- Question Title: inadequate air supply
- Asked by: Guest
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- Answers: 1
We recently purchased a machine that requires 450litres of air per minute. We have a compressor (Atlas Copco GA30) that produces 4,800 litres per minute.
what we noticed is that the machine keeps shutting down and gives an error of insufficient air flow.
what could be the reason for this?
Answers & Replies
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Hi,
It's important to check unit in which the air consumption is expressed.
In 'compressed air land' we have two units which are often used.:
- l/m (liters per minute)
- Nl/min (normal liters per minute)
Nl/min is the output l/min (at 7 bar for example), calculated back to normal conditions (about 20 degrees, 1025mbar). Which is basically the same as the amount of air that the compressor is sucking in, not which it is pushing out.
Now there is often a lot of confusion about the use of these units and what they exactly mean. Don't even trust the compressor salesman, or the pneumatic equipment salesman, often even they don't know exactly the difference!
Best to explain it with an example: say a compressor sucks in 700 liters/min of ambient air. The air is compressed to 7 bar (compressed 7 times smaller) and at the output we measure (about) 100 liters/min.
This compressor has an output of 100 liters/min at 7 bar. But in the world of compressed air, we like to say 700 Nl/min. Often you will see sometghing like this: 700 l/min FAD, which means FREE AIR DELIVERY.
See this page here for more info on l/min and nl/min.
Now to answer your question:
Look at page 14 of this PDF(link to Atlas Copco, you see the FAD of your GA30 for different models of GA30.
Since you indicate you have 4800 l/min output (which is FAD in Normal liters per minute). I assume you have a GA30 10 bar version.
Your machines uses 450 l/min. But there is no indication if this is Normal liters per minute or liters per minute at a certain pressure.
If it is 450 l/min, at 10 bar it is actually 4500 Normal liters per minute!!! And this is pretty close to the 4800 that your compressor can supply. Actually, it probably won't be able to supply the 4800 l/min as this is measured in optimal laboratory conditions.
So, check the units. What type of machine is this? Small, big?
If it is a small machine and needs only 450 Nl/min, than look at the size of the piping/hosing that connects to your new machine. It might be too small? Are there maybe filters or other obstructions installed? Try to measure the pressure at the machine, when you run it. Does it drop significantly?
Hope this was enough information. If you need more help, let me know.