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How Does an Air Operated Diaphragm Pump Work?

First let’s describe all the parts inside an air operated Diaphragm pump. The parts of a diaphragm pump include:

• Inlet and outlet where water comes in and out.
• Two liquid chambers connected by a shaft
• Two diaphragms
• 2 inlet balls and 2 out let balls
• Air valve

As air pressure hits the back of diaphragm A the suction process begins on diaphragm B. This creates a vacuum like force in chamber B allowing water to pass through the inlet ball valve. As the diaphragm B discharge stroke reaches its limit, air pressure is redirected to the back of diaphragm B, forcing the inlet ball on its sit and discharge ball off its sit. The process on chamber B occurs on the opposite chamber creating one full cycle.

How to Read an Air Operated Diaphragm Performance curve

Below is the Performance curve of the 3” (76mm) Heavy Duty Bolted Style Pump. Before you begin trying to make sense of this Diaphragm curve you must know the following data:

• Optimal flow rate
• Optimal discharge pressure
• Air pressure available at air inlet of the pump

On the left hand side of the chart we have the air inlet pressure in “PSI” and on the right hand side we have the air inlet pressure converted from “psi” to feet/meters. The bottom of the chart has the flow rate in gallons per minute. While the top has the flow rate in liters per minute.

How to Obtain the Discharge Pressure from a Diaphragm Performance Chart?

If 80 psi is available during air inlet and required discharge flow is 85 GPM. Follow the sloping downward blue line at 80 psi on the left side of the chart, until it hits 85 GPM. Then move back to the y axis horizontally and you get a discharge pressure of 60 psi. To find out the air inlet pressure, reverse the steps above.

For more technical information read our 3” (76mm) Heavy Duty Bolted Style Pump PDF.