Xylem TB500 ONLINE TURBIDITY ANALYZERS - Manual (Page 28)

TB500 (2/07)
Rev. 1.0 24
8.0 Additional Features and Options
8.1 Backlit LCD
The backlit LCD allows for easier readability of the LCD display in low light or no light
conditions. The backlight is intended for continuous operation. The brightness is
adjustable from a menu in the CONFIG mode.
8.2
Ultrasonic Cleaning (Models TB504-WL & TB504-IR)
This factory installed option is used to continuously clean the flow through cuvette. It is
not intended to clean cuvettes that are already dirty, or replace manual cleaning entirely.
The system will increase the time between cleanings dramatically. Please note that the
system requires the use of a special cuvette. This cuvette must be used for the system to
operate correctly.
The system works by sending an ultrasonic frequency through spring connections into a
piezo transducer bonded to the bottom of a flow through cuvette (refer to figure 6).
The system can detect that an incorrect cuvette is installed, an error has occurred in the
transducer or the transducer is not making contact with the spring connections. This error
is indicated by CLN being posted to the lower screen. Since this is an error condition, the
alarms will be set and the 4-20 mA will be sent to 2 mA.
If the correct cuvette is installed, and the error is still posted, try rotating the flow through
unit slightly to improve the connection. If this fails to work, the cuvette may have to be
replaced (Model # TB500-UCUV). The detection for this cuvette only operates in AUTO
mode. If the system is operating correctly AUTO will flash on the display.
Note: The cuvette must be completely dry before it is inserted into the sensor. If there is
any visible moisture present on the cuvette or transducer, there is a great risk of
damaging the sensor electronics and the transducer. Be sure to clean and dry the
cuvette completely just before inserting it into the sensor.
After installing a cuvette, there will be a 30 minute period where the lower screen will
post DRY to the lower screen. During this time, the ultrasonic circuit will not operate to
allow the Vapor Purge system to remove all moisture from the ultrasonic transducer. The
Vapor Purge system can NOT remove large droplets of water, only residual moisture. The
DRY
message is normal and is not considered an alarm condition; therefore no alarms
will be implemented. If the cuvette is removed during this period no CLN alarm is posted
until the 30 minute DRY period times out.
Note: For the Vapor Purge system to function properly, all instrument seals must be
maintained and the desiccant pack must be in good condition (no DESC display).