PART FOUR - SERVICE AND MAINTENANCE
SECTION 2 - PRESERVING MEASUREMENT ACCURACY
Rev. 2-300
Accu4™ Low-range Turbidimeter System
87
2.2 Keeping Flow
Chamber Clean
2.3 Keeping System
Calibrated
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2.4 Avoiding Electrical
Interference
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The Accu4™ Low-range Turbidimeter System has reactive
diagnostics to alert you when the sensor flow chamber
needs cleaning. When an abnormal system diagnostic con-
dition has been detected, the MEASURE screen will flash
the “WARNING CHECK STATUS” message. Depending on
the selected activation mode for a STATUS relay (FAIL,
WARN or ALL), this may or may not automatically energize
a STATUS relay corresponding to that specific type of con-
dition. To determine if the sensor needs cleaning, display
the “STATUS: SENSOR” screen in the TEST/MAINT menu
branch. When this screen indicates:
•
CHAMBER DIRTY -- System diagnostics has detected
degrading measurement performance, typically caused
by dirty flow chamber windows. Refer to Part Four, Sec-
tion 1.1 for instructions to clean the flow chamber.
•
OK -- Check the other status screens to determine the
condition causing the warning message.
Depending on the circumstances of the application, periodi-
cally verify system calibration to maintain measurement
accuracy.
Maintenance Tip!
Upon startup, frequently check the
system until operating experience can determine the
optimum time between calibrations that provides ac-
ceptable measurement results.
Calibrate the system using an appropriate method. Refer to
Part Three, Section 5 for details.
A common cause of
measurement error is calibrating with an incorrectly
prepared formazin suspension.
NOTE:
When calibrating with a formazin suspension,
carefully prepare the suspension using Class A
laboratory glassware and correct analytical tech-
niques. This is very essential to attain accurate
measurement results.
Recommendation:
Do not run the sensor cable (and inter-
connect cable, if used) in the same conduit with line power.
Maintenance Tip!
Excess cable should not be coiled near
motors or other equipment that may generate electrical or
magnetic fields. Cut cables to proper length during instal-
lation to avoid unnecessary inductive pickup (“electrical
noise” may interfere with sensor signal).
