I have acquired a new compressor rated at 540 L/min @ 7 bar 150L tank(adsbygoogle = window.adsbygoogle || []).push({});

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.

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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

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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?

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# Calc L/min air compression to different pressures & temps in my compressor

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