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-   -   I have a Franklin submersible pump model 12 GS05412 that has reduced output (http://www.diychatroom.com/f18/i-have-franklin-submersible-pump-model-12-gs05412-has-reduced-output-150562/)

brandtlarr 07-17-2012 08:04 AM

I have a Franklin submersible pump model 12 GS05412 that has reduced output
 
The pump is about 10 years old and has worked fine. This year I don't have enough pressure to operate the impact lawn sprinklers as before. I thought this was due to the drought we are in and caused by a low water table. I could hand water and get approx 2-5 gal per min. the pump is about 30 feet deep from the surface.
The ohmic value of the wiring is as follows: green to black, red and yellow-infinity. black to yellow 5 ohms, red to yellow 18.5 ohms, black to red 22.5 ohms.
I pulled the pump and does not appear to have anything, trash or etc., plugged on the unit that would result in reduced flow.
When I pulled the unit the water table is up almost high enough to drain into the shallow 8 foot pit where the electrical is. So this is not the problem of low water table. i don't believe there are any leaks in the water lines.

J. V. 07-17-2012 10:30 AM

Check the impeller and make sure its tight on the shaft. Also, the impeller could be worn. If the motor runs without tripping a breaker or overload, it is not the electric motor. It is a mechanical issue.

Yoyizit 07-17-2012 02:19 PM

As the water level above the pump drops, the pump GPM drops because the PSI input to the pump drops.

You could check power draw.
For a 100% efficient pump/motor, HP = GPM x feet of Head/3956. Most Grainger pumps seem to be between 20% and 80% efficient. Small pond pumps come in at 10% or less.

curiousB 07-17-2012 03:54 PM

Quote:

Originally Posted by Yoyizit (Post 968052)
As the water level above the pump drops, the pump GPM drops because the PSI input to the pump drops.


?!?!! Yeah but no...


GPM is determined principally by static head. That is the vertical height from the well water level to the point it is being lifted to. The amount of lift from the pump impeller to the top of the well water is "free" and doesn't impact your GPH.

Yoyizit 07-17-2012 05:11 PM

Quote:

Originally Posted by curiousB (Post 968108)
?!?!! Yeah but no...


GPM is determined principally by static head. That is the vertical height from the well water level to the point it is being lifted to. The amount of lift from the pump impeller to the top of the well water is "free" and doesn't impact your GPH.

Try it. . .like I did. And reread what I posted. :whistling2:

micromind 07-17-2012 07:57 PM

The resistance measurements posted are about right for a 1/2 HP motor operating at 230 volts.

How many capacitors does the control box have? If it's one, the motor is very likely ok. If there are two, it's possible that the run capacitor has gone bad. This will result in lower RPM and thus, lower pressure and flow.

The sure-fire way to know if the motor is performing as it should is to check current while it's running.

For a 1/2 HP 230 volt motor with one capacitor, the current should be around 5 amps on Y and B; 0 amps on red.

If it's two capacitors, the current should be about 4 amps on Y and B, and about 2 on red.

If the current readings are normal, the problem is not the motor.

Rob


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