K Value for Wafer Check Valve?

[polyroly]

I am doing some hydraulics and I can't seem to find the k value for a wafer style check valve anywhere. Anyone know where to find it or have an approximation that they use? I also need the k value for a duck billed check but I am not sure that there is a k value out there.

Thanks in advance,
Nathan

 

[gerhardl]

Will vary according to construction and exact size and dimensions. Find a decent supplier, they will publish on homepage or tell you direct.

 

[stanier]

Cv, Kv and zeta values are available from

http://www.noreva.de

for their non slam wafer check valves.

If your waterhammer analysis determines that you dont need this sophistication then try the Tyco Water website.

Geoffrey D Stone FIMechE C.Eng;FIEAust CP Eng

http://www.waterhammer.bigblog.com.au

 

[vzeos]

Most manufacturers of flow components can provide you with the component capacity in terms of a Cv value from wich you can calculate the K value from K=891*d^4/(Cv^2) (see Crane page 3.4).

 

[rcooper]

Be a little careful, the K value varies as the two half disks open up, so it is high for low velocities and decreases as the velocity increases. For the velocities I tend to use in water, the K value tends to come out around 2.5

 

[katmar]

I'm with gerhardl on this one. There are many different types of wafer check valves and it is essential to get the specific data for your valve from the manufacturer.

Katmar Software
Engineering & Risk Analysis Software

http://katmarsoftware.com

 

[SteveWag]

Crispin and Val-Matic have a solid disk, spring loaded check with values in their Catalogs. I always use these 16-inch and below, they don't cost much and they will not slam. I have replaced other valves with these and always solved the problem. The duck billed check can be a problem, as I have found the published info to be far from field conditions, mostly with Red Valve Co. out of Pittsburgh.

Steve Wagner