The Components of An AODD Pump and How They Operate

Did you know that one of the simplest technologies used in factories and plants is also one of the most potent workhorses in the industry? That’s right – it’s the AODD pumps!

Air-operated double-diaphragm (AODD) pumps are widely used in factories and plants due to their resilience and versatility in handling harsh fluids in the most challenging environments.

With a minimal number of parts, AODD pumps demonstrate exceptional reliability while requiring minimal maintenance, making them a popular choice across various industries, including mining and food and beverage production. In addition, AODD pumps remain a top contender in industrial workhorses, owing to their impressive performance and simplicity.

Have you ever wondered how a seemingly simple piece of machinery can keep production running smoothly at top speed? The secret lies in the carefully designed AODD pump components.

How Each Component of Diaphragm Pumps Is Essential to Its Operation

Understanding the basics of AODD industrial pumps can give you the power to make informed decisions to help your pump perform at its best in any application. Continue reading to find out more about each detailed pump component.

AODD Fluid Side Component

Fluid Suction and Discharge Manifold

  • It serves as a seal and a flow path for the fluid.
  • The manifold is secured or fixed to the outer chambers to create a closure and flow path.
  • Valve or seat seals make a leak-free closure between the manifolds and the external fluid chamber.
  • The valve/seat seals also house the valve balls in the ball cages within the manifolds.
  • The manifold is carefully engineered to withstand harsh conditions and ensure smooth, fluid flow.

The fluid suction and discharge manifold are essential for reliable Industrial pump performance.

AODD pump Outer Fluid Chamber

  • The seats or seat seals attach and close at the suction and discharge manifolds.
  • The outer fluid chamber is also sealed between the inner chamber and the air chamber with the bead of the diaphragm.
  • The outer fluid chamber produces a space that permits the reciprocating diaphragms to pull in and expel fluid on each side, thereby generating the pumping motion.
  • The design of the outer fluid chamber is critical to the pump’s overall performance and reliability.


The Function of Diaphragms

The diaphragms serve as a partition that isolates the fluid section of the pump from the air section.

In typical configurations, the diaphragms ensure airtightness at two locations:

  • At the central aperture of the diaphragm by fastening the internal and external diaphragm plates to the primary shaft, securing the diaphragm. A tight seal is produced when the correct torque is applied.
  • Another sealing mechanism of the diaphragms occurs at the external perimeter, commonly at the molded-in sealing bead or via the sealing grooves on the interior air chamber and the exterior fluid chamber. This seal is established by compressing the diaphragm by tightening the bolts on the outer section (for bolted pumps) or using large clamp band assemblies (for clamp-style pumps).
  • Bonded PTFE diaphragm designs may incorporate inner and outer plates, making them center-hole accessible. This feature eliminates the need for separate containers and enables hand tightening onto the threaded diaphragm shaft. As a result, this design is often favored for hazardous chemical applications.
  • When air pressure is applied behind the diaphragm on the air side of the pump, the diaphragm functions as a dynamic component and flex. The regulated air pressure applies force on the side of the diaphragms exposed to air, which is then transferred to the liquid being pumped in an equivalent amount.
  • Manufacturers produce diaphragms in various materials and designs to fulfill specific application needs, including chemical compatibility, temperature, abrasion resistance, and certification requirements. Therefore, it is advisable to seek further information from the manufacturer.

The Function of Inner/Outer Diaphragm Plates

  • The inner and outer diaphragm plates perform in tandem with the diaphragms to isolate the fluid side of the pump from the air side.
  • The plates are threaded to the primary shaft/diaphragm rod, pressing the diaphragms and forming an airtight seal for air and fluid.
  • Furthermore, the diaphragm plates support the diaphragms as the shaft moves back and forth, creating a suction on the fluid, drawing it into the pump’s fluid chambers, and expelling it.

Clamp Assemblies or Bolts and Their Function

  • Either clamp assemblies or bolts are utilized to assemble the pump components, depending on whether the pump is of clamped style or bolted construction.
  • Together with the diaphragms and valve seats, these elements establish a seal containing the fluid in the pump and segregate the air from the fluid side.

AODD Air Side Components


The Main Shaft/Diaphragm Connecting Rod

  • It connects the diaphragm assemblies.
  • The diaphragm assemblies include the inner and outer plates and diaphragms.
  • Shafts can be either male or female-threaded.
  • The outer plates are attached to the shafts through the threads.

