| Reverse
Osmosis Technical Center |
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What
is Reverse Osmosis
Reverse
Osmosis, also known as
Hyper-filtration by the industry, represents state-of-the-art in
water treatment technology. Reverse Osmosis (RO) was developed in
the late 1950's under U.S. Government funding, as a method of desalinating
sea water. Today,
reverse osmosis has earned its name as the most convenient and thorough
method to filter water. It is used by most water bottling plants,
and by many industries that require ultra-refined water in manufacturing.
Now this advanced technology is available to homes and offices for
drinking water filtration.
How
It Works In
short, it is the process by which water molecules are forced through a 0.0001
micron semi-permeable membrane by water pressure. Long
sheets of the membrane are ingeniously sandwiched together and rolled up around
a hollow central tube in a spiral fashion. This rolled-up configuration is commonly
referred to as a spiral wound membrane or module. They are available in different
sizes for processing different quantities of water. Typically, a module for home
water treatment is as small as 2" diameter and 10" long, while one for industrial
use may be 4" diameter and 40" long.
For the membrane
to be usable it must be in some type of container (membrane housing) so
pressure can be maintained on its surface. It is this pressure that supplies
the energy to force the water through the membrane, separating it from
unwanted substances. The most amazing aspect of RO is that the substances
left behind are automatically diverted to a waste drain so they don't
build up in the system as with conventional filtering devices. This is
accomplished by using a part of the unprocessed water (feed water) to
carry away the rejected substances to the drain, thus keeping the membrane
clean. This is the reason to why RO membranes can last so long and perform
like new with minimum maintenance even after years of operation.

Higher
Performance RO membranes Begin With Shorter Leaves
The
heart of a reverse osmosis system is, of course, its membrane. Yet not
all membranes are made the same. Different manufacturers fabricate their
membranes differently. For example, spiral-wound membranes are comprised
of membrane "leaves" individual sheets of membrane through which
feed water passes and is filtered. Some membrane brands have fewer and
larger leaves. Some have more and shorter leaves. Short-leaf design costs
more to fabricate, but is advantageous because less pressure is required
to deliver water to the end of each leaf, and more uniform flux is maintained
from one end of the leaf to the other. The result is a highly efficient
membrane one that provides safer drinking
water and a longer life. For example, APEC's high quality water
is achieved by advanced reverse osmosis membranes which have up to twice
as many leaves and each leaf is 1/3 to 2/3 shorter than those in other
membranes. Besides the overall system design and the quality of parts
used, the membrane is the reason why different ROs have different rejection
capabilities.
Flow
Rate of Reverse Osmosis Systems All
reverse osmosis systems are rated (and priced) by their flow rates (Gallons of
Product Water Produces Per Day). The effectiveness and productivity of RO systems
increase with greater water pressure and temperature. The actual flow rate (in
GPD) of any reverse osmosis system depends on your home water pressure and temperature.
This is why all of our systems are named as they are, for example: 36/45 GPD means
it is rated at 36 GPD at 50 psi of water pressure, 45 GPD at 60 psi. While the
industry standard* is set at 60 psi, we know that not everyone's cold water is
at 60 psi and 77 degrees F. Instead of misleading customers into thinking that
a 45 GPD system will guarantee a flow rate of 45 GPD, we remind you that you might
get less than 45 GPD —perhaps 36 GPD or even less if your pressure and temperature
are very low! So when flow rate is critical for you, you need to consider all
these factors. *Please
note that the industry standard is not necessarily followed by all vendors. We
have seen other RO systems claiming 100 GPD at 100 psi very unrealistic
input water pressure! So do check on these facts before you make a buying decision.

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