Use Automatic Drain Valves to Prevent Sprinkler System from Freezing. ... But the actual sprinkler lines are usually shallower and have to penetrate the surface, where the soil is typically colder. An automatic drain valve in these lines can help by draining the water down and out of the pipes before it can freeze.
Some compressed air auto drains work on the float principal. As water and contamination accumulates in the bottom of the bowl, it will ultimately lift a float. The compressed air, under pressure in the bowl, will then vent to atmosphere through the drain opening, blowing the water and debris from the bowl as it does.
A valve used to drain off material that has separated from a fluid or gas stream, or one used to empty a process line, vessel, or storage tank.