Vibration Analysis

The vibration analysis equipment can tell when a normal vibration exceeds acceptable levels and may end up becoming a problem. It also allows to determine the source and the cause of the vibration, so it becomes an aid in preventative maintenance and solving of failures.

Factors affecting the vibration

– Unbalance of rotating parts and rotor balancing

The unbalance of the rotor of the pump can generate large forces of imbalance resulting in excessive loading of the bearing and shaft and induction of high levels of vibration. The magnitude of the pump vibration caused by unbalance of the rotor is also affected by the mass of the housing of the pump, inasmuch as the pump housing increases, the magnitude of the vibration measured on support of bearings decreases.

– Natural Frequency and Resonance

Operating a pump at a frequency close to passing the pump or one of the natural frequencies of the lower rotational structure can result in resonant condition.

– Hydraulic resonance in pipe

Vibration problems may be caused by resonance of the hydraulic fluid within the system pump / tubing. When pressure pulsations induced by the pump are reflected by the pipes being added to the pulse from the source system, the pulse amplitude is increased. Resulting high pressures can cause mechanical failures in both the pipe and in the components of the pump, which could generate unacceptable levels of noise and vibration cause of system components.

Experience has shown that the following measures may prove to be effective in correcting the hydraulic resonance:

  • a) modify the resonant pipe
  • b) change the rotation of the pump;
  • c) change the internal characteristics of the pump projects
  • d) put a damper (damper) on the system pump / pipe.
    Modifications at the pump, piping or support structures that do not change the response of the pulse (hydraulic natural frequency) system pump / pipe not correct the resonant condition.

    – Hydraulic Disturbance

    The following is a list of some hydraulic disturbance:

    • a) recirculation and radial forces at low flows;
    • b) separation of the fluid at high flow rates
    • c) due to problems with cavitation NPSH;
    • c) disturbances in the flow at the pump inlet due to inappropriate design
    • e) air supply or liquid aeration;
    • f) hydraulic resonance in piping
    • g) solids contained in the liquid, as waste water, colliding with the pump and causing unbalance.

      – Other mechanical problems

      shaft misalignment, damaged bearings, bent shaft and inadequate pipe supports are also frequent causes of vibration. The following shows an example of data sheet lifting vibrations.

      Survey Data vibration