The Inner Chamber/Air Chamber

  • It holds a seal with the diaphragms while introducing compressed air into each side of the chamber.
  • The compressed air is alternated between each side of the section, exerting pressure on the backside of the diaphragms.
  • The pressure exerted on the rear of the diaphragms is then transferred to the fluid.

The Air Valve

  • It directs compressed air into one of the two chambers to shift the diaphragm/connecting rod assembly.
  • While the air is directed to one chamber, the air valve ports air from the opposite chamber.
  • The ported air from the opposite chamber is exhausted to the atmosphere through the intermediate/center block exhaust port.

The Intermediate/Center Block

  • It typically guides the central shaft/diaphragm rod with seals and bushings.
  • The primary or pilot shaft (depending on the manufacturer’s design) delivers alternating pressure to the air valve.
  • This alternating pressure shifts the main valve spool, which in turn causes the pump to reciprocate and create the pumping action.
  • In most cases, the air is exhausted from the intermediate block via the exhaust port and released through the air exhaust muffler.

The Air Exhaust Muffler

  • It helps minimize the noise produced by the exhaustive air from the pump.
  • Various types, materials, and sizes of mufflers are available.
  • The muffler can be detached so that the exhaust can be ported away from the pump, submerging the pump.
  • Alternatively, the muffler can be removed to exhaust the air to a safe location or outside, reducing further noise in the work environment.


How AODD Industrial Pumps Works?

Having acquainted yourself with the fundamental elements of an Air-Operated Double Diaphragm (AODD) pump, we shall now delve into its operational mechanism. Presented below is a dissected AODD unit, which exemplifies the functionality of the primary pump components.

The Suction Cycle

The compressed air enters the left inner chamber, resulting in the formation of suction by the diaphragm on the opposite side. This suction lifts the lower valve ball, enabling fluid intake through the inlet. Meanwhile, the left fluid chamber is concurrently engaged in the “discharge” cycle.

Discharge Cycle

The right inner chamber is filled with compressed air, leading to the opening of the upper valve ball and the consequent fluid discharge. At the same time, the left section is in the “suction” cycle.

Key Factors to Consider for Pump Components

When opting for an Industrial pump suitable for a particular application, specific pump components can significantly impact overall performance and mean time between failures.

Valve balls

Valve balls constitute a crucial element of the pumping system. For pumping thick, viscous liquids, heavy or weighted valve balls are recommended. This is because the force of gravity enables the heavy valve balls to cut through the thick product and seat faster, enhancing the pump’s effectiveness in handling such fluids. In addition, valve balls made of materials like PTFE or stainless steel are considerably heavier than those made of other substances.

Valve Seats

The selection of appropriate valve seats is critical for optimizing the performance of the industrial pumping system. When handling abrasive fluids, opting for valve seats composed of abrasion-resistant materials is advisable. For instance, when pumping abrasive ceramic slips, replacing rubber valve seats with stainless steel is recommended to minimize the wear and tear associated with abrasive applications.

Materials Used in the Air Side of the Pump

The fluid being pumped does not solely come into contact with the wetted side of the pump. The air side of the unit is also likely to be exposed to the fluid, either through the surrounding environment or in the event of diaphragm failure. In such cases, the air side (air valve, center block, air chambers, etc.) must be composed of materials that are chemically compatible with the fluid. This is essential as the pump may come into contact with fumes or be splashed with chemicals from the process.

Considering material compatibility with the fluid being pumped during a diaphragm failure is also crucial. Such failure can result in the liquid coming into contact with the air side of the pump, causing damage if the materials used in the air side are not chemically compatible with the fluid. Therefore, it is imperative to ensure that the air side components are made of suitable materials to withstand exposure to the pumped fluid during regular operation and in case of unforeseen circumstances like diaphragm failure.

Employing a chemically compatible material with the pump’s air and wetted side can significantly enhance its longevity and performance. In most scenarios, the additional upfront cost of certain air-side materials (like stainless steel) that offer chemical compatibility is justifiable. Besides, polypropylene and coated metal air side components can also be advantageous alternatives to consider.

Choosing an Industrial AODD Pump

JEE Pumps can effectively handle various chemicals, flow rates, and viscosities, making them suitable for multiple industries.

While diaphragm pumps are relatively easy to comprehend, acquiring knowledge about specific components can facilitate the selection of the optimal pump for a given application.

Selecting a reliable pumping partner is a crucial decision. With nearly 30 years of experience, JEE Pumps has been a leading manufacturer of industrial pumps, including AODD pumps catering to various industries’ unique demands worldwide.

Whether you are searching for a new pump or require replacement parts and accessories, JEE Pumps’ established products and proficiency can be relied upon.



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