Quote: My previous estimate had been that it should require 10 horsepower or less. Have I missed something?
Yup, your calculations are extremely simplistic. You don't take into account the flow. What you think is taking into account the flow is just taking the volume of air every second seperately, and compressing it to 5psig and then moving on to the next volume of air, and compressing it. You are not actually taking the account the continual flow. Imagine if you will you have your ordinary shop compressor that is controlled by a variable speed (and hence power) compressor. The tank connected to it is a given volume (the actual # doesn't really matter). Now, say you have the tank pressurized to 5 psig, and you open the outlet valve just a little bit, and the compressor turns on to regulate things inside to 5 psig. Say the pump turns using just enough power to continuously maintain that 5psig. It won't take much power to keep the pressure up while the leak is small. Now, double the size of the leak, how much more power is required? A lot more. Ok, then try opening up the leak to 50% of the end area of the storage tank, now you are talking supercharger like pressurized flow. Your calcs don't even assume there is a small leak, just that it keeps filling up new tanks every second . . . The actual calculations are far from trivial, and far more than I even want to be reminded of this late at night (I hated fluids . . .)
