Water Hammer
Have you ever felt vibrations and heard noise underneath your feet when shutting down your lawn sprinkler system? This is what is known as "water hammer". Water hammer is what happens when moving water is suddenly stopped.
When the valve shuts down, the water hits up against the inside of the valve and it sends shock waves through the pipe. These shock waves go back and forth to opposite ends of the pipe. If water hammer is too violent, it can cause fittings and joints to become loose.
So, how is water hammer controlled? Well, as an irrigation system designer we want to keep the flow of the water in the pipe under 5 feet per second. We do this by using our pipe friction loss charts and noting our gallon per minuet limits through a certain size pipe that we are using.
For example, in 1" thin wall PVC we don't want to push over 16 gallons per minuet thorough the pipe. Staying at or below this will ensure that the water doesn't exceed 5 feet per second. Trying to push more than this amount will result in excess water hammer and excess pressure loss due to friction.
If you are designing an irrigation system, make sure that you know what you know the limits for the particular pipe you are using. If in doubt, use the pipe friction loss chart to determine how much water you can safely push through the pipe. These charts can be found in irrigation books or inside irrigation part catalogs.
Scott Young
http://www.autolawnsprinklers.com
When the valve shuts down, the water hits up against the inside of the valve and it sends shock waves through the pipe. These shock waves go back and forth to opposite ends of the pipe. If water hammer is too violent, it can cause fittings and joints to become loose.
So, how is water hammer controlled? Well, as an irrigation system designer we want to keep the flow of the water in the pipe under 5 feet per second. We do this by using our pipe friction loss charts and noting our gallon per minuet limits through a certain size pipe that we are using.
For example, in 1" thin wall PVC we don't want to push over 16 gallons per minuet thorough the pipe. Staying at or below this will ensure that the water doesn't exceed 5 feet per second. Trying to push more than this amount will result in excess water hammer and excess pressure loss due to friction.
If you are designing an irrigation system, make sure that you know what you know the limits for the particular pipe you are using. If in doubt, use the pipe friction loss chart to determine how much water you can safely push through the pipe. These charts can be found in irrigation books or inside irrigation part catalogs.
Scott Young
http://www.autolawnsprinklers.com
posted by Irrigationman at
7:37 PM
1 Comments:
I think I have this problem. When my sprinklers turn on, it sounds like a violent explosion has occurred under my house. The previous owner ran pvc to the sprinklers in the backyard and when they come on the entire house shakes violently. Any ideas?
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