I have acquired a new compressor rated at 540 L/min @ 7 bar 150L tank I decided to test this at 23 degC, timing compression at 2 bar intervals (0-2, 2-4 etc.) I was surprised to find that it maintained 34 seconds at each interval up to 8 bar (but this could be poor experimental controls)......(300L/34)*60 = 529.4 L/min I thought... that's pretty good, we don't know the exact size of the tank..... so I guess it is a true 540 L/min. However, the @ 7 bar seems redundant, because there was no apparent change. I set up a spreadsheet to understand different compression rates at different temperatures, but I may have failed. --------------------- V1 = normal liters per minute = V1 = (P2/P1*T1/T2)*V2 V2 = liters per minute = V1/(P2/P1*T1/T2)*V2 T1 = temperature at normal conditions = 273.15K T2 = actual temperature of air = T1 + air temp in Celcius P1 = pressure at normal conditions = 101.325 kPa P2 = actual pressure = say 7 bar = 709.275 or 810.6 Kpa (not sure - I chose 810.6kPa) if V2 = 540 ....&.... T2 = 273.15 (0C) V1 = 4320 NL/min I thought.... knowing V1 @ 273.15K I could then find V2 @ 23 degC But V2 = 585.47 L/min V2 should less than 540 L/min I then ran if V2 = 540 ....&.... T2 = 296.15 (23C) V1 = 3984 NL/min (V1 @ 0C) - (V1 @ 23C) = 336 NL/min There is 336 NL/min less @ 23 deg C. This made sense. Using V1 = 336 NL/min @ 23 C = 46 L/min Therefore the compressor pumps 46L/min less at 23 degrees C as compared to pumping at 0 degrees C Here's the spreadsheet: https://drive.google.com/file/d/0B9HHPLN8L5Mxel9YU0oyNTIzZ2M/view?usp=sharing ------------------- I don't know if a manometer read @ 7 bar should be calculated at 7 or 8 bar. But more than that... I just don't know whether this maths is correct or not. Can anybody confirm or deny this?