Hach-Lange FILTERTRAK FT 660 sc Basic User Manual - Manual (Page 15)

Table 1 Interpretation of verification values
Verification values Result identified Suggested action
± 5 mNTU of the
baseline
2
The instrument is
calibrated. None
- 5 mNTU (or less) of
the baseline
2**
The instrument is not
calibrated.
1. Clean the instrument.
2. Do the verification again.
3. Recalibrate the instrument
if necessary.
4. If recalibrated, assign a
new baseline value.
+ 5 mNTU (or
greater) of the
baseline The instrument body
may be contaminated.
There may be fluid on
the optical surface of the
dry standard.
1. Clean the body of the
instrument, bubble trap,
detector and dry standard.
2. Recalibrate the instrument.
3. Assign a new baseline
value.
* If the instrument consistently does not meet the PFC, contact the
manufacturer.
** A significantly low value is 25% or less of the expected value. A significantly
low value may occur because the light source or detector is not working
correctly. If the verification value is consistently significantly low, send the
instrument to the manufacturer for service.
Verification with a dry standard without software
This procedure includes instructions on how to:
• Assign an initial baseline value to the dry standard without dry
standard software
• Do a dry standard verification without dry standard software
Find and store the baseline value for the dry standard immediately after
the instrument is calibrated and after every subsequent calibration. Refer
to
Assign a baseline value to the dry standard on page 15.
The baseline value is referenced for subsequent calibration verifications
until the next calibration.
Note: This procedure can be done on instruments that use the AquaTrend ®
controller by manually recording the baseline value for the dry standard, pass or fail
criteria (PFC) for verification and verification value.
Note: When not in use, keep the dry standard in the protective case.
Assign a baseline value to the dry standard
1. Remove the head assembly from the body of the instrument.
2. Remove the dry standard from the protective case. Refer to
Figure 8
on page 14.
3. Clean, dry and inspect the dry standard.
a. Use the disposable wipes provided to clean the dry standard.
b. Use a dry cloth to dry the top
1 /
3
of the dry standard. Refer to
Figure 8 on page 14.
c. Make sure that the glass of the dry standard is free of chips and
scratches.
4. Install the dry standard.
a. Put the dry standard in the aperture plate. Make sure that the
locking pin goes in the notch in the aperture plate. Refer to
Figure 8 on page 14.
b. Turn the dry standard 1 /
8
of a turn clockwise until the dry standard
locks in position.
c. Use a dry cloth to remove any fingerprints and oils from the glass
of the dry standard.
5. Put the head assembly on the body of the instrument.
6. When the instrument reading is stable, record the value.
This value is one of three values that will be used to calculate an
average value. The average value will be the final baseline value.
7. Prepare the dry standard to be measured again.
a. Remove the head assembly from the body of the instrument.
b. Turn the dry standard
1 /
8
of a turn counter-clockwise, then
remove the dry standard from the aperture plate.
c. Do steps 3–5.
8. When the instrument reading is stable, record the value.
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