Product specifications

RO Membrane
Reverse osmosis is a scientifi c method of reversing nature’s biological process where a dilute or lighter
solution passes through a semi-permeable membrane into a more concentrated solution. In the human
body fl uids pass in and out of such membranes (cell tissues) by the phenomenon known as osmosis
while plants absorb food and moisture from the soil in the same way. Scientists have long realized if
the natural process of osmosis could be reversed—if water from concentrated sources could be made
to pass through a selective membrane and emerge as pure water, many practical applications could be
developed. For instance, unwanted salts and other dissolved inorganic minerals could be removed from
all kinds of water sources. The process was originally perfected by NASA and DOW Chemical to purify
and re-use all liquids aboard spacecraft. Reverse osmosis fi lters out all particles greater than .0001 mi-
crons in diameter.
The membrane used in your PWS™ BEV-300 system is a privately manufactured, custom rolled, spiral
wound polyamide thin-fi lm-composite membrane. This membrane has the ability to remove in excess
of 97% of the dissolved inorganics. Rejection is based on degree of removal of sodium and chloride ions.
Although RO has a higher percentage of removal of all di, tri, and quadri-valenced elements (e.g. >99%
of aluminum) any mono-valenced elements are rejected at ~97% level. The nominal remaining 3% of
dissolved solids, mostly monovalent, enter the next stage of the process—the deionization module.
Deionization (DI) Module
Deionization resins are a man-made plastic bead chemically made anionic (OH
-
) and cationic (H
+
). The
resins in your PWS™ BEV-300 system are of nuclear grade and carefully matched to the reverse osmosis
membrane. (As opposed to commercial grade resins typically found in water softeners.) In the DI mod-
ule, H
+
and OH
-
are exchanged for the mono-valenced elements in the product water coming from the
RO membrane. The only thing added to the product water from your BEV-300 system is hydrogen ions
(H
+
) and hydroxyl (OH
-
) ions, which combine to form H
2
O, or pure water.
Following the DI resins are several additional inches of granular activated carbon. This is included to
insure the complete removal of any organic contaminant that might appear in trace form from a partial
degree of removal via RO and DI. Since we’ve never found any organics which are not removed either by
the upstream RO membrane or the DI resins, the GAC at this stage acts primarily to polish the product
water for a clean, fresh taste. GAC is the most common product used to fi lter bottled or “spring” waters.
Finally, the end of the DI module contains two additional stages which are in place as safeguards against
any reverse migration of contaminants.
Built-in Flush Valve
The built-in fl ush valve mounted to the RO pressure vessel provides a quick and simple method to peri-
odically fl ush the surface of the RO membrane. Simply opening the fl ush valve once every two weeks for
ten minutes will wash away impurities that may be concentrating near the surface of the RO membrane.
If not occasionally fl ushed from the membrane surface, impurities can concentrate and clog the pores of
the membrane. Flushing the membrane ensures longer service life and greater rejection of contaminates.
OPERATING PARAMETERS
To insure proper operation of your BEV system, it is advisable to collect the following information about
your water supply. This information is generally available from your municipal water department, and
in many cases is available online.
Pressure
In order to overcome the natural osmotic force, adequate water pressure must be available from your
water supply. The osmotic force is directly proportional to the concentration of dissolved solids in the
water. When the water pressure is equal to the osmotic force, there will be no movement of pure water
molecules across the semi-permeable membrane. A minimum of 40 PSI is recommended. (If your water
pressure is below 40 PSI, a booster pump is available. If you are on a private well, have your plumber
raise the minimum pressure above 40 PSI.)
Getting to Know Your BEV System 11