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    • The air chamber is the chamber that houses the air which powers the diaphragms.
    • The air distribution system is the heart of the pump. The air distribution system is the mechanism that shifts the pump in order to create suction and discharge strokes.
  3. LOCK NUT (Outer Diaphragm Piston).
    • The outer diaphragm pistons provide a means to connect the diaphragms to the reciprocating common shaft and to seal the liquid side from the air side of the diaphragm.
  4. HOLDING PLATE (Inner Diaphragm Piston).
    • The inner piston is located on the air side of the pump and does not come into contact with the process fluid.
    • Eureel air-operated pumps use suction and discharge check valves to produce directional flow of process fluid in the liquid chamber. The check valve balls seal and release on the check valve seats allowing for discharge and suction of process fluid to occur.
    • The removable seats provide the ball valves a site to check.
    • Process fluid exits the pump from the discharge port located on the discharge manifold at the top of the pump.
    • The liquid chamber is filled with the process fluid during the suction stroke and is emptied during the discharge stroke. It is seperated from the compressed air by the diaphragm.
    • The diaphragm membrane provides for separation of the process fluid and the compressed air power source. To perfrom adequately, diaphragms should be of sufficient thickness and of appropriate material to prevent degradation or permeation in specific process fluid applications. Eureel offers a variety of diaphragm materials for your specific application requirements.
    • Process fluid enters the pump from the intake port located on the inlet manifold at the bottom of the pump.
AODD Pump parts breakdown

How do Eureel AODD pumps work?

The EUREEL diaphragm pump is an air-operated, positive displacement, self-priming pump. These drawings show the flow pattern through the pump upon its initial stroke. It is assumed the pump has no fluid in it prior to its initial stroke.

AODD Pump strokes: Right Stroke


The air valve directs pressurised air to the back side of diaphragm A. The compressed air is applied directly to the liquid column separated by elastomeric diaphragms. The diaphragm acts as a separation membrane between the compressed air and liquid, balancing the load and removing mechanical stress from the diaphragm. The compressed air moves the diaphragm away from the center block of the pump. The opposite diaphragm is pulled in by the shaft connected to the pressurized diaphragm. Diaphragm B is on its suction stroke; air behind the diaphragm has been forced out to the atmosphere through the exhaust port of the pump. The movement of diaphragm B toward the center block of the pump creates a vacuum within chamber B. Atmospheric pressure forces fluid into the inlet manifold forcing the inlet valve ball off its seat. Liquid is free to move past the inlet valve ball and fill the liquid chamber (see shaded area).

AODD Pump strokes: Mid-Stroke


When the pressurised diaphragm, diaphragm A, reaches the limit of its discharge stroke, the air valve redirects pressurised air to the back side of diaphragm B. The pressurised air forces diaphragm B away from the center block while pulling diaphragm A to the center block. Diaphragm B is now on its discharge stroke. Diaphragm B forces the inlet valve ball onto its seat due to the hydraulic forces developed in the liquid chamber and manifold of the pump. These same hydraulic forces lift the discharge valve ball off its seat, while the opposite discharge valve ball is forced onto its seat, forcing fluid to flow through the pump discharge. The movement of diaphragm A toward the center block of the pump creates a vacuum within liquid chamber A. Atmospheric pressure forces fluid into the inlet manifold of the pump. The inlet valve ball is forced off its seat allowing the fluid being pumped to fill the liquid chamber.

AODD Pump strokes: Left-Stroke


At completion of the stroke, the air valve again redirects air to the back side of diaphragm A, which starts diaphragm B on its exhaust stroke. As the pump reaches its original starting point, each diaphragm has gone through one exhaust and one discharge stroke. This constitutes one complete pumping cycle. The pump may take several cycles to completely prime depending on the conditions of the application.


The pumps supplied by Eureel are warranted for a period of two years from the date of sale to original purchaser. If a pump is proved, to Eureels’ satisfaction, to be defective within the warranty period, Eureel shall be liable for the repair or, at Eureels’ option, replacement. The pump shall be returned to Eureel, freight prepaid. Eureels’ obligation shall be confined to such repair or replacement and shall be further conditioned upon Eureel receiving written notice of any alleged defect within 5 working days after its discovery. Eureel assumes no responsibility for improper use of pumps or where pumps are used in excess of rated capacities and design functions, or under abnormal conditions. Warranty is void if the product or any part thereof has been tampered with, altered, or repaired by other than qualified service personnel. Any products, components or accessories that are not manufactured by Eureel and are supplied by other manufacturers are subject to their respective guarantees or warranties. Certain products will carry their own warranties.

Custom made pumps specially built to customers’ specifications and requirements are not subject to cancellation nor returnable for credit under any condition. Eureel reserves the right to modify or alter materials, dimensions, design and construction, when necessary, to improve performance.


We supply Air Operated Double Diaphragm Pumps and Accessories for any application in PP, PVDF, AL, CI and SS316

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