FCI Watermakers MAX-Q+, User Manual & Installation Manual

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FCI WATERMAKERS, INC. 5 FCI WATERMAKERS, INC. General
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.
If the feed water flow is insufficient, the salts are saturated at the boundary layer
and can readily adhere to and pack into the R.O. membrane element surface.
For this reason, it is important to maintain sufficient feed water flow through
the R.O. membrane element and prevent concentration polarization.
BRINE VELOCITY
The brine velocity, or 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. The salts 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 provides 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 R.O. membrane element is subjected to elevated pressures
beyond 1000 PSI, the product water channel becomes squeezed,
resulting in restriction and 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.
Following terms are helpful in becoming familiar with
a FCI Watermakers Reverse Osmosis System.
GLOSSARY OF TERMS