How much water (gpm) is running through a 1/2 copper pipe at 65 psi?
In order to predict a flow speed, you need to know the pressure differential, In this case I'm going to assume you mean its 65 psi guage and that the water is flowing from the pipe at 65psig out into open air (0 psig). There are 2 basic equations at work here, the volumetric flow rate, and the pressure/speed relationship (Bernoulli's Principle). Assuming incompressible, inviscid flow (pretty applicable here) stagnation pressure must be preserved. P0P+1/2 *Density*Speed^2 So seeing as P0 can't change, you can make this P1+1/2*Density*Speed1^2P2+1/2*Density. We know speed 1 is zero, and P2 is zero so P11/2*Density*Speed^2 P1 65 psig 9360 psfg Density of Water1.94032033 slugs / (ft^3) Solving that equation with those values gives you 98.2 ft/sec The volumetric flow rate is velocity * area of the openning (in this case a circle with diameter 0.5 inches 3.14159*(0.5/24)^20.00136 ft^2 Volumetric flow rate is then 0.00136 ft^2*98.2 ft/sec 0.134 ft^3/sec which is 1.002 gallons per second. This is neglecting all types of friction in the pipe, and any vertical changes (or assuming that when you say 65 psi that its 65 psi right at the openning of the pipe). For relatively short distances the friction is negigible, and if you want to factor in the height the equation becomes P1+1/2*Density*Speed1^2 + Density*Acceleration of Gravity*Height1P2+1/2*Density*Speed2^2 + Density*Acceleration of Gravity*Height2
