Hey everyone. Four days ago I didn't know anything about fluids but I started my internship and got assigned a project that is all about fluids! And I need some help, this topic can get really complicated but I'm trying to take it one step at a time. Problem Description: There is a pump attached to a tank (really it's two pumps and two tanks but lets keep it simple). The pump can produce 34.5 psi at about 4 gal/min flow rate, and I need to determine the pressure drop at the end of the system. The pipe network is complex, or at least I think so. It is probably 200 feet in total with plenty of bends, elevation changes, fittings(valves and whatnot), hubs where pipes branch off, and so on. My Solution: I was going to take the system one piece at a time, calculate the pressure drop after each piece, and then use that as my initial pressure for the next piece working my way around. I am going to do this in Excel so I can keep track of the pressure throughout the system. To get a rough estimate I was first going to look at all the bends, straight pieces, and elevation changes and then start adding more details. To do this I am using the Darcy-Weisbach equation but I'm not sure this is correct because my values are coming out wrong when I test it. I'm using this currently: P1 +rho/2(v1-v2)-[(rho*v2^2)/2]*(f*L/D+kb)-(z2-z1)*rho*g = P2 P1 - initial pressure P2 - final pressure Rho - density v1 - initial velocity v2 - final velocity f - friction coefficient D = inner pipe diameter z1/z2 - heights I think one of my problems may be with units, I have a ton of variables in Excel so I do need to straighten that out. But also one of my main concerns is that right now I am using 4 gal/min as my flow rate, and using that to calculate velocity, Reynold's number, and the friction coefficient. But shouldn't flow rate be a variable also? Otherwise the velocity will never change. I know in theory the flow rate and velocity are constant, but wouldn't they be changing in a system with friction? If anyone can give me some guidance on this topic I would be really appreciative. I really want to make sure I do a good job with this internship and would love any help I can get. Thanks in advance and let me know what questions you may have for me!