Brookfield DV-E Viscometer - Manual (Page 14)

Brookfield Engineering Labs., Inc. Page 14 Manual No. M98-350-J0912
cP
12RPM %
S02
(MOTOR ON)
Figure II-5
cP
12OFF %
S02
(MOTOR OFF)
Figure II-6
Note: When the motor switch is in the ON position, any change to the selected speed
will be effective immediately. When collecting data at multiple speeds, you
may wish to leave the SPEED/SPINDLE switch in the left position to facilitate
speed changes. Also, when the motor switch is turned off, the display will hold
the last measured torque value and measured viscosity.
The DV-E Viscometer employs an optical signal pick-up inside the instrument to detect the torque
value of the calibrated spring. This optical signal pick-up is recorded four times per revolution of
the spindle. When the spindle begins to rotate at a defined speed, four torque values are recorded
during the first full revolution of the spindle and averaged together. The display reports the average
value for both torque (%) and viscosity (cP or mPa•s). Thereafter, the next torque value recorded by
the optical signal pick-up is averaged together with the three preceding torque values and the newly
calculated torque (%) and viscosity (cP or mPa•s) values are then displayed. This 4x revolution
pick-up and display continues as long as the motor is on.
This algorithm in the instrument firmware is used for all viscosity and torque readings. Consequently,
the wait time to observe the initial displayed readings for torque and viscosity increase as you go
to lower speeds.
It may also be necessary to allow time for the indicated reading to stabilize.
Note: At speeds of 1 RPM and lower, additional time may be required to allow for
complete deflection of the torque sensor. The % (torque) and cP (viscosity) will
flash until 1 revolution is achieved and the % torque value is greater than 10%.
The time required for stabilization will depend on the speed at which the Viscometer is running
and the characteristics of the sample fluid. For maximum accuracy, readings below 10% should be
avoided. Additional information on making viscosity measurements is available in Appendix B or
the Brookfield publication “
More Solutions to Sticky Problems” .
The DV-E
Viscometer will remember the selected speed and spindle when power is turned off. On
start-up, the Viscometer will be set to the previously selected spindle and speed.
Please see Brookfield publication “
More Solutions to Sticky Problems”
(Chapter 3) for information
on how to select a speed.