MATERIALS HANDLING
On
James Boyle reveals why a duty of care for pumps is an essential requirement to avoid downtime
STANDBY A common multistage pump O
pinion varies on which method of duty/standby pump configuration delivers the greatest
benefits in terms of efficiency and cost effectiveness. However, regardless of the method chosen, not all systems are being managed effectively – if implemented at all. Here, we assess the pros and cons of each configuration and which will provide optimum performance for maximum system uptime. Standby equipment is intended to
minimise downtime and keep process systems running. There are two distinct schools of thought when it comes to implementing standby pumps. This first is a duty/standby arrangement, where the standby pump is only required in the event of a duty pump failure.
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The standby pump then runs for as long as needed to repair or replace the duty pump, at which point it is taken offline and returns to standby mode. The second approach is an alternating or intermittent arrangement, where at pre-arranged times pumps alternate between duty and standby modes, sharing demand time and evening out the running time between them. Engineers may argue in favour of
one or the other and, while both have advantages and disadvantages, gaining the most from a standby pump relies on selecting the best configuration and making use of test data to optimise maintenance procedures and reduce down time If using a duty/standby
configuration, it’s essential that regular
maintenance and testing is carried out on both pumps. A standby pump is unlikely to be in optimal working order if it has been standing idle for some period of time and is suddenly brought online, especially if the system fluid is likely to leave deposits of silt or sludge in the pipework or pump itself, or harden and cause blockages. If this is the case, leaving a standby pump idle for long periods is inadvisable and an alternating arrangement is preferable. Duty/standby configurations may also suffer from increased bearing wear, with surfaces becoming flattened when the pump is not turning.
A STRESSFUL START Turning to the alternating method, a major consideration is that start- up is the most stressful part of pump
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