Bumpyroad wrote:
Harvey51 wrote:
What prevents water from lying in the lower half of a pipe while the air goes by in the top half? .
nothing
bumpy
High velocity air flow is what is needed to clear water from the horizontal (and vertical) sections of piping. A low velocity/low flow rate of air will clear some of the water, then just flow on by in the top half of the pipe. A high velocity/high flow rate will move more water along due to friction with the water surface and will break the water into droplets that can be carried vertically up to a sink faucet, etc. Obtaining the highest possible air flow through a piping section is the reason for blowing only one faucet at a time.
Successfully blowing out a piping system requires an air compressor capable of providing the necessary high volume of air continuously for a long enough time to get all the water out. Folks who report success in blowing lines must be owners of an adequate air compressor.