I am looking for a formula to let me obtain a pressure reading comparison for two different tests based upon the following information: I have a given flow rate in liters / minute. (same for each test) I know the size of the orifice that the water is flowing through. (same for each test) My question is the following. Would there be a pressure difference between the two tests due to the location of the testing laboratory. One lab is very high above sea level (I can get the exact information) and the other lab is almost at sea level. I realize that this is probably a very ignorant question, but I am a biologist trying to fit into a physicists world.