I have a problem for a vertical turbine pump. The vibration measurement shows a figure which is marginally higher than the allowance of Hydraulic Institute when the measurement is made at non-drive end of motor. If we measured at dirve end of the motor, it is within the allowable limit.

In the Handbook of Hydraulic Institute, it seems that allowable limit referred to the measurement made at drive-end position. Do you know what should be the right position for vibration measurement of vertical trubine pumps.

Respected sir,

Usually for a VTP Vibrations are always higher at non drive endof the motor.
this would be higher in the direction of overhang of the motor.
i would rather suggest to increase the stiffness of the motor.

I agree with the previous reply.

In addition I would suggest checking the bolt torque on the motor flange and check for "soft foot" at the flange. Put a dial indicator on the motor so it measures any movement of the motor housing as you loosen and retighten each flange bolt. If there is more than .003" (.08mm), shim the flange or re-machine it.