Did You Know?

Jun 15, 2026      Admin Michael

How a diaphragm pump works (Air-Operated Double Diaphragm / AODD)
A diaphragm pump moves liquid by flexing one or two elastomer diaphragms back and forth, creating alternating suction and discharge strokes. In a Yamada AODD pump, compressed air provides the driving force.

Core parts involved

• Two diaphragms connected by a single shaft (they move together)
• Two pumping chambers (one on each side)
• Four check valves (inlet and outlet checks) that enforce one-way flow
• Air distribution valve (air valve) that alternates air to each diaphragm

Step-by-step cycle (what’s happening inside)

1. Air to Chamber A (Discharge stroke on A)
   The air valve sends compressed air behind Diaphragm A, pushing it inward.

   • Liquid in Chamber A is pushed out through the outlet check valve.
   • The inlet check on that side closes to prevent backflow.

2. Simultaneous suction on Chamber B
   Because the diaphragms are linked, Diaphragm B moves outward at the same time, enlarging Chamber B.

   • This creates vacuum (suction), pulling liquid in through the inlet check valve.
   • The outlet check on that side stays closed.

3. Air valve shifts (automatic) At end-of-stroke, the air valve “trips” and redirects air to the opposite side.

4. Roles reverse Chamber B becomes the discharge side, and Chamber A becomes the suction side.
   This repeats continuously, producing flow.

Why check valves matter

• They open/close based on pressure differences created by diaphragm movement.
• They prevent reverse flow and ensure the pump “self-primes” and moves fluid in one direction.

Key advantages of Yamada AODD diaphragm pumps

• Self-priming, handles intermittent suction lift
• Dry-run capable (no mechanical seal to burn up)
• Can pass solids/shear-sensitive fluids (application dependent)
• Variable flow by adjusting air pressure/air volume
• Yamada’s non-lube air valve design supports reliability and reduced icing/stalling risk