VWR avantor EHP Instruction Manual page 10

Periodic checks of the operation of the pipettor are
recommended at least once per year. Frequency of
checks should be increased depending on workload,
sterilization or autoclave processes, and frequency of
replacement of component parts.
If during pipettor operation the accuracy error (the
difference between the real aspirated volume and the
preset volume) exceeds the permissible value given
in the table in Section 5, pipettor recalibration should be
carried out.
Recalibration of the pipettor involves setting the counter
to the value of the liquid volume obtained by weighing.
Recalibration of the pipettor is valid only for one liquid
volume drawn by the pipettor.
The recommended volume for recalibration is 10%
of the maximum (nominal) value or minimum volume
depending on which of these values is greater. See table
on page 18 for more details.
Parameters for Checking the Pipetting Accuracy
The pipetting accuracy is influenced by factors such as:
tips used, characteristics of the pipetted liquid (density,
viscosity), and operating conditions (ambient tempera-
ture, pressure).
To determine the accuracy error of the pipettor, the
following conditions should be met:
• Ambient temperature and temperature of the pipet-
tor, pipet tips, and liquid should be within the range
of 20°C to 25°C and stabilized during weighing within
±0.5°C.
• Measurements should be conducted using distilled
water.
• Balance sensitivity should be suitable for the volume
"V" to be measured:
Volume Checked
(V, μL)
0.1≤V≤10
10≤V≤100
100≤V≤1,000
V>1,000
18 – VWR EHP PIPETTORS
Balance Sensitivity
(mg)
0.001
0.01
0.1
0.1
• When calculating the liquid volume aspirated by
the pipettor, the conversion factor (Z) (μL/mg) for dis-
tilled water or a liquid with comparable density should
be taken into account. Sample values of conversion
factors are given in the following table.
Temperature
(°C)
95.0
20 1.0028
21 1.0030
22 1.0032
23 1.0034
24 1.0037
25 1.0039
See ISO 8655 for the full table of conversion factors (Z).
NOTE: Pipetting should be performed in accordance
with guidance described in Sections 7 and 8.
Checking the Pipetting Accuracy Parameters
Fixed Volume
Nominal
volume Permissible values
(µL) (μL)
5 4.95
10 9.95
20 19.84
25 24.80
50 49.60
100 99.20 100.80
200 198.80
250 248.50
500 497.50 502.50
1,000 996.00 1,004.00
Pressure (kPa)
101.3 105.0
1.0029 1.0029
1.0031 1.0031
1.0033 1.0033
1.0035 1.0036
1.0038 1.0038
1.0040 1.0040
Volume Change ΔV
(μL) for a Turn of
a Calibration Key by
1
Turn Increment
5.05 0,33 0.0137
10.05 0,33 0.0137
20.16 0,63 0.0262
25.20 0,63 0.0262
50.40 2,50 0.104
2,50 0.104
201.20 6,30 0.262
251.50 25,0
25,0
25,0
Instruction Manual – 19
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1.04
1.04
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