What took more time to figured out is the system pressure. Ignoring
friction loss it should recover about 93% of the energy put in but the feed
pumps they use can only get to about 35-40PSI so I figure the system
pressure is around 600PSI. That is enough to produce some fresh water but
it is not enough to run the membrane at the nominal 12% recovery rate at
800PSI. Ran 600PSI through a SW30-2520 on my Filmtec simulator software and
come out with a 6% recovery which is about the displacement of the pump.
OTOH, gallons per amp hour is what counts so I guess driving the membranes

The Shurflo pumps they use are set to about 100 PSI. THus they do get
the ~800 PSI needed for decent efficieny.


at a low rate is a non-issue. You just have to get used to the constant
clump-clump of the pump for hours on end.

Ever hear a PUR Powersurvivor? They are not as quiet as the Clark
pumps by about 10 dB!


Evan Gatehouse