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centration of the diluted feed stream, at the operating recovery, is that the water in the
machine at shutdown will have total dissolved solids (TDS) concentrations approximate-
ly equal to the machine feed TDS level. The low TDS environment created reduces the
potential for membrane element fouling during the down period, extending membrane ele-
ment life. The purge operates for a ten (10) minute period. During this period, no per-
meate is discharged from the machine and concentrate flows from the machine at the nor-
mal operating rate. When the cycle is complete, the RO pump will shut down. When the
request to restart is received, the RO will restart and operate as normal. If the restart sig-
nal is received during the Purge Cycle, the cycle will terminate and the RO will return to
normal operating mode.
Since this feature is designed to provide a low TDS environment during extended shut-
down periods, the purge sequence will not activate for any factory-configured shutdown
event (i.e., ON/OFF switch, alarm shutdown, etc.). These shutdown events are assumed
to be typically short down periods. Also, activation of the purge cycle for these events
may be undesirable if immediate shutdown is required. The purge cycle will activate
when a shutdown request is made by an external component that is configured for purge-
activated RO shutdown.
Level control of a permeate storage tank is GE Osmonics’ standard external control device
which activates the purge shutdown. Any other remote device(s) can be used where per-
meate purge is desired prior to RO shutdown. Examples include: remote ON/OFF, post-
treatment lockout, etc.
W
ARNING
: DO NOT CONFIGURE PRETREATMENT DEVICES FOR
PURGE-ACTIVATED SHUTDOWN. THE PURGE CYCLE
REQUIRES THE FEED WATER SUPPLIED BY THESE
DEVICES.
To establish the control loop for purge-activated shutdown, perform the following steps:
W
ARNING: BEFORE OBTAINING ACCESS TO TERMINALS, ALL SUPPLY
CIRCUITS MUST BE DISCONNECTED.
STEPS
1. Establish that the remote device(s) has dry contacts available to provide the shut-
down signal to the RO.
2. With power removed from the control enclosure, open enclosure.
3. Wire from the 24VDC source terminal #515 to the first remote device. Wire all
additional devices in series with the first. Wire from the last remote device to ter-
minal #1007.
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