Question: What Is Pump Curve?

What is pump run out?

Pump runout, or runout flow, is the maximum flowrate that can be developed by a pump.

The runout conditions correspond to a very small pump head, while the flow rate is maximal.

The performance curve (published by pump manufacturer) is typically cut off at some point beyond the pump’s allowable operating range (AOR)..

What does it mean when a pump is cavitating?

Cavitation in pumps is the rapid creation and subsequent collapse of air bubbles in a fluid. … In many cases, the force of cavitation is strong enough to pit metal components of the pump, like the impeller, and damage pump seals.

How do you read a centrifugal pump curve?

The Pump curve shows the Flowrate range on the horizontal scale. As standard the Flowrate is from zero flow to 20% past the Best Efficiency Flow. The first point on the curve at zero flow is referred to as “Shut Off” and the last point at maximum flow is “Run Out”.

How do you interpret NPSH curve?

Pump curves are essentially data about a given pump’s ability to produce flow against certain head. When you’re reading a curve, the pump’s flow rate will be on the top and bottom and its height to push is on the sides.

Why is NPSH important?

NPSH or Net Positive Suction Head is a very important part of a pumping system. The systems NPSHA must be higher than the pump’s NPSHR in order for proper pump performance and to eliminate the risk of cavitation, which can damage a pump in short order and shut down operations that depend on that pump.

What does NPSH mean?

Net Positive Suction HeadNPSH stands for Net Positive Suction Head and is a measure of the pressure experienced by a fluid on the suction side of a centrifugal pump.

How do you determine what size pump you need?

The steps to follow to select a centrifugal pump are:Determine the flow rate. To size and select a centrifugal pump, first determine the flow rate. … Determine the static head. … Determine the friction head. … Calculate the total head. … Select the pump.

How do I choose a pump size?

Pump sizing can be accomplished in six steps, as follows: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.Correct for the viscosity of the fluid being pumped, since pump charts and data are given for water with a viscosity of 1 cP.More items…•

How do you find the pump curve?

To find the pump performance curve you need, simply type the pump name into the “Product” search field and select the product and model you want. This will then provide the right pump curve as well as additional pump information.

What is pump size?

Pump sizing involves matching the flow and pressure rating of a pump with the flowrate and pressure required for the process. The mass flowrate of the system is established on the process flow diagram by the mass balance.

What happens when a pump runs off its curve?

If a pump is running out on the end of the curve it can cause cavitation inside the pump and result in premature wear of the impeller and bearings of the motor. It can also cause the motor to over amp and prematurely fail.

What does a pump curve tell you?

A pump performance curve indicates how a pump will perform in regards to pressure head and flow. A curve is defined for a specific operating speed (rpm) and a specific inlet/outlet diameter. … The curve also shows the shut off head or the head that the pump would generate if operating against a closed valve.

How do you read a flow curve?

When reading left to right, flow is increasing. And the reverse is true when reading right to left. Depending on whether flow is increasing or decreasing, the curve will be slightly different. Outlet pressure will not follow the same “droop line,” nor end at the original set pressure.

How do you select a curve from a pump?

Look at the left side of the curve and you will see a label HEAD – FT and numbers starting with 0 and increasing as you move up the chart. This is the pressure that the pump is capable of producing, measured in feet of head (not PSI!) The bottom of the curve is labeled US GPM. This is the flow that the pump produces.

What is NPSH pump curve?

The NPSH curve displays the minimum required inlet pressure (expressed in m) allowing the pump to pump in accordance with the performance curve and in order to prevent evaporation of the pumped fluid so as to avoid cavitation inside the pump.

How do you calculate NPSH?

Explanation: To calculate NPSH Available, take the source pressure , add the atmospheric pressure , subtract the losses from friction within the pipeline and subtract the vapor pressure of the fluid . The result equals the NPSHA (or Net Positive Suction Head Available) of your system.

What is NPSH required?

NPSH Required (NPSHR): The minimum pressure required at the suction port of the pump to keep the pump from cavitating. … NPSHA MUST be greater than NPSHR for the pump system to operate without cavitating. Put another way, you must have more suction side pressure available than the pump requires.