Well, it seems as if it was there, at least for opening. In the definition of partial model PartialValve, there is the parameter filteredOpening and riseTime, the last defined as the time to arrive to 99.6% opening. What I see is that this partial model is used only in the models ValveIncompressible, ValveVaporizing, and Valvecompressible, but not in ValveLinerar or ValveDiscrete. The ValveIncompressible model is used in the Examples.IncompressibleFluidNetwork, so perhaps you can check its action there. 

thanks that solves it