RADWAG AS R2, User Manual

Page: 67 / 96

- 67 -
11.13. PIPETTES CALIBRATION
Caution! Function valid for AS R series balances exclusively.
Pipettes calibration function applies to fixed volume pipettes and adjustable volume pipettes. During
volume testing procedure, the software determines accuracy and repeatability errors. In case of
pipettes with adjustable volume, errors for Max, Min and ½ Max volume are estimated.
All pipettes are tested for adherence to requirements of PN-EN ISO 8655:2003. During the tests
dosing repeatability and accuracy are monitored.
In order to ensure the highest accuracy of pipettes calibration process, maintain the following
ambient conditions at a workstation:
•
Ambient temperature of a pipette, tips and liquid should be kept between 20°C - 25°C with
change rate during testing within ± 0.5°C,
•
Relative humidity 50 - 75%;
and
•
Use distilled water for pipettes calibration processes,
•
Make sure that a pipette, tips and distilled water are thermally stabilized in the room intended
for weighing operation performance. The reference standard advises that minimum
acclimatization time for above mentioned is 2 hours.
Prior pipettes calibration start, it is necessary to install a dedicated set inside the draft shield. The set
is not a standard balance equipment. The picture below presents set installation. Evaporation ring
minimizes measurement errors being a result of evaporation of liquid occurring in course of the
weighing process.
Prior to pipettes calibration pour 2/3 of the evaporation ring with distilled water. The set is ready to be
used after about 1 hour – it takes this long for humidity to stabilize. Excess water can be removed
using automatic pump or an external pipette.
To minimize any humidity changes inside the chamber and to avoid air draft influence while opening
the door, dose the liquid from a pipette to an evaporation ring via an opening of a weighing chamber
lid.
With thus prepared balance you can start pipettes calibration procedure.
11.13.1. Additional settings of pipettes calibration mode
Apart from standard settings for this mode (i.e. weighing mode settings) some additional parameters
have been designed to describe operation of the mode.
Additional settings list:
•
VOLUME DETERMINATION – allows to predefine number of tested volumes for a particular
pipette. For pipettes with fixed volume please set parameter <1>, for pipettes with adjustable
volume set parameter <2> and <3>.
•
MEASUR. NO – allows to predefine number of measurements for each tested volume. Number
of measurements ranges from 6 to 20.
•
AUTOMATIC TARING - allows to turn on function of automatic taring of dosed portion of water
after confirmation of measurement (value set to <YES>)
Remember to select correct values of the above options before pipettes calibration procedure is
performed. The settings should reflect expectations and needs being a result of working environment.