Hach-Lange TENSETTE plus User Manual - Handbuch (Seite 27)

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Section 5 Calibration
All Hach TenSette plus are factory calibrated and adjusted to give the
volumes as specified with distilled or deionized water. Normally, the
pipettes do not need adjustment, but they are constructed to permit
recalibration and adjustment for liquids of different temperature and
viscosity.
5.1 Device requirements and test
conditions
An analytical balance must be used. The scale graduation value of
the balance should be chosen according to the selected test volume
of the pipette:
If the uncertainty of measurement of the balance is known, this may
be used instead of the repeatability and linearity.
Test liquid: Water, distilled or deionized, “grade 3” water conforming
ISO 3696. Tests are done in a draft-free room at a constant (±0.5 °C/
±33 °F) temperature of water, pipette and air between 15 °C (59 °F) to
30 °C (86 °F). The relative humidity must be above 50%.
5.2 Calibration Counter
By selecting MENU → OPTIONS → CALIBRATE → COUNTER the
number of pipetttings since last calibration is shown on the display.
The counter is reset to zero when calibration is performed.
5.3 Checking the calibration
The pipette is checked with the maximum volume (nominal volume)
and with the minimum volume. A new tip is first pre-wetted 3–5 times
and a series of ten pipettings are done with both volumes. A pipette is
always adjusted for delivery (Ex) of the selected volume. Measuring
volumes taken from balance is not allowed.
Table 1 Test Conditions
Volume range
Readable
graduation
Precision
repeatability(s)
and linearity
Uncertainty
of measure-
ment
10–100 µL 0.01 mg 0.02 mg 0.02 µL
above 100 µL 0.1 mg 0.2 mg 0.2 µL