We Replace Submersible Pumps
We just got done replacing another submersible pump. This pump was inside a 4" PVC well and was a 3hp (horse power) 50 gpm (gallons per minuet) pump that was hanging on 1&1/4" schedule 80 PVC drop pipe. This pump's power source was supplied with standard residential 1 phase power, not commercial 3 phase electrical which I have worked with on occasion.
Every 20 feet was an 1&1/4" galvanized threaded coupling. The well was approximately 360' feet and the pump was hanging 160' feet down in the well. The water table was approximately 60 feet. I would have used at least 1&1/2" or 2" PVC schedule 80 pipe instead of the 1&1/4" pipe. We got just under 40 gallons per minute from the pump at open discharge. The reason for this is because of the distance to water and the size of the drop pipe.
If the water table was higher, the 3hp 50 gpm pump would deliver more (or a higher volume of) water. Also, the drop pipe is restricting the volume and thus pressure. To top this all off, the irrigation system was over-sized. What I mean by this is that most of the zones were demanding too much water or more water than the pump could keep up with.
There are a couple of possible solutions to this problem. The 160' feet of 1&1/4" drop pipe can be replaced with 2" schedule 80, or all the zones demanding too many gallons per minute can be lowered by changing nozzles and/or sprinkler heads. For example, there is one particular zone with twelve 3.0 (three gallons per minute per head) that demanding about 36 gpms . By changing just half of the nozzles to 2.0's, I can lower the demand of this zone by 6 gallons per minute.
Of course, you want to try and achieve matched precipitation, but in practice it is difficult to get it exact and imitate mother nature's precise even watering. So, you want to do your best to design, layout, and build a sprinkler system that will water as evenly and efficiently as possible. Some irrigation contractors can do this better than others...
The system also operated with a pressure tank, specifically a bladder or diaphragm tank and uses a 30/50 psi pressure switch. We also installed a new pressure tank which came pre-charged with air. I lowered the psi in the tank to 28psi before installing and filling it with water. So, the system actually operates on a 28/48 psi cut-on and cut-off range.
Submersible pumps are powerful because the push directly rather than having to create a vacuum or suction like a centrifugal pump, or use hydraulics to force water to the surface like a jet pump. Replacing your submersible pump can be easy or hard depending on your knowledge, skill, tools, and strength. If you have never replaced a sub-pump, I do not recommend doing it. You should only do it if you have had replaced these types of pumps with an experienced person with you to help teach you.
Scott
http://www.autolawnsprinklers.com
Every 20 feet was an 1&1/4" galvanized threaded coupling. The well was approximately 360' feet and the pump was hanging 160' feet down in the well. The water table was approximately 60 feet. I would have used at least 1&1/2" or 2" PVC schedule 80 pipe instead of the 1&1/4" pipe. We got just under 40 gallons per minute from the pump at open discharge. The reason for this is because of the distance to water and the size of the drop pipe.
If the water table was higher, the 3hp 50 gpm pump would deliver more (or a higher volume of) water. Also, the drop pipe is restricting the volume and thus pressure. To top this all off, the irrigation system was over-sized. What I mean by this is that most of the zones were demanding too much water or more water than the pump could keep up with.
There are a couple of possible solutions to this problem. The 160' feet of 1&1/4" drop pipe can be replaced with 2" schedule 80, or all the zones demanding too many gallons per minute can be lowered by changing nozzles and/or sprinkler heads. For example, there is one particular zone with twelve 3.0 (three gallons per minute per head) that demanding about 36 gpms . By changing just half of the nozzles to 2.0's, I can lower the demand of this zone by 6 gallons per minute.
Of course, you want to try and achieve matched precipitation, but in practice it is difficult to get it exact and imitate mother nature's precise even watering. So, you want to do your best to design, layout, and build a sprinkler system that will water as evenly and efficiently as possible. Some irrigation contractors can do this better than others...
The system also operated with a pressure tank, specifically a bladder or diaphragm tank and uses a 30/50 psi pressure switch. We also installed a new pressure tank which came pre-charged with air. I lowered the psi in the tank to 28psi before installing and filling it with water. So, the system actually operates on a 28/48 psi cut-on and cut-off range.
Submersible pumps are powerful because the push directly rather than having to create a vacuum or suction like a centrifugal pump, or use hydraulics to force water to the surface like a jet pump. Replacing your submersible pump can be easy or hard depending on your knowledge, skill, tools, and strength. If you have never replaced a sub-pump, I do not recommend doing it. You should only do it if you have had replaced these types of pumps with an experienced person with you to help teach you.
Scott
http://www.autolawnsprinklers.com
posted by Irrigationman at
8:52 PM
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