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Basic Knowledge
8.8 Six-speed rotational viscometer
  • Detailed description

1. The application of six-speed rotational viscometer
The six-speed rotational viscometer is mainly used to test the rheological parameter and viscosity of Newtonian fluid and non-Newtonian fluid. To the cement slurry system, the slurry system liquidity index and consistency coefficient can be calculated with the indication tested under different speed. And you can know the rheological properties of cement slurry system by the result calculated.

2. The principle and character of six-speed rotational viscometer
The six-speed rotational viscometer is a direct-reading test device which runs by moter. The fluid tested is in the annular space between the stator and the external barrel. For every a fixed speed, the external barrel rotate at this constant speed and there is torque produced by the external barrel rotating around the stator. This made the stator rotating a corresponding angle. This angle reacts to the pointer indicator on the scale. Through the appropriate calculation formula, you can get the liquidity index and consistency coefficient.

3. The test procedure of six-speed rotational viscometer
a. Check the external barrel and stator, keep them clean and screw on the external barrel.
b. Turn on the power and rotation speed switch, pull the variable speed bars gently to the middle gear, and turn off the rotational switch.
c. Pick out the cured cement slurry from the atmospheric consistometer and put it immediately into the viscometer sample cup and up to the scale line. Then put the cup to the viscometer lift, rise the sample cup, and make the cement slurry lever equal to the external barrel’s scale.
d. Turn the rotation speed switch to low speed gear (1rmp,6rmp) and when it rotate for 10 second, write down the reading and turn to the higher speed gear and write the reading after rotating for 10 second.
e. Turn the rotation speed switch to the 100,200 rpm gear; write down the reading when it rotate for 10 second at the speed of 100rpm and 200rpm separately. Then turn the rotation speed switch to 300,600 gears; write down the reading at 300rpm rotation speed, not test the value at 600rpm rotation speed.
f. According to the decreasing speed order, write down the reading at 300, 200, 100, 6 and 3 separately, the average value is the testing reading.
g. After the experiment, put down the lift, remove the sample cup, unscrew the rotational barrel. And then clean them up completely.
h. Dry and install the rotational barrel, turn off the power.

4. The maintenance of the six-speed rotational viscometer
a. The speed only can be change when the motor is running and forbid forced variable speed if the motor is not working.
b. Clean out the sample cup and instrument, especially the bottom of stator.
c. Be gentle when clean the stator and banister brush is the better. Don’t scratch the stator.
d. The rotational barrel and stator must be dried and installed on the viscometer after washing.

Breakdown maintenance
a. Measuring error is too large
Cause: Torsion spring is not accurate
Solution method: rectify according to the torsion spring check calibration method. If the torsion spring is deformed, change it and rectify the new torsion spring.
b. The error under 300rpm, 600rpm speed is large; especially it is not rotate under the 600rmp speed.
Cause: the flexible connection set on the drive shaft is loose
Solution method: break out the top cover and bottom seat, pick out the drive shaft, and screw on the nut on the flexible connection set. If the flexible connection set is damaged, change it.