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.

Keith,

the vibration will almost always be higher at the non drive end of a vertical machine. Place your elbow on the desk and move your hand back and forth. This is how a vertical machine vibrates. Your elbow isnt moving much compared to your hand. rules of vibration are out the window on vertical motors. You have to take into consideration the hieght from the floor, type of base the motor is on, the rigidity of the base when deciding how much vibration is too much. I try to compare like machines for a starting point.

i work in the water treatment industry and most of the pumps i see are vertical turbines. For a motor with the upper bearing 6 feet off the ground on a rigid base i dont get excited about vibration levels until i see over .300 ips peak.

Keith,

What other people have suggested is okay. But before proceeding please take bump test to know wheater you have increase mass or stiffness.
This will resolve the all the vibrations to lower level and equipments life cycle will increase with small maintennace activity.