I have a vapor system that requires a 50 psi feed of DI water. Without getting fancy, is there a simple commercial off-the-shelf part I can buy, fill with water and hand-pressurize? Or something with an NPT inlet & outlet that I could pressurize with nitrogen or some other inert gas? At maximum, I think I'd need a 10 gallon reservoir - something that can sit on a lab bench.

The alternative is to slap a small pump in the reservoir, but that seems like overkill.

  • $\begingroup$ What is "COTS"? $\endgroup$ – Solar Mike Feb 4 '18 at 9:01
  • 2
    $\begingroup$ Just a WAG, but I suspect it means "Commercial Off The Shelf" $\endgroup$ – fred_dot_u Feb 4 '18 at 11:21
  • $\begingroup$ Obie trice... !! $\endgroup$ – Solar Mike Feb 4 '18 at 11:49
  • $\begingroup$ Yep, it's commercial off the shelf. I un-acronymized it. $\endgroup$ – phyllis diller Feb 4 '18 at 21:29
  • $\begingroup$ Do you have vertical room? Most likely completely impractible for a lab, but a tank 1384 inches high will get this pressure head. convertunits.com/from/Water+Column/to/psi $\endgroup$ – Carl Witthoft Feb 5 '18 at 18:22

A well storage pressure tank may serve your purpose. There are reverse osmosis tanks that are designed to handle up to 100 psi (per Amazon item post) and ordinary well tanks with internal bladders that provide at least your specified 50 psi.

Bladder tanks will be larger than the water capacity, as half the volume contains a rubber bladder. Air pressure fills the bladder, pressurizing the water as the well pump fills the water volume portion. When the pump reaches cut-off pressure, the bladder is compressed and maintains that pressure as the water is drawn off.

Without a bladder tank, as your tank empties, the pressure would drop.

If you will be hand-pressurizing the tank, you are the cut-off switch and can adjust via air-pressure gauge on the air pump or fill nozzle of the bladder.

A quick search discovered bladder well storage tanks as small as 2 gallon, 4 gallon, and 14 gallon which makes it more likely one will find a 10 gallon capacity.


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