# Topic: Re: How do I calculate the dynamic force on the agitator?

posed by
Explaining "how" to calculate the dynamic force on the agitator is more difficult than providing a value for the conditions described.&nbsp; Further, "how" the "dynamic force" will be used makes a difference in the suggested safety factors to be applied to the calculated values.&nbsp;For the purposes of equipment design, the dynamic forces should be calculated based on the motor horsepower and agitator speed, since at some viscosity the motor could be fully loaded.&nbsp; On that basis, torque will be about 11,000 N-m.&nbsp; An estimate of the bending load on the shaft and drive is about the same, 10,000 N-m.&nbsp; Those loads require a 125 mm diameter shaft.&nbsp;For the purposes designing a support for the agitator, a rigid mounting is necessary.&nbsp; The support should be designed to handle 2.5 times the calculated torque and 3.0 times the calculated bending load.&nbsp;If all that is needed is an anticipated operating load for the dimensions and viscosity described, the agitator will require about 33 hp.&nbsp; That requirement is based on a viscous power number of 360 (for laminar operation), which is multiplied by a factor of 2.2 for the impeller Reynolds number of about 1,000.&nbsp; The resulting viscous (not turbulent) power number is 780.
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