Have you ever felt vibrations and heard loud noise under your feet when shutting down your lawn sprinkler system? This is known as ” water hammer” in the plumbing & irrigation industry. This is caused when moving water is suddenly stopped.
When the valve shuts down, the water hits up against the inside of the valve, & it sends shock waves through the pipe. These shock waves go back and forth to opposite ends of the pipe. If the water hammer is to violent, it may cause the joints and fittings to become loose and leak.
So, how do you control water hammer? When the sprinkler system is designed, you want to keep the flow of water in the piping at approximately under 5 ft per second. This may be accomplished by using pipe friction loss charts and noting the GPM (gallons per minute) limits through the size pipe being used (usually 3/4 – 1″ for residential).
As an example, if 1″ thin wall PVC pipe, you don’t want to push over 16 GPM through the pipe. Stay at or below the 16 GPM as this will help in not exceeding the 5 ft per second. By trying to push more water through the pipe, the result will end up producing water hammer as well as loss of pressure due to friction.
It is always beneficial to have any repair or installation work for your lawn sprinkler system performed by a Licensed Irrigation Contractor such as the professionals at Elite, as these certified technicians have the knowledge and experience to avoid this issue.