Critical systems should always be equipped with more than one pump. Choosing between the installation of one or more backup pumps depends on the costs of the installation and

  • how critical the operation of the system is - a water supply system for a hospital is more critical than a chilled water cooling systems for homes.
  • the delivery and installation time of a new pump.

If two or more pumps are used, the operation between the pumps should be systematically altered to achieve equal wear.
[h=Alternatives for Alternating Pumps]3[/h] Pumps can be systematically altered by

  • manual alteration - where the operator selects the lead pump and the sequence of the lag pumps.
  • duty alternation - where the lead pump change every time the pump or system is stopped.
  • timed alternation - where the lead pump is switched by a timer or clock.
  • equal run time - where the lead pump is switched to achieve the same operating time for each pump.

Note! Running an automatic system for equalizing the wear of the pumps

  • has the advantage of extending the time before repair and reinvestments.
  • has the disadvantage that all pumps may wear out on at the same time - reducing the operation safety for the whole system.