Keep Compressed Air Dry!
It is vital to keep compressed air dry. Most compressed air systems have liquid water and water vapor, as a consequence of the compression of ambient air. Even if the atmospheric air at the compressor intake is only at 15% relative humidity, by the time the air is compressed to 100 psig (compression rate of 7.8), the compressed air is 100% saturated. Any cooling of the compressed air will allow liquid water to condense in the air lines downstream of the compressor. Liquid water can freeze at the worst possible time. Water vapor can’t be filtered out, but can be removed by efficient air dryers, especially during winter months when temperatures dip below freezing. If you experience water in your air lines, drain the water from the low spots in your piping, filter bowls, and check those “automatic” drains to make sure they are working properly.