Centrifugal pumps are connected in series if the discharge of one pump is connected to the suction side of a second pump. Two similar pumps, in series, operate in the same manner as a two-stage centrifugal pump.

Each of the pumps is putting energy into the pumping fluid, so the resultant head is the sum of the individual heads.

Some things to consider when you connect pumps in series:

Both pumps must have the same width impeller or the difference in capacities (GPM or Cubic meters/hour.) could cause a cavitation problem if the first pump cannot supply enough liquid to the second pump.

Both pumps must run at the same speed (same reason).

Be sure the casing of the second pump is strong enough to resist the higher pressure. Higher strength material, ribbing, or extra bolting may be required.

The stuffing box of the second pump will see the discharge pressure of the first pump. You may need a high-pressure mechanical seal.

Be sure both pumps are filled with liquid during start-up and operation.

Start the second pump after the first pump is running.

PARALLEL OPERATION

Pumps are operated in parallel when two or more pumps are connected to a common discharge line, and share the same suction conditions.

Some things to consider when pumps are operated in parallel:

Both pumps must produce the same head this usually means they must be running at the same speed, with the same diameter impeller.

API 610, states that when pumps are run in parallel,

2012-07-26

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