be ordered with manual or automatic
reset.
Automatic Fast Flush:
The automatic fast flush option
bypasses the concentrate control
valve, reducing the concentrate
pressure and increasing the flow of
feed water across the membrane.
The fast flush removes foulants that
may have attached to the surface of
the membrane. By removing these
foulants before they crystallize on
the surface of the membrane, the
system can operate longer without
cleaning and/or replacing
membranes. Crane Environmental
recommends the use of the
automatic fast flush in several
instances:
1. When injecting antiscalant
chemicals. These chemicals keep
scaling ions in solution up to a
higher concentration so the ions
don’t precipitate, and scale the
membrane. If the solubility
concentration is exceeded, the
ions may precipitate and scale the
membrane.
2. For feed water with a high scaling
potential (hard water) in addition to
automatic fast flush, pre-treat the
water with an antiscalant or a
softener. Do not use the automatic
fast flush instead of pretreatment.
3. Where minimal maintenance is
important, an auto flush can
increase the time between
membrane cleaning.
4. For high TDS (total dissolved
solids) applications where the
TDS exceeds 500 ppm, consider
installing an auto flush.
5. For high recovery applications
(use of a recycle valve), consider
using auto flush.
6. For systems that may remain
inoperative for long periods of
time, a fast flush should be
installed. The automatic fast flush
will not operate if the electrical
power is removed from the
system.
The auto flush option includes a
timer with two adjustable settings
that regulate its operation. One timer
setting allows you to set the interval
between flushing, and the other
timer setting allows you to set the
length of the flush time. The timer is
preset at the factory to initiate a 5-
minute flush every 10 hours. This is
based on the time the system has
electrical power applied.
In the fast flush conditions the water
flushes across the membrane in the
same direction as water flows in
normal operation; this is not a
“backwash” flow.
NOTE: Some permeate will be
produced during the automatic fast
flush; therefore, an overflow for the
permeate storage tank is
recommended.
EPRO 150-8000 O&M MANUAL Rev.04/03 Page 24 of 55
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