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larrygman
12-03-2008, 05:49 PM
Does anyone know how many feet of 1/2" pex does it take to hold 1 gallon of water?? kinda crazy question but cant fig it out..

Thanks

Lar

seaneys
12-03-2008, 06:02 PM
Well, a quick scan if sites indicates the ID is 0.475 inches...

The volume would be Vpex = Lpex * Pi * (0.457)**2 / 4...

I do not recall the number of cubic inches in a galllon off hand.

Stee

sjsmithjr
12-03-2008, 06:27 PM
I do not recall the number of cubic inches in a galllon off hand.

1 cubic inch is about 0.004 gallons. To answer the original question, it would take about 118 feet of 1/2 inch pex to hold 1 gallon of water.

99k
12-03-2008, 06:35 PM
a=3.14*.24*.24
a=.181 sq in

1 gal= 231 cu in

231/.181 = 1276 inches or 106 ft of pipe

sjsmithjr
12-03-2008, 07:19 PM
a=3.14*.24*.24
a=.181 sq in

1 gal= 231 cu in

231/.181 = 1276 inches or 106 ft of pipe

Made me check my math. Using an ID of 0.457 inches, 106 feet of pipe would hold about .9 gallons. Try recalculating without rounding the pipe radius or pi and you'll get something closer to 118 feet.

larrygman - out of curiosity, why to you ask?

99k
12-03-2008, 07:24 PM
Made me check my math. Using an ID of 0.457 inches, 106 feet of pipe would hold about .9 gallons. Try recalculating without rounding the pipe radius or pi and you'll get something closer to 118 feet.

Hey Sam, the numbers are close enough for me:D I used a pipe I.D. of .475 (rounded to .48 ) which was given ... I did not actually measure it.

sjsmithjr
12-04-2008, 01:02 PM
So I got to work and pulled a spec sheet for Zurn pex. The i.d. for 1/2" pex is given as .475 inches (118 feet) with a fluid capacity of 0.0092 gal/ft (108 feet).

I suppose the correct answer is that if you need something to measure a gallon of water with, don't use small diameter pex tubing:rolleyes:

I think I'll be better off when things pick up a bit and I stop spending time on such trivial matters...

99k
12-04-2008, 01:45 PM
I think I'll be better off when things pick up a bit and I stop spending time on such trivial matters

Yes, this is a sure sign that both of us have too much time on our hands:D

larrygman
12-04-2008, 03:34 PM
Thanks for all the info. I was asking because I am installing a pex floor system in an addition. I wanted to check the amount of water in the tubing to make sure I have plenty of capacity in the storage tank. This is my third and largest job of this kind. The others have worked out fantastic. I have installed them with a water heater where the customer doesnt have a boiler. Of course all the bells still have to go on pump, expansion tank, relay kit on and on. but in the end they are working great.

Thanks ,

Lar