Opti-Trace User’s Manual
Page
9
6.
While viewing the 4-20mA measurement, adjust the trim-pot located below the
calibration port marked "Blank". Counterclockwise adjustment will lower the
measurement, clockwise will increase the measurement. A setting that results in
approximately 4mA will yield the best results. As the measurement is in real time
there will be some "noise" in the 4mA measurement - achieving exactly 4.00mA
is not realistic. Remove the syringe.
7.
Note that if your minimum sample has a large fluorescence value, it may not be
possible to adjust the minimum level to 4 mA. If this happens, adjust the blank
adjustment until the output of the sensor is as low as possible.
Sensitivity Adjustment Steps:
1.
Turn off the process water flow to the Opti-Trace.
2.
Ensure the discharge plumbing of the Opti-Trace is not pressurized. If required,
temporarily install a DVM capable of mA measurements. The connection points
must be in series wth the 4-20mA wring to yield accurate measurements, (See
Appendix B for wiring details).
3.
Determine the maximum range of your application and prepare the appropriate
fluorescent dye solution equal to approximately 50% of this maximum (equal to
~12mA measurement).
4.
Using the provided syringe, inject 120cc of the known concentration of
fluorescent dye significant for your application into the calibration port.
5.
While viewing the 4 - 20mA measurement, adjust the trimpot located below the
calibration port marked "Sensitivity". Counterclockwise adjustment will lower
the measurement, clockwise will increase the measurement. As the measurement
is in real time there will be some "noise" in the 12mA measurement - achieving
exactly 12.00mA is not realistic.
6.
Remove the DVM temporarily installed for calibration purposes. Return the
Opti-Trace to service by turning on the process water flow.
7.
Note that if your sample is out of the range of the Opti-Trace, it may not be
possible to adjust the output to 12 mA.
Section 3
– Characterizing for Standalone Use
Equipment Required
a)
Opti-Trace fluorometer configured for dye of interest
b)
DC Power Supply, Output Voltage Range 5 – 30 VDC
c)
Multimeter to read 0 – 20 mA
d)
Sample of de-ionized water
e)
Sample of water with dye at a known concentration, say 30 ppb.
