Question
QUESTION: I just installed a new 2hp sprinkler pump that draws water from a 1000gal water tank to sprinkle my lawn.  The thing works great when turned on.  My issue is when I turn the pump off there seems to be so much built up pressure that the connection I have that goes from the water tanks to the pump (foot valve attached to end of intake pipe) basically explodes and water just shoots out all over the place.  I've used different compression fittings (2" intake pipe) to easily take the pipe off if needed but they all fail.  My last resort is to make a permanent connection (pvc glue).  Did i put this thing together wrong or is it normal to have this built up pressure there?

ANSWER: I am having trouble understanding why there is so much pressure on the suction side of your system, but it is obvious that you have a problem.  I think it might be water hammer that is the culprit.  When water is moving in one direction and abruptly stops, it creates a pressure surge that will damage the system.  There are several remedies, but I have never heard of it occurring on the suction side.  Check out this link for a little reference and some ideas on solutions.

http://www.irrigationtutorials.com/waterhammer.htm

---------- FOLLOW-UP ----------

QUESTION: Hello again.  Fist off I wanted to say thank you for the quick reply.  Prior to installing my sprinkler, I went through the irrigationtutorials.com website many times.  I looked at the water hammer stuff along with the remedies but cam to the same conclusion as you...why the pressure on the intake?  As a follow up, since the problem still exists, I had hoped you mite be able to walk me through what is happening when I use my sprinkler pump.  First I wanted to lay out my system and then maybe you mite be able to help through understanding.  My setup = I use water tanks as my source.  I then have an intake tube 2" leading to my sprinkler pump.  The tube has a foot valve at the end. the top of my sprinkler pump is set up with a T on the output side of the pump with a cap in order to have access to prime the pump when needed. this leads to a valve manifold with 3 valves.  I used 1" valves and pipe for my entire system.  following the valves I have these little drain plugs and then some check valves to prevent water from flowing back towards the valves.  My pump/valves/tank all sit at probably the lowest point of my yard so when the sprinklers turn off the water will naturaly flow towards the pump/valves.  For test purposes I have the pump set on a simple on/off switch and I operate the valves via the bleed screw. logically speaking, is there any reason for there to be this stored pressure when I turn the pump off and if so why and how might I relieve this?  Thanks again for the help.  If you can think of anything that might help me understand the workings of the system I'd greatly appreciate it.  Thanks

Answer
I'm baffled by your situation.  I just cant reconcile the pressure situation on the suction side.  Maybe a defective foot valve?  I just don't know.  I have asked a few of my colleagues about it and they are just as perplexed.  I am sorry that I cant come up with something more sound for you.