Figure 3 illustrates the hydraulic effects of operating a single pump versus two pumps in series, as well as illustrates the problem. It ran into both a common problem and a more unusual one. When two or more pumps are arranged in parallel their resulting performance curve is obtained by adding the pumps flow rates at the same head as indicated in the figure below. Two pumps set up with one pump as an installed spare. Thus, the first pump at capacity Q1 develops the same head H as the second pump … With pumps in parallel, the flow rates are additive with a common head. The flowrate Qt is split between the inlet into Q1 and Q2. Pump in Parallel. Centrifugal pumps in parallel are used to overcome larger volume flows than one pump can handle alone. In other words, pumps can run in parallel or separately, covering a wide range of expected flows. If you have a two-pump system, the first step is to determine how the system is designed: Two pumps set up to run individually and/or in parallel. Groups of low flow pumps and high flow pumps are often operated together in parallel to match variable system demand. Running two identical pumps in parallel can pose a number of problems, as one plant certainly discovered. Parallel pump installations, where two or more pumps take suction from a common manifold and discharge into a common header, are very common in many industries, including the Municipal Water and Wastewater markets. Each pump develops the same head H at the corresponding capacity.

Parallel operation, or parallel pumping, of two centrifugal pumps is a mode which allows pump operation to be controlled by starting or stopping one of the two pumps. Parallel pump installations, where two or more pumps take suction from a common manifold and discharge into a common header, are very common in many industries, including the … If two centrifugal pumps I and II are operated in parallel, the flow rate QI+II is the sum of the flow rates of …

This does not mean that pumps must have identical characteristics.

The key to running dissimilar pumps in parallel is to run the total system flow rate in a range that allows both pumps to run within a reasonable region on their pump curves to avoid issues due to excessive loads on the impeller, bearings, or seals. The plant had two parallel units that were identical in equipment but had some piping and layout differences (Figure 1). The primary concern when running centrifugal pumps together in parallel is that pumps share the load safely at lower flows. Pumps in Parallel - Flow Rate Added. Each pump normally operated at the intersection (2) of its head-capacity curve [Head(1)], producing about 800 gpm at 1,480 ft of head.