Draining a Backflow Prevention Device Assembly
When draining an assembly to prevent freezing, several important points must be remembered. The assembly cannot be adequately drained through the test cocks and drain valves must be added on the inlet and outlet sides of the assembly, below the assembly preferably below the freeze line if the remainder of the system is to be drained.
Ball valves should be drained for the winter in areas where freezing temperatures may occur. Open the ball valve approximately 45 degrees while draining the pipeline and assembly to allow water between the ball and valve body to drain. Leave the ball valve in this position for the winter to prevent freeze damage. Water will become trapped between the ball and valve body if the valve is left in either the full open or full closed position. If water should freeze between the ball and valve body, damage to the ball valve will occur.
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