Chemtrac Systems, Inc.
Page 32
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Chemical Period: The Chemical period setting determines the duration of
the chemical pump on time. It is recommended to use default value of 8
seconds. Excessively long chemical period (or too highly of a concentrated
chemical like Acid) can damage the probe. The value can be increased or
decreased by pressing the p or q key. The value can be changed from 1
to 20 at 1second increment.
y
Wash Period: The Wash period setting is only applicable for the SMM. For
the Dura-Trac with flush option, this setting should be left at 30 sec. The
Wash Period setting determines the duration of the sensor’s chemical
washing. Harder to remove scale or deposits will require longer Wash times.
It is recommended to only use a Wash duration that is no longer than
required to remove scale/deposits. Excessively long Wash durations (or too
highly of a concentrated chemical like Acid) can damage the probe. The
value can be increased or decreased by pressing the p or q key. The value
can be changed from 1 to 99 at 1second increment.
z
Hold Period: The Hold period setting determines how long the monitor’s
output will be held stable (or frozen at last output value before the flush) after
the flushing is finished. Flushing will cause the actual monitor reading to
fluctuate, thus it would adversely affect an automatic chemical feed control
program running through a Supervisory Control and Data Acquisition
(SCADA) or Distributed Control Systems (DCS). For this reason, the Hold
feature has been provided and must be properly set to avoid the flushing
sequence from interfering with Automatic Chemical feed control. The Output
of the monitor is automatically held stable during the flush, however, the
operator must determine the Hold duration after the flush is finished. To
determine the proper Hold setting, record the streaming current value before
the flush starts and then time how long it takes for the monitor to reach the
previously recorded reading after the flush is completed (this must be done
while the monitor is online with treated water passing through the sensor).
The simplest way of doing this will be to record the reading and then change
the Man. Flush from “Off” to “On” as this will activate the flush sequence. If it
takes 30 seconds for the reading to stabilize to the previously recorded
reading, then set the Hold setting for 1 minute. If it takes 50 seconds, then it
is recommended to set the Hold for 2 minutes. The value can be increased
or decreased by pressing the p or q key. The value can be changed from 1
to 99 at 1 minute increment.
{
MAIN Function Key: Pressing this key will ignore any setting modifications
on this screen and brings up the MAIN screen.
|
FLUSH Function Key: Pressing this key will activate a one-time manual
flush. This can be done at anytime regardless of the Auto Flush mode.
}
SAVE Function Key – Pressing this key will save current setting
modifications and brings up the MAIN screen.
Figure 11 shows the timing diagram of the Sensor Flush.
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