. Use 1/2" or 3/4" so you dont have to wait 1/2 hour to fill your sink. And since you are going overhead you can insulate the pipe at the same time. You may experience water hammer with the 1/4" also.

this thread is sad.... thank the american public education system.

randy

Refigeration tubing is ID, Plumbing pipe is sized by OD.

Good point Eddy. I think I will just buy a coil of 1/2 inch flexible copper and run that from the tankless water heater to the kitchen sink. The dishwasher gets its water from the kitchen faucet tap. Harry