Friction Loss in Half Open Gate Valve

[Chance17]

How should someone model the friction loss in a half open gate valve using Crane 410 methods?
This is embedded in a PE examination question.

 

[georgeverghese]

If a generic profile for Cv vs valve opening is not available in the referenced edition of Crane, then would say this question is impossible to answer in the context of an exam, unless the question also says to assume a linear profile ??

 

[rconner]

While I agree the exam question is (at least based on just what is posted here)technically not well or fully qualified for rigorous answer, is it possible the framer of the exam question simply wanted the head loss calculated, or calculation procedure explained, e.g. working from a head loss coefficient published in some edition e.g.

https://books.google.com/books?id=z...age&q=crane 410 half open gate valve&f=false?