BRAND Dispensette S Instrucciones De Manejo página 67

7 Checking the Volume (Calibration)
Depending on use, we recommend that gravimetric testing of the instrument be carried out every 3–
12 months. This time frame should be adjusted to correspond with individual requirements.
Gravimetric volume testing according to DIN EN ISO 8655- 6 (for measurement conditions, see Error
limits, p. 66) is performed as follows:
1. Prepare the instrument
Clean the instrument (Cleaning, p. 70), fill with distilled water, and prime carefully.
2. Check the volume
a.
10 dispensing operations with distilled H
mended
b.
For discharge, depress the piston slowly and steadily without force until the lower stop
c.
Wipe off the tip of the dispensing tube.
d.
Weigh the dispensed quantity on an analytical balance. (Please refer to the user manual of the
scale manufacturer.)
e.
Calculate the dispensed volume. The Z factor takes account of the temperature and air buoy-
ancy.
Calculation (for nominal volume)
x = weighing results
i
Z = Correction factor (e.g. 1.0029 µl/mg at 20°C, 1013 hPa)
Mean:
Coefficient of variation*:
100 s
CV% =
V
*) Accuracy and coefficient of variation are calculated according to the formulas of statistical quality
control.
Test Instructions (SOPs) are available for download from
997490
O in 3 volume ranges (100%, 50%, 10%) are recom-
2
n = number of weighings
Mean volume:
Standard deviation*:
NOTICE
www.brand.de
7 Checking the Volume (Calibration)
V = nominal volume
0
Accuracy*:
V – V
0
A% =
* 100
V
0
.
Operating manual
67