Having an impossible time tracking down a resistance coefficient for a 2" ball-type check valve. Can anyone help me out?

Blevins,R.D., 1983, "Applied Fluid Dynamics Handbook",Van Nostrand Rheinhold gives in Table 6-10, case 9 for a ball check valve
     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.

I found a correlation between K and Cv. The manufacturer listed Cv on their website, but not 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.

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