Reading an Air Operated Double Diaphragm Pump Performance Curve

In our previous posts we talked about how an air operated double diaphragm (AODD) pump works, and the advantages of installing this type of pump. In this blog post we’re looking specifically at the performance of the air operated double diaphragm pumps offered by Global Pumps.

How can you know a pump is the right fit for your needs if you don’t know how it will perform under different circumstances? That’s where the performance curve comes in.

The Verderair Air Operated Diaphragm Pump Performance Curve

At Global Pumps, we offer a number of pumps in the Verderair range. In our case study, let’s look at one model in particular - the VA40. This pump can transport up to 397 litres per minute and produce up to 8.4 bars of pressure. This pump can be used to pump oils, solvents, chemicals, and lubricants, and other fluids. 

Looking at the performance curve of a pump will tell you exactly what to expect from your equipment. It’s a great way to assess whether a pump will be the right fit for you.

Air Operated Diaphragm Pump Curve


The performance curve above is for the Verderair VA40, and shows how much air pressure is required to pump a specific volume of liquid (there are correction charts available for viscous fluids). It looks complicated; however, with a little help it’s easy to get a hang of - we’ll show you!

Let’s break down everything on the graph:

    • Y-axis: The Y- Axis or the vertical side of the graph shows the air pressure you are using in bar on the left hand side, this is measured from 0 to 10. On the right hands side of the graph you will see another vertical line where air pressure is measured in psi. This is also the discharge pressure of your pump. 
    • X-axis: The X-axis or the bottom horizontal black line shows the volume of fluid being pumped. This goes from 0 up to 500 litres or 130 gallons per minute.
    • Orange Boxes: These contain the air consumption rate of your pump in both cubic metres per minute or standard cubic feet per minute (SCFM). You can see our calculator here to covert cubic metres per minute to CFM.

The performance curve allows you to calculate the air pressure required to move a specific volume of fluid. For example:

  • Then, follow the closest solid blue line up to the left until it terminates on the Y-axis. That’s your inlet air pressure required. In this case it is 7 bars.
  • Track your finger across the line until it intersects with the vertical line stemming up from 200 litres per minute on the X-axis.
  • First, we need to find your inlet pressure. Place your finger on the 4 bar line on the Y-axis.
  • Let’s say you require a volume of 200 litres per minute at 4 bar discharge pressure.
  • Finally, you can figure out the air consumption by tracing your finger along the nearest blue dotted line from the point where the horizontal line from 4 bar and vertical line from 200L/min intersect, up to the connected orange box. In this case, to achieve 200 litres  per minute at 4 bar discharge pressure you will require 7 bar inlet pressure at 60scfm.


The Power of Performance Curves

With this knowledge in hand, you can use any performance chart to work out how your pump should perform under specific circumstances. 

Need Advice?

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Contact one of our trained staff members who’ll be happy to answer any of your questions.

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Tags: Verderair, Air operated diaphragm pumps, Selection


Guide to Selecting the Best Pump

If you need some guidance on how to select the right pump then you’re not alone! There’s such a wide range of pumps in Australia, from centrifugal pumps to hose pumps to diaphragm pumps. The options available to you can make it a difficult choice, so we’ve created this special guide to help step you through the process of selecting the ideal pump for your requirements.


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