User Calibration Procedure - VWR Digitrate Pro Manual De Uso

User Calibration Procedure

The user is allowed to override Factory Calibration and custom calibrate the Digitrate Pro.
The procedure is as follows:
1. Establish a mean volume of 10 dispensings of nominal volume of distilled H20 at 20 °C (e.g 50 ml for the
50 ml unit), and establish the mean value gravimetrically. After each filling, remember to reset the display
(18) to 00.00, only after you have compensated for any backlash.
2. When the mean volume, taking into account the correction factor (see formula below), has been
established, turn the titrate wheels so that nominal volume is displayed i.e. 50 ml for the 50 ml unit.
3. With the instrument turned on, press the calibration switch (17) through the right hand pen hole.
4. The LCD will flash 'CAL'.
5. Use the 'ON' button (15) as '–' and the 'Reset' button (18) as '+' to set the calculated mean volume on
the display. Push once for increment of '1' – continuous push runs the numbers faster.
6. Store the new value by pressing the 'MODE' button (16). The word 'CAL' appears on the display from
now on in order to indicate that the unit has been calibrated by the user.
Calculation (for the nominal volume)
xi
Mean value x =
n
x = results of the weighings
i
n = number of weighings
Mean volume V = x*Z
Z = correction factor (e.g. 1.0029 μl /mg at 20 °C, 1013 hPa)
Calculate the dispensed volume by taking the temperature into account
(1 ml distilled water at 20 °C = 0.997 g)
Factory calibration figures, however, are retained in the memory at all times.
To return to the factory calibration:
1. Press the calibration button through the pen hole twice.
2. The display cancels the word 'CAL' and the unit is returned to the factory calibration.
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