Metrohm 700 Dosino - Manual (Page 45)

4. Appendix
700 Dosino, Instructions for Use 39
( )
1
2
−
−
=
∑
n
V V
s
i
s : repeatability standard deviation
V
i
: distributed volume
n : number of distribution
Please note
• The above-mentioned limits are related to water at 20 °C and
are valid for dosing units with glass cylinders only.
• The nominal volume of the dosing cylinders are printed on the
housing of the dosing units.
• The above-mentioned limits are valid for the useful volume ran-
ge of 10 % to 100 % of the nominal volume.
• The error limits relate to the ISO 8655-3 Draft International
Standard (Piston-operated volumetric apparatus - part 3: Piston
burettes), which is to come to effect in the year 2000.
• Metrohm burets with glass cylinders in general have a better
quality performance (systematic and random error) than the
maximum error limits implied. Check your dosing system ac-
cording to the ISO test specification.
Possible sources of dosing errors
Influencing parameters are:
• Air bubbles in the dosing cylinder or tubings.
• Leaky piston/cylinder system.
• Leaky tubing connections.
• Differences in hydrostatic pressure of the liquid level in the
supply flask versus the dosing tip.
• Viscosity and/or flow characteristics of the liquid to be dosed.