I agree that your 3 HP motor needs about 2 GPM for proper cooling. The pump curve also shows that 10 GPM, 3 HP pump to deliver 880’ or 380 PSI of backpressure. So to set the CSV1A at 50 PSI and not have more than 125 PSI differential pressure, the static water level needs to be at 473’ or deeper.
When the pump has to lift 473’ before the water gets to surface, you will lose 205 PSI of the 380 that pump can build. So the CSV will only see 175 PSI on the inlet, and with 50 PSI set as the outlet, there is only 125 PSI differential pressure. A shallower static water level of 415’, would cause a differential pressure across the CSV of 150 PSI, which is the most I would like to see across the valve. The higher the differential pressure across the CSV, the sooner it will wear out.
There are cases where a pump like this is set at 600’, with a static water level of 100’. These are usually weak producing wells, so the pump starts when the water level is at 100’ static, and pulls the water level down to 590’ as more water is used. In this case the backpressure on the CSV, and the pipe before the CSV, will be 338 PSI when the pump first starts and the static level is 100’.
To reduce 338 PSI to the 50 PSI you need, we would use two of the CSV1A valves in series. The first valve would see the 338 PSI and have a downstream setting of 190 PSI. The second valves would see the 190 PSI, and have a downstream setting of 50 PSI for the house. This way there is only about 140 PSI differential across either CSV, and they will last a long time.
The Cycle Stop Valves listed on our literature are the standard valves we use the most. However, we make specialty valves for different applications all the time. For instance the first valve in the above scenario would be a CSV1A with a 2 GPM minimum and a spring with an adjustment range of 150 PSI to 300 PSI. The second CSV1A would have the standard 15-150 PSI spring, but would also be made with a 2 GPM minimum. We can match a CSV to almost any pump or application.
With a 2 GPM minimum, you just need to make sure your drip system zones use 2+ GPM to keep the pump from cycling. Multiple tanks as you have are the best way to handle long term flow rates of less than 2 GPM. But be aware that flows less than 2 GPM will still cause cycling. If your tanks have 80 gallons of drawdown and you have a 1 GPM drip system, the tanks will be empty in 80 minutes. With maybe 5 minutes to refill the tanks, that would be a cycle every 85 minutes.
It will only take about 5 minutes to refill tanks with 80 gallons of drawdown, even though the CSV has a minimum of 2 GPM, because you set the CSV at 58 PSI while using a 40/60 pressure switch. In this way the tanks are almost full before the CSV starts working or limits the flow to 2 GPM.
