Horizon Reverse Osmosis Seafari Versatile Series, Owner'S Manual

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Seafari Versatile 450 - 1800
Page 1-4
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1.8 GLOSSARY
Following terms are helpful in becoming familiar
with the HRO System.
BOUNDARY LAYER / CONCENTRATION POLARIZATION
When water permeates through the membrane,
nearly all the salt is left behind in the brine
channel. In any dynamic hydraulic system, the
fluid adjacent to the wall of the vessel is moving
relatively slow. Even though the main body of the
stream is turbulent, a thin film adjacent to the wall
(membrane) is laminar. This thin film is called the
boundary layer.
At the boundary layer the salts are saturated
and can readily adhere to and pack into the R.O.
membrane element surface if the Feed Water Flow
is insufficient. For this reason it is important to
maintain sufficient Feed Water flow, to prevent
Concentration Polarization, through the R.O.
membrane element.
BRINE VELOCITY
The brine flow over the membrane surface is
very important to both product water quality and
quantity. At low flows, concentration polarization
occurs, causing the water quality to decline.
In addition to inferior product water quality,
low brine flows can increase the precipitation
of sparingly soluble salts which will foul the
R.O. membrane element surface (concentration
polarization). If this occurs, the product water flux
(production) will decline.
The Feed Pump integrated design provide a
relatively smooth and continual flow of Feed Water
across and through the R.O. membrane element.
COMPACTION
Some densification of the membrane structure may
take place while operating at elevated pressures,
above 1000 PSI. The change is known as compaction
and is accompanied by a reduction in the water
permeation rate.
When the Reverse Osmosis membrane element is
subjected to elevated pressures beyond 1000 PSI the
Product Water Channel becomes squeezed which
results in restriction and in turn product water
recovery reduction.
OSMOTIC PRESSURE
The transfer of the water from one side of the
membrane to the other will continue until the
head (pressure) is great enough to prevent any
net transfer of the solvent (water) to the more
concentrated (feed water) solution.
At equilibrium, the quantity of water passing in
either direction is equal, and the head pressure
is then defined as the “Osmotic Pressure” of the
solution having that particular concentration of
dissolved solids.
PRESSURE
The operating pressure has a direct affect on product
water quality and quantity. Both factors will increase
as the system pressure increases (higher quantity
and higher quality within design limits).
The system must be operated at the lowest pressure
required to achieve the designed product water flow
rate. This parameter also minimizes compaction,
which proceeds at a faster rate at higher pressures as
well as at higher temperatures.
The System self adjusts its operating pressure to
maintain a precise amount of Product Water Flow.
However in so doing, at low temperatures and
or high salinity feed water conditions the system
will operate at higher than normal pressure in
maintaining the specified amount of product water
flow. This is normal, to be expected, and is due to the
design characteristics of the system.
SPIRAL-WOUND MEMBRANE
The spiral-wound membrane consists of multiple
membrane envelopes each formed by enclosing
a channelized product water carrying material
between two large flat membrane sheets. The
membrane envelope is sealed on three edges with a
special adhesive and attached with the adhesive to a
small diameter pipe.
A polypropylene screen is used to form the feed
water channel between the membrane envelopes.
A wrap is applied to the membrane element to
maintain the cylindrical configuration. The center
tube is also the permeate (product water) collecting
channel. Several elements may be connected in
series within a single or multiple pressure vessels).
WATER TEMPERATURE EFFECT
The product water flow through the membrane
is significantly affected by the water temperature.