To determine compressed air requirements and proper size for a Yamada air-operated double diaphragm pump, two elements of information are required:

1. Required Flow Rate (GPM)
2. Total Dynamic Head (TDH)

As an example in the above curve, consider an NDP-40 Series pump performance curve with rubber diaphragms, pumping 80 GPM at 50-ft TDH.

Point A (O) on the performance curve is where the desired Flow Rate (GPM) and Total Dynamic Head (TDH) points intersect. This point determines compressed air requirements for the particular pump.

At performance point A (O), the pump will require approximately 75 PSI air inlet pressure. To arrive at this figure, follow the solid blue curve (-) to the left to read the air pressure rating in PSI.

By looking at the nearest red curve (-), it is determined the pump will require approximately 80 SCFM (Standard Cubic Feet per Minute) of air volume.