pressure loss with lake irrigation system

when my system starts up the pressure is great. after 10-15 minutes the pressure starts to drop of at the sprinkler heads. the system is about 11 years old. i have cleaned the strainer on the end of the intake line and checked for any air leaks in that line and found no problems. do you have any suggestions?

terry

You might have small pressure tank in line with your lake irrigation system which would explain the timed pressurized water. If so you can tweak the pressure switch so it kicks back on at a higher pressure.

I've had a situation where a pump still runs but once taken appart it became apparent that the propeller was missing blades reducing it's efficiency.

pressure loss

if the impellors were worn or damaged wouldn't the pressure be reduced immediately?

Can you give us some info on your pump and system. We're shooting in the dark here.

bob...

pressure loss

2hp centrifugal pump w/ 200' intake line pumping to 12' elevation above water level. serving 4 zones w/ a manual zone changer. water level is down about 5 1/2 feet from normal. end of intake line is in about 12" of water.

So your lifting the water 17.5' through 200 feet of what kind of pipe? And if it's Poly or PVC, what pressure rating does it have?

Twenty five feet is maximum lift for any centrifugal pump and 200 feet of a pipe that may be too small could cause a lot of friction loss. Since your lifting 5.5' more than you were, this could be the reason your system is operating at the lower pressure. Maybe you were on the verge of having low pressure before the lake level dropped.

bob...