No problem-just a question

What would be the maximum pressure a 1.5 hp submersible pump such as a "Gould 7GS15" put out under optimum conditions? "400 feet deep in well
water level 15 feet from surface. Just curious.

One of the well guys will be able to give you your answer but I would like to know why your well is 400' deep with the water 15' from the surface. It doesn't make much sense to me unless the water table has changed since the well was drilled or you require massive ammounts of water.

WE didn't get any volume until 400 feet.

WoW, Out where I am a deep well with good flow is 100' or so. Most people hit water anywhere from 15-70'. I don't know of any wells over 150'. We have 1 town that all you have to do is dig with a shovel to get water. Many in that town have geo thermal cooling.

Of course at that pressure you would have zero flow, so what is the real question? The pressure and flow will vary, because if you didn't get good volume of water until you reached the 400' level, then the pump will have to pump against a varying head, i.e. it will start only having to pump from the 15' level, and after it empties the water column down to the 380' level where you may have hit a water bering level, now it is pumping against about 150psi more.

Rancher

A Goulds 7GS15 delivers 2 GPM at 660 ft of head, 4 GPM at 625, 6GPM at 555, 8 GPM at 460, and 10 GPM at 330 ft.

A 7GS20 delivers 6 GPM at 760 ft, 8 GPM at 640 ft, and 10 GPM at 480 ft.

I would pick the 7GS20 for that application or the 5GS15. The 5GS15 will give you 5 GPM at 660 ft of head and the 7GS20 will give you 7 GPM with 705 ft of head.

Starting at 660 ft of head from the pump at 5 GPM, allow 40 ft of head loss for friction and 160 ft for 70 psi at delivery, and you have only 460 ft remaining for lift. The 5GS15 goes to 800 ft of head at 3 GPM and 735 ft at 4GPM so you have a lot of head margin if you can accept 3 or 4 GPM.

The 7GS20 gives you 705 ft at 7 GPM and 850 ft at 4 GPM if you need that much water and the well will produce it.

If you want to stay with 1.5 HP you should select the 5GPM pump. If you need more flow, go to the 7GS20.

Either will work with 1" pipe.

I failed to catch the part about 15 ft from the surface and used the 400 ft as depth to water.

If the water remains near the surface you need a different pump.

Please clarify the depth to water and pumpdown and I will update the posting.

The most important question is: How much water will this well produce?

bob...

You wouldn't set the pump on the bottom of a 400' deep well. And pressure isn't how you size a pump, if that's the reason for the question. The pressure desired at the highest fixture is part of the equation though.

I would use that pump if it fits the peak demand gpm and pressure the building requires. In reality, the head starts at the water level in the well to the highest fixture plus pressure loss in the pipe/fittings.

This may help;
http://www.irrigationtutorials.com/pump.htm

Are we talking a rock bore or fully cased and screened well? I ask because you'd set the pump at different depths depending on the type of well. In a rock bore, if you want to plan ahead for drought and lower static water levels, you'd size it for setting it at 385-390' (capable of pumping water from just above that depth).

If you have a 6" well, you have 1.47 gal/foot of water above the pump's inlet; so 385-15=370 * 1.47=544 gallons of water PLUS the recovery rate gpm of the well. Screened wells usually have the pump set in relation to the highest producing section of screening.

Or you can set the pump in either type well at 15-20' above the pumping level of the well. Pumping level being where the water level remains constant and 10-20' above he pump.

If you use PE pipe in a roll, you will have the least pressure loss of all choices of drop pipe, and only two fittings from the pump to the top of the well and another two to three to the pressure tank.

Pump

It is not a case of what the pump will put out, but what kind of pump you need. If the dynamic water level is 350' then you need a pump that will develop 155 psi to get water to the surface, then an additional 50+ psi to pressurize the system. Once you find pumps that have that performance capability, then you have to choose the one that develops the gpm you need. The flow chart for your Goulds pump will give its capacity parameters.

Sorry for not being clear. This is the situation.
My neighbor already has this pump in his well set at 400 feet. Well is all rock with a 6 inch steel casing at top. Most wells in this area are 400 to 500 feet deep to get any volume, yet water will rise to top and at times overflow.
The pump puts out about 12 gpm at 40-60 psi and the pressure tank holds 10 to 12 gallons.
He wants to put a cycle stop valve under the pitless adaptor So the pump won't cycle as much. I was worried the pressure would be to high between when the csv closed [with a 1 gpm flow to fill pressure tank] and the pressure switch cuts out.
INfo on csv says pressure differential across valve cannot be more then 125 psi. csv model CSV1W.

285 Psi!!!

The 7GS15 delivers 2 GPM at 660 ft of head. That is about 285 psi.

The differential of 285 - 60 = 225 is 100 psi more than the valve is rated to withstand.

That illustrates one of the reasons I don't like CSVs on high-head submersible pumps.