# check valves

• posted
Anyone know if there a well tried and tested relationship for ball check
valves between ball diameter, hole diameter and ball lift restriction?
Alan
• posted
Hi Alan
I don't know what the ball diameter should be, but I would think 1.5 x the seat hole diameter would be ok.
It strikes me that the area of the hole diameter D and radius R is: Pi x R x R and the area of port opened by ball lift of L is Pi x D x L
We would want these to be equal or perhaps the lift to be slightly greater for max flow.
Pi is on both sides and D = 2 x R
so the Hole area, R squared = the lift area, which is 2R x L
R x R = 2R x L
divide both sides by 2R
L = R squared / 2R
substituting D for 2R
L = R squared /
D
Anyone have any better thoughts?
Steve (Sheffield)
• posted
This any help?
I'm thinking you can link litres/sec at X overpressure to ball lift.....
Michael
• posted
In message , Steve writes
I have just looked at a couple of published designs of boiler back-head clacks (LBSC & Don Young) who seem to favour a ball:seat ratio nearer to 5:4. As Steve has already pointed out, minimum lift depends upon that ratio.
Whether ball movement is free or closure is spring assisted, it would seem obvious that to ensure fast and clean action the range of movement of the ball in any direction must not be much greater than the minimum required for free flow. Thus in addition to constricting the lift, the diameter of the horizontal space in which the ball is lifting is also important.
• posted
Steve You have done all the work but I think you can continue and say L= R squared /2R and cancel out the R's to L= R/2 or D/4 which gives the lift to equal the hole dia. Alan
• posted
this is what i built for waste oil burner pump
this is one of them outlet...the ones on the inlet are built slightly reversed
sorry cant take the pump apart for pics as its in use ...
the top half threads into the lower half.
o-ring fitted to the little plunger that seats on the chamfer at the end of the drilling ..
not much restriction in this design
the guide on the plunger is x-section ...so you get good flow ..
squiggly thing is spring.
not quite to scale ...and drawn quickly