Ball Valve Function Classification
1, by-pass valve, ball valve, generally for hydrostatic open, so set a by-pass valve flat first, that is filled with water on both sides;
2, air valve, water filling, exclude air taking buoy to close the valve; Drainage, supply air with, float to fall;
3, the pressure relief valve: open shutoff valve, eliminate between valve and plug the pressure of the water, so as not to wear sealing cover;
4, drain valve, discharge a sewage at the bottom of the ball inside the shell.