Could provide an example of converting Nl/min to l/min.
Nl/min means "normal liters per minute". It is the amount of air that flows through a pipe, but calculated back to 'normal' conditions.
Normal conditions being:
0 degrees Celsius
1 atmosphere (1.01325 bar)
The quick and dirty method:
Divide the Normal liters per minute (Nl/min) by the pressure plus 1 to get the l/min through the pipe.
50 Nl/min at 7 bar = 50/8 = 6.25 l/min compressed air flow through the pipe.
The exact method, using the 'ideal gas law':
Since the amount of molecules stay the same, we can say:
V1 = (P2/P1*T1/T2)*V2.
V1 = normal liters per minute
V2 = liters per minute
P1 = pressure at normal conditions
P2 = actual pressure
T1 = temperature at normal conditions
T2 = actual temperature of air
The P1/P2 part compensates for the difference in pressure.
The T1/T2 part compensates for the difference in temperature.
In the calculation to normal conditions, we need to use absolute pressure (not relative) and absolute temperature (Degrees Kelvin: 0 degrees Celsius is 273.15 degrees Kelvin).
Example 1: 50 l/min at 7 bar, 25 degrees Celsius, to Nl/min
50 Lpm x (810 kPa/101.325 kPa) x 273.15 / (273.15 + 25) = 367 NL/min
Example 2: 500 Nl/min to actual compressed air flow at 7 bar and 20 degrees Celsius.
(7 bar relative = 8 bar absolute = 8 * 101.325 = 810 kPa)
500 Nl/min = (810 kPa/101.325 kPa) x 273.15/(273.15 + 20) * V2
We can calculate that V2 = 67.2 l/min
Answer: there flows 67.2 liters of compressed air thruogh the pipe, at 7 bar and 20 degrees Celsius.
liters/min is what you will measure using a flow meter. There are flow meters that can also show Nl/min (it wil need a built-in pressure and temp sensor also for this).
Nl/min is what is usually indicated on compressors and also on pneumatic devices.
I hope all of this made sense, it can become quite messy when typing math in plain text.
Why do you want to convert nl/min to l/min?
1) If you want know the correct pipe size for your compressed air system, be sure to check out my compressed air pipe sizing page.
2) If you want to buy a compressor en want to know the capacity? Go to the air compressor buying guide.
Please let me know if you have more questions.
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