Measurement Of The Falling Times - Thermo Scientific HAAKE Instruction Manual

Measuring

9.2 Measurement of the falling times

The jacket tube snaps into a defined 10-position at the bot-
tom of the instrument.
By turning over the jacket tube, the ball is set to the measu-
ring position.
The falling time of the ball moving from the ring mark A to ring
mark B is determined by using a stop watch. The time period
starts when the lower periphery of the ball touches the ring
mark A, which must appear as a straight line. The falling time
ends when the lower periphery of the ball touches the ring
mark B, which again must appear as a straight line. If one
uses the distance AC or CB to reduce very long falling times
for high viscous liquids the double of the measuring time pe-
riod must be taken into account.
Turning the jacket tube 180 again the ball returns to its start
position. It is good practice to take the mean value out of sev-
eral falling time values (3 to 5).
When testing dark liquids it is usually very difficult to see the
lower part of the ball. In this case we advise to take the ball
equator when it passes through the ring marks.
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