View Full Version : Water flow question
samkent
10-September-2008, 05:16 PM
Scenario 2 pipes each 1 inch in diameter and 10 feet long being fed by a 1 inch garden hose at identical water pressure.
Pipe 1 straight and normal with the other end open.
Pipe 2 has the other end plugged but has ¼ inch holes spaced at 1 foot intervals. Total of 10 holes.
Would the volume of water delivered through pipe 1 be greater over a 1 hour period?
Would the volume of water in each of the 10 holes in pipe 2 be identical or would the last hole be lower?
Neverfly
10-September-2008, 05:29 PM
Scenario 2 pipes each 1 inch in diameter and 10 feet long being fed by a 1 inch garden hose at identical water pressure.
Pipe 1 straight and normal with the other end open.
Pipe 2 has the other end plugged but has ¼ inch holes spaced at 1 foot intervals. Total of 10 holes.
Would the volume of water delivered through pipe 1 be greater over a 1 hour period?
Would the volume of water in each of the 10 holes in pipe 2 be identical or would the last hole be lower?
Assuming 60-70 psi (since you said garden hose) Pipe 1 would exhibit greater flow with the holed end of pipe 2 acting as a Flow Restrictor.
The pressure will increase and the flow will decrease for pipe 2.
The water flow through the ten holes would be a bit variable with the bottom holes showing the greatest flow. Other moments, the middle holes may show greater. That's a bit of fluid mechanics and the differences will vary by pretty much slight amounts and I wouldn't consider it all that worth figuring out the statistics on it...
Just bear in mind that the pressure was raised in Pipe 2. Without the force of gravity, the holes would mostly be around identical with some variance.
NEOWatcher
10-September-2008, 06:13 PM
Nothing wrong that I can see with Neverfly's post, but it may be even simpler than that.
You would need 16 holes to equal the pipe opening.
So;even if pressure were the same at each hole (like maybe a sphere with all 10 holes at the end), you would have less flow.
Ok; now a bit more...
Add in the fact that pressure diminishes after each hole, and you've lowered the flow at each subsequent hole. This is why a sprinkler system get's progressively smaller after each head...It keeps the pressures more consistent.
There are formulas to determine the turbulance based on drag on the pipe walls, but it's been many moons since I've dealt with that topic.
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