PSI from 1 HP 4" Submersible Well Pump

Any idea on what the PSI would be from a 4" submersible well pump (SFS Pro Series)? Manufactured by F.E. Myers
1 HP, 230 Volts, 20 GPM, 9.8 Amps, SF= 1.40, PH=1
Cat No.: 2SFS102-20
The Well is approx. 90 Feet
The Motor is a Franklin Electric Model: 2445089003

I need to change out ( install larger irrigation head nozzles) or double up on the zones since installing the well. It's blowing out some water from the pressure relief valve.

I'm trying to calculate nozzle GPM flow and I don't know the PSI the pump puts out
Thanks for you help
Rich

psi

Put a gauge in the line somewhere. There is no way to calculate the pressure since it varies depending on the operating water level in the well, the volume of water being used, pipe size and length, etc. Unless the pump is oversized, the larger the nozzles used, the lower the psi will be.

I sell Myers and am not familiar with a SFS Pro. But a Rustler 1hp 20 gallon per minute will make a maximum head of 255 feet. That converted to pressure would be 110lbs. This is assuming the water level is zero feet. For every foot you go down you will lose .433 lbs. of pressure.

So like HJ said, it depends on the water level.

Is sounds like you have the switch set pretty high if the pump is cycling and the pressure relief valve is blowing too.

bob...

OK...thanks for the reply.
The drillers came out today and and put on a new pressure relief valve after I told them I doubled up on the zones. They said it's sometime common for the valve not to reseat itself all the way once it blows. The valve reads "Set Press 75 PSI...Max Press 200 PSI."
In the 1" PVC outlet line coming out of the pump, I installed a threaded 'T' with a plug to blow out the system in the fall. If I put a gage in there, do you think it would give me a fairly accurate reading?

They said the reason it blew in the first place is because of the 5 heads on 1 zone is only putting out ~2.5-3 GPM X 5 heads = 13-15 GPM which is less than the 20 GPM the pump puts out...That's the reason I'm trying to find the PSI. Hunter gives you a chart that shows the approx. GPM and radius for different PSI ratings...I'm just not sure if it's 30, 40, 50 or even 60 PSI.

I'm guessing that I would want to stay around 20 GPM ( or slightly above) per zone.?

Thanks

Sure, it will read system pressure minus friction loss when water is running which shouldn't be too much.


bob...

You should find the operating point for the pump. The 1 HP 20 GPM pump curve at the link below is probably pretty close to your pump. They may change the model number but they can't do much to change the pumping physics.

http://www.femyers.com/pdf/pdf.ws/ws%20brochure/k3143-60.pdf

Forty PSI is probably enough for a sprinkler. That is 92.4 ft of head.

Your well is 90 ft deep but let's estimate 60 ft to water. Now the total is 152.4 ft.

20 GPM in 1 1/4" pipe has 6.4 ft of loss per 100 ft. Let's say 13 ft for 200 ft of pipe. Total now is 165 ft.

The 20 GPM Myers pump at the link pumps 20 GPM at 165 ft of head.

So if your nozzles discharge 2.5 GPM at 40 psi, you might try 8 nozzles.

The flow rate at the nozzle is proportional to the square root of the pressure, so increasing the pressure from 40 to 50 psi will give you about 12% more flow per nozzle.

You can easily find the operating point by testing. Put a gauge and a valve to discharge off your main line. Run the pump and close down the valve until your existing sprinklers are spraying with the range that you want. Now measure the discharge from the valve with a bucket and a watch to determine the GPM of excess flow. Figure out how many new heads you need to use that flow.

Cookie, you are reading the possible pumps that could be in that particular box. You have to figure out if it is a two or three wire and if it is a 1/2, 3/4, 1 or 1.5 hp pump. Then the liquid end could be anywhere from 5 to 25 gallons per minute. It is most likely 10 gpm, since that seems to be what the big box stores sell.

bob...

This is a hard to answer question. I have discovered that both Goulds and Myers seem to low rate their pumps. There are many other pumps as well that are built by the same company that build these pumps. I know of both a Goulds 1 hp pump at 250' depth that exceed these pressures, and a Myers 1hp at 300' that will exceed this pressure