Pump housing
Monitoring cooling systems
Pumps are one of the most common and most important machines in almost any production process. Besides the detection of imbalance, misalignment and bearing damages it is also possible to detect wear and/or pollution in the pump housing with vibration measurements.
Vane pass frequency
A chemical plant, located in the Europoort in Rotterdam, has a central cooling system for the temperature regulation of a large part of their installation. A number of pumps are used to continuously feed and pressurize the cooling system. Although the number of pumps is redundant, failure of one of the pumps means a less reliable cooling system and should therefore be avoided at all times. For this reason the pumps are taken into the monthly condition monitoring program that is performed over the whole plant.
The vibration analyses on one of the cooling pumps suddenly show a strong increase of the so called vane pass frequency of the pump impeller. This frequency is caused by the vanes passing a fixed point. Although this frequency is always present, the strong increase leads to our recommendation to inspect the suction inlet and the pump housing for any wear, damage or pollution.
At the next opportunity the customer visually inspects the pump housing and discovers extensive wear on the suction side of the pump housing. Long term effects or corrosion in combination with cavitation have most probably caused a part of the inner pump housing to suddenly break free.
Spectrum analysis and a good cooperation between analyst and customer have prevented a sudden failure of the pump which would have compromised the safety of the whole factory.