[Control Valve] Calculation of the valve resistance ratio

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I would like to ask the experts on this forum about the calculation of the valve resistance ratio S for control valves: For ordinary control valves, the valve resistance ratio S is typically set between 0.3 and 0.5, based on engineering experience. My question is whether, when calculating the total pressure drop across an entire piping system, this total pressure drop includes the pressure difference resulting from the height difference between the inlet and outlet of the system In my case, the pressure at the water extraction point at the pump outlet is P1; the pressure drop in the pipes (including fittings) is △P_Line; the pressure drop reserved for the valve is △P_Valve; the pressure at the container inlet is P2. The height difference between the pump outlet and the container inlet is 17 meters (with the container located above). In this case, which of the following two formulas for calculating S is correct? 1) S = △P_Valve / (△P_Valve + △P_Line + △P_H17m) 2) S = △P_Valve / (△P_Valve + △P_Line) It seems that this issue of pressure differences isn’t mentioned in any of the available materials; therefore, I would like to ask the members of this forum how they take this into account in actual calculations Thank you~~ flowers~~