[superplumber]

Hello I need to know how to figure how many gallons of water do I have to poure into a
10" diameter pipe to get 5 pounds of head pressure? Thanks

[speedball1]

For every foot of height add .434 PSI. Your 10" pipe doesn't figure into the equation. It could be 10 inches or 10 feet in diameter and the head preassure would still be the same. Sooooo, It would be 5 X .434 PSI or 2.17 feet.
Why are you asking? Regards, tom

[rick4747]

SPEEDBALL, you are right on the money except that you need to divide instead of multiply. So 5 / .434 =11.52 feet. SUPERPLUMBER if you still need to know how many gallons of water it would take to fill up 11.52 ft. of 10" diameter pipe it takes 4.080 gals. of water to fill a 10" pipe one foot. So 11.52 X 4.080 = 47 gals. Hope I did the math right.

[speedball1]

Rick, Superplumber asked a "working question" and I gave him a "working answer" What you didn't know was why Super plumber wanted the information . I was contacted by E-Mail with his problem. I was faced with the same problem a few times and that was blocking off and running a 5 PSI test on a section of a drainage system. I think you might have made a mistake by dividing .434 instead of multiplying it. Do the math! If 1 foot of raise will give you .434PSI of head pressure then 5 times that will give you 2.17 feet of head pressure that measures 5 PSI at the base.
With my way I do it in my head. I multiply .434 by the amount of PSI that the inspector wants to see. This gives me the anount of head that I' ll need to fill up the job with. In Superplumbers case it was a little over 2 feet This formula holds true no matter how many branches or stacks that are blocked off or how much volume that you have to fill. All you have to do is fill from the base and fill to the mark you've made. Simple and easy. Regards tom

[KISS]

Actually, there wasn't enough information to solve the problem. 10" is what schedule 40 or 10" ID. The schedule of the pipe or the problem should have been specified as ID. e.g. To fill a 10" ID pipe or fill a 10" schedule 40 pipe.

Nominal Pipe Size - Wikipedia, the free encyclopedia

With most pipes being schedule 40, your pretty much bang on: 10.75-(20.365) = 10.02. 0.365 is the wall thickness and 10.75 id the OD.

Just splitting hairs. Sorry.

[speedball1]

This wasn't a test question and I'm a "rule of thumb and seat of the pants sort of guy" so I just gave him the easiest answer. Thanks for "fleshing" it out. Regards, Tom

[SC-tbfd]

If both answers are correct why is one 2 feet and the other is 11 feet. I'm confused :confused:

[speedball1]

if both answers are correct why is one 2 feet and the other is 11 feet. i'm confused :confused:

I stand corrected. Math isn't one of my strong points so I posted the question up and a math guy sent this back. Because I was so busy and the question had been answsered to Superplumbers satisfaction I just copied and pasted his answer up whithout checking. My first answer is correct. You figure head pressure in feet by multiplying .434 times the amount of head pressure that you wish to achieve. Soooo, 5 X .434= 2.17 feet. I'm going back and correct or delete the misinformation. Thanks for being so observant. Tom

[caibuadday]

Hello I need to know how to figure how many gallons of water do I have to poure into a
10" diameter pipe to get 5 pounds of head pressure? thanks

assuming you have a true 10 in D pipe, and it is a true vertical pipe. Your Q required 3 parts answer
5psi/ 0.433 =11.55 ft=138 in
V= A x H, V=5 x 5 x 3.14 x 138=10833 in3, 10833/1728= 6.27 ft3
6.27 x 7.48= 47 gal

[speedball1]

assuming you have a true 10 in D pipe, and it is a true vertical pipe. Your Q required 3 parts answer
5psi/ 0.433 =11.55 ft=138 in
V= A x H, V=5 x 5 x 3.14 x 138=10833 in3, 10833/1728= 6.27 ft3
6.27 x 7.48= 56 gal

Whoa! I'm really impressed with your math but not your reasoning. His question was

I need to know how to figure how many gallons of water do I have to poure into a 10" diameter pipe to get 5 pounds of head pressure?

