Reading the Air Operated Double Diaphragm Pump Performance Curve

We at Antlia Pumps offer a variety of AODD pumps in our range. In this case, let’s consider AOD 40 in particular. This pump can transfer up to 140 liters per minute and produce 7 bars of pressure. The diaphragm pump can be used to pump acids, solvents, paints, lubricants & other fluids.

The above performance curve is for the AOD 40 model which shows required air pressure to pump a specific volume of liquid. It looks complicated; however, with a little help it’s easy to understand. Let’s understand the graph:

  • X-axis: The X-axis or the bottom horizontal side of the graph shows the discharge of liquid/fluid in liters per minute.
  • Y-axis: The Y-axis or the vertical line on the graph shows the air pressure used in bars on the left hand side in red, this is measured from 0 to 7.
  • Black Point: This is the reference point which shows the air consumption of the pump in both cubic meters per hour & standard cubic feet per minute (SCFM).

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

  • Follow the closest solid blue line up to the left until it meets on the Y-axis. That’s the inlet air pressure required. In this case it is 5 bars.
  • Vertically track down from the marked black point along the blue line until it intersects the horizontal X-axis originating from 60 LPM.
  • Initially, we need to find the inlet air pressure. Place the pointer on the 4 bar line on the Y-axis.
  • Let’s assume we require a volume of 60 litres per minute at 4 bar discharge pressure.
  • Finally, you can figure out the air consumption by tracing the pointer along the nearest blue line from the black point where the horizontal line from 4 bar and a vertical line from 60L/min intersect, up to the connected green box. In this case, to achieve 60 liters per minute at 4 bar discharge pressure you will require 5 bar inlet pressure at 14 scfm.

Looking at the performance curve of a pump you will understand what should be exactly expected of the equipment. It’s a great way to evaluate whether a pump will be the right fit.