The C_V for a valve determines the flow through the valve when it is fully open. The flow characteristics express how the flow changes between zero and maximum as the valve is stroked between fully closed and fully open. Neither can be inferred from the other. Look to the valve manufacturer to provide both. The C_V is always important, but for block valve applications the flow characteristics are usually not. The exceptions are very fast processes and/or valves (such as large motor-driven valves) with long stroke times.

Mr. Smith, what delta P considered for you when determining Cv for a specific valve? I think that delta P is the most important constant in Cv determination and that resulting flow their consequence. If it's not true, pls tell us why. Rgds, Jomar Duarte Filho - CONE/CondEsp.