Now if you pour 56 gallons of water into a 10" dia. Pipe how high will the pipe have to be to accept those 56 gallons? Since one foot of height equals .434 of head pressure and he's asking for a five pound head pressure this works out to.( even a math dummy like me can multiply 5 X .434 = 2.17 to give you a little over two feet of height to achieve 5 PSI of head pressure.) Now comes the interesting part. I want to watch you pour 56 gallons of water into a 10 inch dia. Pipe that's a little over two foot tall. Sort of like jamming 10 pounds of crap in a 5 pound bag. Or do you wish to argue the .434 thingy? Hey! It's been a long day and I'm just having a bit of fun. Don't git yo knickers in a snit but if I'm wrong come on back with better math. Ps. I'm still impressed with your figures. Cheers, Tom

[Capuchin]

Tom, I think you're fudging the maths here! :)

I don't know much about plumbing terms so please call me out on it:

Assuming 5 pounds of pressure on the head is 5PSI, and your 0.434 is in units of PSI per FOOT, and using the data you gave before then:

Dimensional analysis shows us that multiplying gives us:

This is not what we want, we want an answer in ft.

So we see that dividing gives:



which is what we want.

So calculating we get:



with 10" pipe (assuming that is the internal diameter), we find that this is cubic inches of water, which is 177 liters, or 39 imperial gallons.

Hope that clears this up. Please check me for errors.

Edit: Tom, your math would calculate what pressure a 5 ft tall pipe would give: about 2.17 PSI. I hope that helps you to see where you were making a mistake.

[caibuadday]

Whoa!! I'm really impressed with your math but not your reasoning. His question was
Now if you pour 56 gallons of water into a 10" dia. pipe how high will the pipe have to be to accept those 56 gallons? Since one foot of height equals .434 of head pressure and he's asking for a five pound head pressure this works out to.( even a math dummy like me can multiply 5 X .434 = 2.17 to give you a little over two feet of height to achieve 5 PSI of head pressure.) Now comes the interesting part. I wanna watch ya pour 56 gallons of water into a 10 inch dia. pipe that's a little over two foot tall. Sorta like jamming 10 pounds of crap in a 5 pound bag. Or do you wish to argue the .434 thingy?? Hey! It's been a long day and I'm just having a bit of fun. Don't git yo knickers in a snit but if I'm wrong come on back with better math. Ps. i'm still impressed with your figures. Cheers, Tom

OK OK... I put the wrong 56gal... but it is still 11.55 ft H... ps 0.433 psi per ft height... 8.33 lb per gal... one ft3 get about 7.48 gal

[SC-tbfd]

Tom, I think you're fudging the maths here! :)

I don't know much about plumbing terms so please call me out on it:

Assuming 5 pounds of pressure on the head is 5PSI, and your 0.434 is in units of PSI per FOOT, and using the data you gave before then:

Dimensional analysis shows us that multiplying gives us:

This is not what we want, we want an answer in ft.

So we see that dividing gives:



which is what we want.

So calculating we get:



with 10" pipe (assuming that is the internal diameter), we find that this is cubic inches of water, which is 177 liters, or 39 imperial gallons.

Hope that clears this up. Please check me for errors.

Edit: Tom, your math would calculate what pressure a 5 ft tall pipe would give: about 2.17 PSI. I hope that helps you to see where you were making a mistake.

I agree but for clarification 1 US gallon is 231 cubic inches so 10836/231 is 46.9 US gallons.
an imperial gallon is 277.42 cubic inches so 39 imperial gallons as stated.

and of course I'm not sure which parts of this are relevant to the original post but at least I understand now.

[Capuchin]

I agree but for clarification 1 US gallon is 231 cubic inches so 10836/231 is 46.9 US gallons.
an imperial gallon is 277.42 cubic inches so 39 imperial gallons as stated.

and of course I'm not sure which parts of this are relevant to the original post but at least I understand now.

Thanks, I'm british, So I don't really know much about US gallons :)

[speedball1]

OK OK... I put the wrong 56gal... but it is still 11.55 ft. Tom, your math would calculate what pressure a 5 ft tall pipe would give: about 2.17 PSI. I hope that helps you to see where you were making a mistake.

I sure do. I worked it out the long way and came up with the same answer. Eleven and a half feet will, indeed, give you 5 PSI. It seemed so simple doing it my way but I've been doing the math wrong for years and you all have my apologies for that. You don't know how very hard I try to be accurate and when I fail, (like now) it reflects on the entire page. Again, my sincere apologies for any harm my stupidness may have caused and from now on I promise to keep my hands off the math.
Regards to all. Tom

[rick4747]

Holy volume "BATMAN". Who would have thought such an innocent question would have stirred such a debate!