10. Calibration
32
1. Preparation of the instrument
Clean the instrument (‚Cleaning‘, chapter 8), fill it with distilled H
2
O and
then prime it carefully.
2. Check the volume
a) 10 dispensing operations with distilled H
2
O in 3 Volume ranges
(100 %, 50 %, 10 %) are recommended.
b) For filling pull up the piston gently until the upper stop of the
volume
set.
c) For discharge depress piston slowly and steadily without force until
the lower stop.
d) Wipe off the tip of discharge tube.
e) Weigh the dispensed quantity on an analytical balance. (Please follow
the operating manual of the balance manufacturer.)
f) Calculate the dispensed volume. The Z factor takes account of the
temperature and air buoyancy.
Depending on use, we recommend that gravimetric testing of the instru-
ment be carried out every 3-12 months. This time frame should be ad-
justed to correspond with individual requirements. The complete testing
procedure (SOP) can be downloaded at www.vitlab.com. In addition,
you can also perform a function test at shorter intervals, e.g. dispensing
the nominal volume into a volumetric test flask.
Gravimetric volume testing according to DIN EN ISO 8655-6 (for mea-
surement conditions, see ‚Error Limits‘, chapter 12) is performed as fol-
lows:
Standard deviation
