How can I track down hydraulic data for valves? 1

[tstanton]

Can anyone offer ideas on tracking down Cv or K values for valves in a water distribution system? I am supporting an effort to create a real time operating system which requires head loss data for valves in the system. Unfortunately the client does not have good records of submittals made by the contractors furnishing the valves over the last 50+ years. In addition some valves were made by companies no longer in business or foreign companies that are difficult to contact and communicate with. Any suggestions would be appreciated.

 

[ccor]

Do the best you can with standard data from hydraulic texts. If the system is that old and variable the assumptions you make on the minor losses will not come close to having the effect of the assumptions you will have to make for pipe roughnesses. If an accurate model is needed a water audit and calibration should be performed, making the assumptions on minor losses more unimportant.

 

[stanier]

Crane, Idelchik and Miller have all published books on head loss coefficients through valves. If the valve bidies are 50 years old the as published data may not be relevant in any event. If it is that important to you then a test program of test ppints either side of a valve with a portable ultrasonic flow meter. You will find that the change to surface roghness and diameterof the pipe will dwarf any head loss across any valve.

 

[rconner]

...of course unless the old valve is inadvertently closed or severely throttled (might be good to check actual direction of openeing work and the valve before you test)!!