Pressure drop

[frankcar1965]

I'm thinking about a CSV and am wondering how much pressure drop across the valve.  I assume I would be using the CSV1, I would like 60psi if possible. I also wonder about the back pressure on the piping.  I only use the well for yard irrigation and have very good pressure now, I use Gilmour X-Large impulse sprinklers which for optimum distance require 60psi but since I usually run two at a time I don't quite get full throw but amazingly pretty close. I actually can run three with not too much loss in distance, certainly better than most sprinklers, these really put out the water.  However, sometime I need to run only one or maybe small uses and that, of course, makes the pump cycle which I want to avoid. 
The well pump is: Grizzly 75C21112G12, the well is 160ft deep, static water is 20ft, pump at 130. Pressure tank is 20gal.

The well man that came to set everything up did not do a pump down test which I really wanted but said I had more water than I would ever use and he was right. I have pumped for 6 hours at full 12gpm and it never ran dry even during "exceptional" drought we had this year. It is an old well drilled in 1960 which surprises me, no iron or sulfur, very good water. It just gets colder and colder the longer I use it.  Which valve would I use and how much pressure drop would there be. Thanks Frank

[Cary Austin]

At 15 GPM the CSV1 has less than 2 PSI friction loss.  If you are getting 12 GPM at 60 PSI with that pump, the water level must be close to 80’.  So the backpressure from that pump will only be about 120 PSI when you using 1 GPM.

[frankcar1965]

Thanks, what do you mean "close to 80' " the static was at 20'. I have a 60/40 pressure switch so I mean the max could be 60psi, the pump does not cycle when using two sprinklers. I'm not understanding what you mean.

[Cary Austin]

If your static level is 20', then the backpressure from that pump will be 145 PSI.  I was assuming a pumping level if 80' because that pump shows to be able to produce 12 GPM at 60 PSI from a depth of 80'.

[frankcar1965]

Ok, I think I know what you mean.  That pressure loss is fairly insignificant btw, I thought it would have been more. So the CSV1 is the one I would need? This is a new pump so I want it to last as long as they can, nowadays anyway. The only trouble I will have is that the well guy did not leave me much room, things are pretty tight, and then the electrician also did not leave me much wire length, I'll have to work everything in as best as I can.

[Cary Austin]

Even our CSV1A valve would only have about 8 PSI loss at 12 GPM.  It might be a better fit for installing in a well house or utility room, and it is adjustable if you need to make changes.