Flow thru holes drilled CPVC pipe

[kimsan]

I have a 2" CPVC Pipe with 30psi water at ambient, I would like the pipe to sprinkle the water in various directions by drilling small holes in the pipe (1/8 - 3/8" dia?). Is there a relatively easy method to determine how many of what size hole would give me a certain capacity of flow.

Any help would be appreciated. Thanks

 

[jte]

kimsan-

Have you considered going to a hardware store, spending $15 on a 2" pvc end cap, pipe, 2" x 3/4" reducer, a 3/4" pipe and 3/4" garden hose thread connector, and building a mock-up in your backyard? It may not be a textbook approach, but it's guaranteed to work. You'll have to control your household water pressure (usually 40 to 80 psi) or make some adjustments to your results to bring them down to 30 psi.

jt

 

[mstrobscure]

Obtain a reference for the design of septic systems and look at the section on pressure dose piping. A good reference is the EPA design manual for onsite septic systems.

Alternatively, you can calculate the flow out of each hole as follows:

Q = Cd * A * SQRT(2*g*h)

where:

Q = cubic feet per second (CFS= gpm/448.8)
Cd = coefficient of discharge (normally used is 0.61)
A = area of hole in square feet
g = gravity 32.2 ft/sec^2
h = head of water in ft (ft = psi*2.31)

The problem is if you have multiple holes along the length of the pipe, the flow rate will vary along the length of the pipe as a function of how much water and pressure are in the pipe. Normally, you want to limit the headloss in the pipe to 10% or less of headloss across the hole for relatively equal distribution.

Hope that helps.