Ball-type Check Valve resistance coefficient (K)
Ball-type Check Valve resistance coefficient (K)
(OP)
Having an impossible time tracking down a resistance coefficient for a 2" ball-type check valve. Can anyone help me out?
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Ball-type Check Valve resistance coefficient (K)
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RE: Ball-type Check Valve resistance coefficient (K)
K=2.3 (From Crane Technical Paper #410)
K=0.5 (From Boston Soc. Civil Engrs. V42#3,pp.263- 286,1955)
Idelchik,I.E. etal,1986,"Handbook of Hydraulic Resistance",2nd Ed., pg. 429 gives the following formula for a spherical valve with a spherical seat within 0.125<h/D<0.4
Lambda=K=2.7-(0.8/(h/D))+(0.14/(h/D)^2)
D is the valve diameter and h is the valve opening distance not defined for a spherical seat in a spherical valve.
RE: Ball-type Check Valve resistance coefficient (K)
RE: Ball-type Check Valve resistance coefficient (K)
The L/D for a ball check valve is 150
For each pipe diameter, D4, D3, D2, D1 (exit to entry)
Calculate the fluid velocity,
V = Q / A
Calculate the Reynolds number,
If mixture then, Re = ?mixVD / ?mix
If vehicle then, Re = ?vehVD / ?mix
If liquid then, Re = ?liqVD / ?mix
Calculate the Fanning friction factor, ƒ
If Calc method = Newtonian mixture, vehicle, liquid then,
If Re < 2100 then, ƒ = 16 / Re
If Re > 3000 then, ƒ = 0.0625 / (LOG(k / 3.7D + 5.74 / Re0.9))2
If Re > 2100 and Re < 3000 then, interpolate
If Calc method = other procedure then,
Calculate ƒ using the selected procedure (eg Lazarus & Neilson)
Calculate the head loss in metres of mixture,
?Hpipe = (4ƒL/D)V2 / 2g and ?Hfittings = KV2 / 2g
Calculate the pipe wall pressure drop,
If mixture then, ?Ppipe = ?mix g ?Hpipe
If vehicle then, ?Ppipe = ?veh g ?Hpipe
If liquid then, ?Ppipe = ?liq g ?Hpipe
Calculate the fittings pressure drop, ?Pfittings = ?mix g ?Hfittings
Have fun
RE: Ball-type Check Valve resistance coefficient (K)
K = Darcy's f * Leq(ft) / D(ft)
Leq. = 19.0 for a 2" swing check.
I've probably been no help, but...
RE: Ball-type Check Valve resistance coefficient (K)
K =~ 891*(d^4)/(Cv^2) ... with "d" in inches
Using the Edward-supplied Cv value of 51.5, and an ID of 2.067 (2" SCH 40), I came up with 6.1323. Given that similar to various lift check K values, it'll do.
Thanks for all the advice! Itdepends, your reply was very informative, though a little more involved that I need. Thankfully, I'm not designing a system. I'm just trying to determine if we need some piping or pump modifications to better balance one of our sump pump systems.
RE: Ball-type Check Valve resistance coefficient (K)
Iha, very insightfull. For complete turbulance (rough pipes) f = 0.019 for 2 inch sch 40, therefore, K = 2.9 for the ball check and 2.5 for conventional swing check, your number.
My newer Crane TP 410 (1978) lists K = 100 * ft for a swing check with ft = turbulent friction factor for 2 inch pipe = 0.019 so K = 1.9. For 50 gpm, L/D = K/f = 1.9/0.023 = 83 diameters. It omits the in-line ball check valve.
gibsi1, IMO, k = 6.1 seems a little high for a ball check.
It is interesting to note Crane (1969) suggests a minimum pressure drop across the ball check valve of 0.25 psid (horizontal) and 2.5 psid (vertical) to fully lift the ball.
Donald Blachly, PE
RE: Ball-type Check Valve resistance coefficient (K)
RE: Ball-type Check Valve resistance coefficient (K)
I found Cv of 107 and 130 so there is a lot of variation.
But your Cv is from your manufacturer.
Where did you find the relationship of Cv to K?
Donald Blachly, PE
RE: Ball-type Check Valve resistance coefficient (K)
RE: Ball-type Check Valve resistance coefficient (K)
Good luck,
Latexman
RE: Ball-type Check Valve resistance coefficient (K)
RE: Ball-type Check Valve resistance coefficient (K)
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This books lists a ball check at a Kl of 4.5
RE: Ball-type Check Valve resistance coefficient (K)
4.3 feet (or almost 2 psi) at 2 fps;
27.2 (12 psi) at 5 fps and
108.7 ft (47 psi) at 10 fps.
You would need a booster pump at each valve!
Further, the k of a 3/4 closed gate valve is 24, so a ball check would be almost 3 times as restrictive as a 3/4 closed gate valve. I've always used gate valves for isolation; I should start using ball check valves ;-0 Just a little weekend humour.
I am fairly certain k is nowhere near 70 for a ball check.
The Chinese ideogram for “crisis” is comprised of the characters for “danger” and “opportunity.”
RE: Ball-type Check Valve resistance coefficient (K)