Phase 1 air side: The air, through the opening of the distributor channels, passes into the left membrane which inflates. The shaft pulls the right membrane which deflates, conveying the excess air to the discharge.
Phase 1 fluid side: In the left chamber, the fluid is exiting from the delivery manifold under the pressure created by the membrane. The suction ball is closed and the delivery ball is open.
In the right chamber, a vacuum is being created (due to the deflation of the membrane's air) allowing the opening of the suction ball and the passage of the fluid through the suction manifold. The delivery ball is closed.

Phase 2 air side: Once the left membrane has finished charging, it begins to discharge. Other channels on the distributor then open, directing air into the right membrane which inflates.
Phase 2 fluid side: When the left membrane discharges, the left chamber fills with fluid. The suction ball opens due to the vacuum created, and the fluid passes through the suction manifold. In contrast, in the right chamber, the fluid is pushed into the delivery manifold, the suction ball is closed while the delivery ball is open.

With only two working phases and no idle period, the cycle of the double diaphragm pneumatic pump is complete and can begin again.