Specifications

OPERATING INSTRUCTIONS Document No. DER04097
Effective Date 27 Nov 07 Page 5 of 7
Bowl and Conveyor Speeds
The faster the bowl speed, the faster solids are conveyed out of the centrifuge, but faster
processing results in wetter solids discharge. To reduce wetness, the slurry must remain in the
bowl longer, subjecting it to the settling process for a longer duration before being conveyed out
the solids discharge. Conversely, reducing bowl speed may be desirable for thick, heavy slurry to
maximize liquid extraction.
Since the conveyor speed is directly proportional to the bowl speed, increasing the bowl speed
also increases conveyor speed. Bowl speed is changed by replacing the motor sheave. The table
below lists the available motor sheaves and proper-size drive belts. Since changing the bowl
speed requires partial disassembly of the centrifuge, it should be done only after feed rate and
pond depth adjustments do not produce desired results. Refer to
DER05104 in Section 5 for
sheave removal and installation procedures.
GBD Centrifuge Motor Sheaves and Drive Belts
Sheave Diameter Bowl Speed (RPM) Sheave Part No. Belt Part No.
60 Hz Motor
8” 2450 10603-00 5G3V1000
9” 2750 10603-05 5G3V1000
9.9” 3000 10603-01 5G3V1000
10.6” 3225 10603-02 5G3V1000
11.1” 3400 10603-06 5G3V1060
11.5” 3500 10603-03 5G3V1060
13.1” 4000 10603-04 5G3V1060
50 Hz Motor
8” 2000 10603-00 5G3V1000
9” 2250 10603-05 5G3V1000
9.9” 2450 10603-01 5G3V1000
10.6” 2600 10603-02 5G3V1000
11.1” 2750 10603-06 5G3V1060
11.5” 2850 10603-03 5G3V1060
13.1” 3250 10603-04 5G3V1060
Gearbox Ratios
A larger motor sheave diameter increases the bowl speed but reduces the torque. Consequently,
the feed rate may have to be reduced or the gearbox changed to a higher ratio to provide
adequate torque. For example, if a 125:1 gearbox is replaced with a 52:1 ratio gearbox, the feed
rate must be reduced by 10 percent to avoid overloading the centrifuge. Since gearbox
replacement is a major alteration, it should be considered only after all other options have been
unable to produce satisfactory performance and following consultation with the Derrick Service
Department.