Plant Shutdown

On Site Vacuum Testing

Vacuum Pump Testing, Condition Monitoring, Laser Alignment and Endoscope Inspection

Recently Pump Supply & Repair Group were asked to attend the site of a Power Station in London to perform a vacuum test on two Nash pumps. In addition, our scope of work involved confirming the alignment the pump/motor using laser equipment, checking the vibration & bearing noise using condition monitoring equipment and inspecting the internal condition of the pump using an endoscope probe.

Our testing procedure involves fitting orifice test flanges, each with 18 precision cut ‘test holes’. A vacuum test gauge is attached to the centre of the plate to record pressure during the blanking off of each test hole in turn.The performance of the pump was determined by the application of mathematical formulae using the results recorded. A graph is then produced comparing the performance with the OEM catalogue curve, as can be seen in this image.

The graph shows that below 16″ Hg, the pump is performing at approx 90% of its original specification, however, above 16″ Hg performance detoreriorates rapidly, achieving only 36% at its duty point of 25″Hg.

Further investigation using our endoscope probe revealed that there was significant disintegration and corrosion of the rotor vanes, particularly at the drive end of the pump. An example of this damage can be seen on the attached image, and this almost certainly contributed to the poor performance of the pump.

Our laser alignment equipment indicated the pump to have remained in alignment in the vertical plane, however, it was marginally out horizontally: we proceded to ease the pump back into alignment, aided by the ‘live’ display given by our equipment which gives a continuously updated display of the alignment. The attached image shows the final alignment report.Our ultrasonic Condition Monitoring equipment indicated that vibration and bearing condition were all within accepted tolerances.Visual inspection also revealed on of the mechanical seals to be leaking.

Our recommendation to our customer was to remove the pump from service as debris from the disintegrating rotor could enter the process causing damage throughout the system. Our overhaul of the pump would involve Belzona coating to protect surfaces liable to the effects of corrosion and using Belzona to rebuild the profile of the rotor. As a matter of course, bearings and mechanical seals would also be changed.

For further information or to discuss any testing requirement you may have, please contact:

Site Services Manager
Email: clambley@pumpgroup.co.uk
Mobile No: 07887 721900

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