Cary,
thanks for all your help....
is there a standard depth to put a CSV in the well drop pipe?
The CSV125 is a non-adjustable valve. They come in 40,50, or 60 PSI. And the further down the well you install it, the less pressure it will deliver by 1 PSI for every 2.31 feet it is installed below the surface. So if you install a 60 PSI valve down the well 23' deep, it will only deliver 50 PSI.
You need to install the CSV 3 to 4 feet below the pitless adapter to be able to center it in the well. So if your pitless is 5' below surface and you set the CSV 3' below that, it will be 8' below surface and a 50 PSI valve will only deliver about 46 PSI.
The CSV12560-1 valves are designed to regulate about 4 PSI higher than 60 PSI, so you still get 60 PSI after setting the CSV below surface 8'. But the 50 and 40 PSI valves do not have the extra 4 PSI, so you want to set them as close to the surface as you can.