ALTANA BYK-Gardner Dip Viscosity Cups Zahn Type - Manual (Page 8)

7
Operation
Operation
Refer to the ASTM D 4212 for a comprehensive
procedure. For general purpose use the following
procedure:
1. Choose the proper cup for the expected
viscosity of the liquid to be evaluated. The time
for the cup to empty should be between 20 and
80 seconds.
2. Immerse the cup and a thermometer in the
sample container and stir the sample well
to ensure uniform temperature and density.
Allow the cup to remain in the fl uid for at least
5 minutes to allow the cup temperature to
stabilize. Record the temperature.
3. Lift the cup out of the container allowing
the cup to hang vertically from your fi nger by
means of the ring
4. As the top of the cup breaks the surface of
the sample, start the timer. Hold the draining
cup not more than six inches above the liquid
level in the container.
5. Stop the timer at the fi rst defi nite break in
the stream at the base of the cup. The effl ux
time, or time for the cup to empty, constitutes
its viscosity.
6. Report cup number, temperature and time in
seconds.
7. Following each determination, clean the cup
with a suitable solvent and a soft cloth or soft
brush. Use no metal tools to clean the cup
as even minor nicks or wear of the precision
drilled orifi ce can result in substantial variations
in readings.
8. Fluids can vary dramatically with
temperature. It is not unusual even with
standard oils to experience changes of 18%
per degree centigrade. If it is not practical to
control temperature to tight tolerances, the
temperature of the fl uid must be noted and