HI Guys: I'm lookin for help specially from those who have been in industry. I'm trying to size valves for simulation purpose only,i.e. I'm notgoing to install the valve, just sizing them to match well with the whole model part of the concerned process. Following the sizing procedure that is available in the literature;I got the following: The flow cofficient of the water control valve is 58. Then if the selected valve is globe valve from fisher design ED of classes 300 with linear characteristics, then the size of the valve will be 2-inch. FoLLOWING THe same procedure for oil and gas phases I got the following sizes: 4-inch for oil and gas. Unfortunately I couldn't find on the fisher cataloque the time constant or response time of these valves. it is very essential in my simulation to include the dynamics of the control valves. So I'm kindly requesting from anyone who has experience with control valves to help me in the following: 1- what is the typical time constant for control valve? 2- The suitable time constants for the control valves with sizes mentioned above? thanx and waiting for help as soon as possible. regards assad.