Your water capacitor is a bladder tank, or pressure tank. It is
normally a metal tank with a rubber bladder in it with a fitting on one
end for the water and the other for air to pressurize the bladder.
Small ones are very common in new houses to help reduce the damage from
water hammer, large ones are used on wells so the pump does not have to
run all of the time. You should be able to find some at your local home
improvement stores in the section that has the pumps.

Kim





Pszemol wrote:
"Boomer" wrote in message
...

I do not know what you mean by cycle. A booster pump should keep a
constant pressure on the RO membrane. Cycling would be self-defeating,
for if the pressure changes, do to a on-off phase, there would be a
continuous pressure difference on the membrane.

Or are you talking about a RO container pressure pump, that keeps made
RO water in a container at x pressure to pump to y place.


OK, more details...
I have got Aquatec DDP5800, what they call "a demand/delivery pump".
Hooked it up to my KENT 10gpd barebone RO system and turned the pump on.
There was a pressure gauge in between the pump and the prefilters...

When the pump was cycling on and off on the limit switch I saw the gauge
going from the 40PSI (my tap water static pressure) to 65-70 PSI the moment
the pump was on. 1/4, maybe 1/8 of the second later the pump turned off
itself on
the pressure switch and the pressure started decreasing to the 40PSI
when the
pump turned itself on again... This cycling seem to be due to the fact
the pump
had large capacity and pumped pressure high up really quick reaching the
limit.
The water did not have the way to escape through the RO filter that
quickly so
the pump turned off. When the pressure relatively slowly dropped back to
the
40PSI the pump turned itself back again...

I almost feel like I need a "water capacitor", using kind of electrical
analogy...
Some flexible device/container which could take the pressure from the pump
and release it over time feeding the need for water of the RO filter...
Or a much
smaller capacity pump which will just barely keep up with RO filter demand.