Critical systems must always be equipped with more than one pump. The choice between installing one or more backup pumps depends on installation costs and
- how critical is system operation – a water supply system for a hospital is more critical than a chilled water cooling system for a home
- the delivery and installation time of a new pump
If two or more pumps are used, operation between pumps must be alternated systematically to obtain equal wear.
Alternatives to Alternating Pumps
Pumps can be systematically switched by
- manual toggle – where the operator selects the main pump and sequence of lag pumps
- duty switching – where the main pump switches every time the pump or system is stopped
- timed toggle – where the main pump is triggered by a timer or clock
- equal run time – where the main pump is switched to achieve the same run time for each pump
Observation! Running an automatic system to equalize pump wear
- has the advantage of extending the time before repairs and reinvestments
- has the disadvantage that all pumps can wear out at the same time – reducing operating safety for the entire system
Source: https://www.engineeringtoolbox.com/alternating-pumps-d_667.html
