Does a CSV valve have backflow? Updated after studying your site

[DIYguy]

Hello;
UPDATED: I spent more time reading and realized I want to ask different questions.
I deleted the old ones as they didn't make much sense in light of what I now understand you have....

 I was going to start by saying I have an unusual situation, but I  then read enough posts to realize the tremendous diversity of situations, and I won't claim to be unusual. I didn't see it covered elsewhere.

Anyway, I have a low-yield 25' well, at about 200 feet above sea level; i.e. usually 29.98 inHg barometric pressure.
It is about 300 feet away from my pump house, connected by a buried 2" Pvc pipe.
I have been using a 1HP Red Lion RJC-100 to pump it.
The 2inch PVC does *not* slope uniformly upwards to the pump, and thus it is a pain(!) to get primed.
There is a foot valve at the bottom of the suction line in the well.

The only way I can avoid overpumping the well (and sucking air, and losing prime) is to restrict the outflow to be up at 60psi. I have been trying to use a (old 1.5") pressure relief valve set at 60, but the setpoint is not very abrupt; i.e. not much difference between 60psi and 63 psi.
I'm still trying to get a good reading on the yield, but I think it is less than 1 GPM.

I also have a bubble trap I can vent , in piping above the jet pump output.
The other key to success is to have the pressure tank sitting at at least 50 PSI for startup;
this ensures the pump gets started without the dreaded 0PSI situation where there is no water in the jet.
Also, having the pressure tank helps make the jet pump more robust against entrained air;
when the pump gets an air bubble hiccup, the tank pressure pushes some water back into the jet pump and it burps and bounces around and then gets back to work. If i have gotten some air in the line, i  can carefully vent it without losing the jet venturi action.

(I haven't explored the lower bound of pressure tank PSI to ensure startup.
Admittedly, the pump stutters  badly initially until I vent some water and it settles down at ~75PSI, ramping down to 60 as the 2inch PVc transitions from +50psi to -10psi.
this is less than elegant... UPDATE; I realize I  need to just bypass the pressure switch on the RJC instead of trying to crank it up to 11ty...).
(At present, when I turn off the jet pump, the entire jet pump goes down to -10psi unless I allow it to suck water back in from the pressure tank).

Anyway, I'm trying to get this rig into a situation where it could operate unattended, and exploit the low-yield resource by filling up my 10K gallon redwood tank. (which presently leaks...)
I need a better PRV with a sharp cutoff, vs. gradual opening above the breakpoint.
It seems that you have this this behavior in the CSV, with the additional feature of the bypass flow.

My UPdated questions;
1. Where can I find data for flow vs. pressure when the CSV is shut, particularly in reverse pressure situations?
(somehow I am dubious that it is 1GPM regardless of differential pressure)
2. How do the smart people utilize the friction loss vs. flow rate data?
( i.e., CSV2  has ~7psi of friction loss at 0 GPM? I don't get that at all).
3. At this point I think I need a CSV (set at ~50Psi (or maybe PRV) to a pressure tank , which has a reverse check valve in parallel with the CSV to allow the suction line to recharge? and also on the pump output manifold, a PRV set to 60PSI which refills my big open tank. The idea of all of this is to insure the jet pump will restart, and then have it's output flowrate-limited to not overpump. (maybe I could add an input check valve, to minimize pressure cycling of my looooong  2inch PVC suction line. This goes against your generic advice of mutiple check valves in a single line.


Right now I have a 80 gal pressure tank, and I can overpump the well  (suck air, lose prime) just trying to get it filled up if it is empty and the well has not recovered any depth.

So, the remote shallow well that is only 25" deep is the source of many headaches.
I am hoping to find a way to keep my jet pump happy without needing an engineer to babysit it, and then use the ~1GPM to fill my big tank, which has it's own pump and hydrant network.

So, the  low yield shallow remote well  requires jet pump operating into a sharp PRV.
 The only way  I see to avoid overpumping is to sit up at the very high  pressure end of the pump curve, maybe 60pSI where zero flow pressure is 63 psi.
Thus, I am grasping at straws, to see if your fine CSV could help me out here.
(I don't seem to find any 1 GPM pumps that can pull from 25 feet down...)
 
So, whadayatink?
John
 I realize the 'reasonable' approach is to get power out to the well, and install one of your Cycle Sensors on a submersible.
Right now that is not feasible.

[DIYguy]

I just read the post from Dovecreek, and suddenly realized that 'Dole'  flow regulation 'valves'  might be very good for me,
at least on avoiding overpumping. Those valves seem like a constant current diode, where the PRV seems more like a zener, or maybe a PNP with the zener from base to ground.

I'll still be looking for a way to maintain some minimum pressure in the jet pump after I shut it down, regardless of whatever else can happen. I'm increasingly of a mind to put another checkvalve at the jet pump input, even though it will foil my ability to prime the suction line through the priming port of the jet pump. I run the risk of sucking outside air into the loooong suction line, but I don't like cycling it from -10psi to ~ +40  either. The other good thing about the input check valve is I can install a 'float valve' to vent any air bubbles automatically, without it operating in reverse...

I guess I need a traditional PRV, somewhere in the 30-50 PSI range,   on the output manifold, with a Dole valve after that. The PRV is to not allow the tank fill to drain out the (jet support) pressure tank after the pump is stopped , while the Dole valve would prevent  the tank fill process from overpumping the well.j
,
Similarly, I think I might need a Dole valve between the pump and the (Jet Support) pressure tank, maybe with a reversed direction check valve in parallel, to allow rapid recharge of the jet  as needed for hiccups, while avoiding overpumping the well to fill the (Jet Support) pressure tank at startup.

This whole system is just to fill my storage tank, which is probably where a CSV would be useful to minimize pressure variation from cut-in to cut-out of the distribution pump.
Thanks for your patience with this challenging situation.
John

[Cary Austin]

If the only check is the foot valve in the well, the pressure tank should keep the pump and 2" suction pipe pressurized while the pump is off.

If you put a 1 GPM Dole valve between the pump and pressure tank, the pump should not be able to pump a 1 GPM well dry.  And the Cycle Sensor will still work on the jet pump to shut it down if the well does get pumped dry.

[DIYguy]

Cary,
thanks for the advice. I'm still wondering about the best way to keep the (jet support) pressure tank pressurized when the pump shuts off. I think it would just drain out into the big holding tank . I've been using a hose bib I crack open during pumping and close before I shut down manually. I guess a solenoid valve would work, but it seems kludgey. Can I just use a PRV for this?
John

[Cary Austin]

A pressure relief valve is not very good at filling a storage tank and keeping a pressure from emptying.  I would use a solenoid valve with a float switch in the storage tank.  Then as long as the only check valve on the pump is in the suction line or even better a foot valve at the bottom of the suction line, the pump should stay primed.

[DIYguy]

thanks, I'll get the stuff and try it out, and let you know if I need more ideas.
John