Pipe Flow Question 1

[Jeter316]

What is the best way to determine water pressure and flow through a line when all I know is the entering pressure? I have a 1" water line that I would like to take about 300ft up a hill and I' have my doubts as to whether or not I have enough pressure. I estimate the pressure on the existing 1in line to be ~45psi. The elevation difference is about 80ft. Thanks.

 

[BigInch]

Knowing nothing your best bet is to get a chart showing flowrates and pressure losses per each 100 feet length of a certain diameter (1" in your case) horizontal pipeline to help with friction losses and then add the extra pressure needed to lift it to your elevation. Don't forget to take the true length of your pipe up the side of the hill (horiz_run^2 + vertical_run^2)^0.5 to calculate friction losses. Extra pressure for lifting water to 300 ft elevation P_elev psi = 300ft * 62.4 pcf/144in2/ft2
is 130 psi. So now add 130 plus whatever these charts tell you.

FOR PVC PIPE

For a 10 gpm flow with 1" PVC pipe you'll lose 2.5 psi/100 foot length, so if its 1000 ft long, you lose 25 psi. So that would be at least a total of 325 psig needed at the pump discharge.

FOR COPPER TUBE

FOR STEEL PIPE
use a value about 1/2 way between copper tube and PVC.

"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward CEO BP
"Being GREEN isn't easy." Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.liv

 

[Jeter316]

Thanks for the feedback. I think I understand but let me make sure. I need to clarify a couple things first. The elevation difference is ~80ft to the top of the hill and the 300ft is the total length of pipe. The pipe will be PVC.

So you're saying I need to account for the static loss first, which in this case it's ~34.6psi for the 80ft to the top of the hill. If I only have ~45psi at the 1in pipe I'm connecting to, that means I will only have ~10.4psi of static pressure at the top of the hill?

If that's true, then for maximum flow at the pressure I have available, 10.4psi/300ft which equates to 3.5psi/100ft of friction loss which gives me ~10.25gpm max(from the chart) at the top of the hill for 1in pvc?

Thanks for the help.

 

[BigInch]

OK, I thought the hill was 300 ft high.

I prefer to think of it as 45 psig - 34.6 psi static = 10.5 psi of working head available at the source point, but numerically its the same thing as what you're saying.

It does looks like you can get 10.25 gpm at 80 ft elev.
And if you raised it to 104.4 feet elev., you'd get no flow at all, so don't go much higher than 80 ft, or you'll have a hard time filling a bucket.

"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward CEO BP
"Being GREEN isn't easy." Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.liv

 

[cvg]

this is all based on the pressure loss in Type K copper tubing. Your pvc pipe may be smoother and may also have a slightly different inside diameter. Both will affect the flow rate. You need to confirm the velocity and headloss using the correct diameter and roughness. Plus add in minor losses for any fittings.

 

[BigInch]

cvg, use the first chart.

"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward CEO BP
"Being GREEN isn't easy." Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.liv