In fact, once you look closely at parallel pumping and how to apply it properly, you will find that you don’t need to use bigger in-line or base-mounted pumps as often because two smaller pumps in parallel will handle the job just as well. …

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. Centrifugal pumps in parallel are used to overcome larger volume flows than one pump can handle alone.

Parallel Pump Operation When pumps run in parallel they operate against the same discharge head. The head (and therefore flow) that each of the parallel pumps will operate at in a given system is then determined by the intersection between the system head-capacity curve with this “pump combination head-capacity curve”.

Operating Two Different Sized Pumps in Series When operating in Series, the size difference of the 2 Pumps means that Pump-B can be a larger pump producing higher Heads, or can even be a multi-stage pump producing much higher Heads. But it is essential that the Flowrates of both Pump-B and Pump-A must be the same.

I think you can run your pumps in parallel just fine. However, you may need to put a one way value in line with each of them to keep them from fighting one another and avoid pack pressure. Maybe you won’t need the values but running them in parallel should work just fine.

For identical pumps with similar functions, if the pumps arranged in series, the total head is increased without a change to maximum discharge. On the other hand, for pumps arranged in parallel to one another, the discharge is increased without any changes to maximum head.

Multistage pumps are an economic means of covering the higher pressure ranges of pump series selection charts. Further advantages are that multistage pumps can easily be tapped downstream of a stage or that dummy stages can be fitted for future pressure increases.

Positive Displacement Pumps This allows for flexibility in system layout and eliminates the need for suction priming systems. Air operated diaphragm pumps self-prime by creating a pressure differential in the diaphragm chamber – which draws in air and pulls the fluid into the suction port.

The apparatus comprises two identical centrifugal pumps,together with two bearing-mounted motors driving each pump independently. The pumps draw water from the clear acrylic reservoir. The water travels through a series of valves to be delivered to a flow measurement device.

Putting your centrifugal pumps in series, or connected along a single line, will let you add the head from each together and meet your high head, low flow system requirements. This is because the fluid pressure increases as the continuous flow passes through each pump, much like how a multi-stage pump works.

A centrifugal pump is a rotodynamic pump that uses a rotating impeller to increase the pressure and flow rate of a fluid. Centrifugal pumps are the most common type of pump used to move liquids through a piping system.

Since each pump generates a head H corresponding to a flow Q, when connected in series, the total head developed is Ht = H1 + H2, where H1, H2 are the heads developed by the pump in series at the common flow rate Q. With pumps in parallel, the flow rates are additive with a common head.

Often, a good system design is to have pumps in parallel because they can provide flexibility to match the flow to the load. If the system is designed for parallel pumps, determine which pump is the stronger one by running one at a time and measuring the head at various flows.

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. At point 4, one other pump of the same characteristics can be started due to the shut-off head (H0).

The affinity laws can usually be used up to an impeller trim of 95%, as accepted by the Hydraulic Institute. However, as the impeller is trimmed to lower diameters, a mismatch develops between an impeller and casing flow areas, which makes the pump less efficient.

Series operation When centrifugal pumps are connected in a series, the discharge of one unit leads to the suction of the next. In other words, two similar centrifugal pumps in a series operate much like a twostage pump. Each pump imparts energy to the liquid being pumped.

Please see the following image where there is comparison between positive displacement pumps (Reciprocating pumps are type of PDP) and Dynamic pumps (Centrifugal pumps). It is clear that PDP are used when we need high outlet pressure and dynamic pumps are used when we need high discharge.

Radial impellers are generally used in low flow high head designs, while Axial impellers are used in high flow low head designs. Pumps of higher specific speeds develop head partly by centrifugal force and partly by axial force.

Explanation Using Pump Characteristics >The discharge valve of the pump has to be closed during startup. This is maintained so, inorder to prevent sudden load on the power system, if the valve is open. If you look at the characteristics of the pump, the power required ,increases with flow rate.

If the discharge valve is closed and there is no other flow path available to the pump, the impeller will churn the same volume of water as it rotates in the pump casing. The vapor can interrupt the cooling flow to the pump’s packing and bearings, causing excessive wear and heat.

The pump is started if both valves, inlet and outlet are closed, the pump will pump nothing out, the pump will get really hot very fast, such as a water pump in a boat motor, if there is no water to pump in a boat motor to cool down the motor, because the suction valve is closed, the centrifugal pump will get hot, the …

IT IS A NORMAL PRACTICE TO START THE CENTRIFUGAL PUMP WITH ITS DISCHARGE VALVE CLOSED. THE REASON BEHIND THIS CAN BE FOUND OUT BY LOOKING AT THE CHARACTERISTIC CURVE OF CENTRIFUGAL PUMP. WHEN THE DISCHARGE VALVE IS CLOSED, THAT TIME QUANTITY DISCHARGED IS ZERO, AND AT THAT TIME POWER CONSUMED IS LEAST.

There are three basic types of pumps: positive-displacement, centrifugal and axial-flow pumps.

Efficiency & Performance In general, a reciprocating pump is more efficient than a centrifugal pump. Reciprocating machines are generally applied on low-flow/high-head service. Centrifugal pumps can have efficiencies as low as 40 percent on low-flow/high-head service.

Before you can select a pump that will fit your needs, you must know four things: 1) the total head or pressure against which it must operate, 2) the desired flow rate, 3) the suction lift, and 4) characteristics of the fluid.

Peristaltic pumps do not require priming. There is no requirement for continuous fluid flow at the pump’s inlet. Air or offgas being present within the flexible tube, are also pumped together with the fluid. The presence of air in the pump, can affect the pump’s performance, however.

When it comes to pumping types, there are two main types that are pumps for domestic and agricultural water. These two types are further divided into categories, which include: water pump, irrigation pump, centrifugal pump, submersible pumps, etc. We use domestic to draw water for our domestic purposes.

Pump sizing can be accomplished in six steps, as follows:

1. Find the total dynamic head, which is a function of the four key components of a pumping system, such as the one shown in Figure 1.
2. Correct for the viscosity of the fluid being pumped, since pump charts and data are given for water with a viscosity of 1 cP.

Example – Horsepower Required to Pump Water