How does a Graco electric pump or double diaphragm pump work?

The difference from an air-operated diaphragm pump is the center section of this pump as it uses an electric drive instead of compressed air. The center section of this pump is filled with pressurized air and is mechanically moved left/right by the motor so it pushes and pulls the diaphragm from left to right. This back-and-forth motion, forces liquid out of one chamber and into the outlet manifold, while filling the opposite fluid chamber via the inlet manifold. Upon changeover, the fluid section that was filled on the previous shift empties into the outlet manifold and the fills the opposite chamber via the inlet manifold. The smooth changeover allows for reduced pulsation at the outlet.

How does the electric diaphragm pump stall under pressure?

Important to know is that the Electric Graco pump don’t have a fixed connection to the center section. When the pressure at the outside of the center section is larger than the pressure inside the center section, the diaphragms will stand still without pressure building up. The center section will still turn left/right but the diaphragms won’t move until the outside pressure is lower than the pressure inside the center section.