If an open, unchecked water pipe was being used to cool a machining process, the excessive volume of liquid being used would be obvious to see as it pooled on the floor. It would be clear that you would want to test lower flow rates that would conserve water and save money yet still effectively cool the part.

If an open compressed air line was being used to perform the same process, it would be much more difficult to envision the large volume of compressed air that could be wasted while trying to cool the same part.
Since compressed air generation is every bit as important to most factories as a supply of water, it only makes sense to consider ways to conserve it and reduce its expense.

Register and download the white paper, "Compressed Air Open Blowing," to learn the options available for reducing compressed air waste while still delivering the desired performance.

http://www.exair.com/caob190em.htm