piston pump?

Question

d=(2A-a)m*n*s/231 therefore i know my flow rate its 2.9gpm butt what s the formula for the speed of piston?is this true v=lenght of stroke*rpm or v=lenght of piston rod*rpm and what should be the diameter of my cam? pleas egove the formula or give me the the relavant web site

Answer 1

For a single-acting (one delivery stroke/revolution) single-cylinder piston pump, the volume rate in gpm = pump displacement in in^3 * rpm / 231 in^3.
Pump displacement = 0.25 * pi * bore^2 * stroke (where pi = 3.14159).
Average piston velocity v = 2 * stroke * rpm as the first answer states.
The cam/crank throw should be 1/2 * stroke. I assume the diameter you refer to is twice the throw, or equal to stroke.

Answer 2

2.9 gpm, your average flow rate, is equal to stroke volume times strokes per minute. Since you know the piston area, this gives you stroke length. Stroke length times strokes per minute, times 2 (remember, you need the other 1/2 cycle to fill the volume) gives you a length/minute which is the RMS value of the instantaneous speed at the piston pin, which will vary according to cam shape and relative rod length.