Periods Without Operation; Reproducibility Of Results; Viscometers Within Quality Assurance Systems - Xylem SI Analytics ViscoPump II Mode D'emploi

ViscoPump II

4.3 Periods without operation

If the capillary viscometers are not used over a long period of time, the liquids contained in the
system, in particular aggressive solutions, have to be drained. If the liquid is left in the system, one
has to reckon that the solutions used will alter in the course of time and attack the glass, in particular
the capillaries.
Notice
Cleaning agents should be matched to the previous samples or impurities.
In many cases, an aqueous cleaning agent (glass cleaners, detergents) or organic solvents (such as
acetone or hydrocarbons) are sufficient.
Caution
Strong oxidizing cleaning agents such as chromic acid may only be used by trained personnel
and must be suitably disposed for safety and environmental reasons - the current guidelines for
handling hazardous materials must be observed.
Note
In the last rinse cycle, the viscometer should be rinsed with a suitable solvent with a low boiling
point (such as acetone), and dried by an air flow, which is preferably generated by underpressure
(for example, water jet pump). The viscometer is dry and dust-free by this treatment and can thus be
used for manual and automatic measurements.

4.4 Reproducibility of results

The measurement or analysis results depend on a variety of factors. Please check the plausibility
of the measurement results or analysis results at regular intervals, and carry out the required
reliability tests. In this regard, please adhere to the usual validation procedures and especially to the
"Viscometers within quality assurance systems" chapter.

4.5 Viscometers within quality assurance systems

Recommendations for companies that have introduced a quality assurance system in accordance
with the DIN EN ISO 9001 standards. In this quality assurance system, an inspection of the measuring
equipment is planned. The intervals and required accuracy can be defined by each company
according to its own requirements. The standard DIN/ISO 10 012, Part 1 serves as a guideline in this
matter. We recommend regular inspection of the viscometers in defined intervals.
Inspection of the viscometer constants:
a) Calibration using comparative measurements with reference measuring standards
Comparative measurements must be performed with a viscometer (reference measuring standard)
which was tested at the PTB (Federal German Physical-Technical Institute) and provided with a
constant. During this comparative measurement, the viscometer to be inspected and the PTB - tested
viscometer were placed simultaneously in the same thermostat bath. The test liquid tested, the
viscosity of which must not be known exactly, is filled into both viscometers, tempered and the flow-
through time then measured. The constants of the viscometers to be inspected are then calculated
according to the following equation:
K ⋅ t
K = PTB PTB
t
K constant of the tested viscometer
K constant of the standard reference viscometer
PTB
t low time (HC) of the tested viscometer (corrected by Hagenbach-Couette)
t flow time (HC) of the standard reference viscometer (corrected by Hagenbach-Couette)
PTB
Maintenance and care of the device and the viscometers
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