What is a Diaphragm Pump

What Is a Diaphragm Pump? AODD Pump Operation, Uses & Benefits

What Is a Diaphragm Pump?

A diaphragm pump is a positive displacement pump that uses a flexible diaphragm to move liquid, slurry, powder, or other process materials through a pump chamber. Instead of using a rotating impeller, gear, or mechanical seal, a diaphragm pump uses reciprocating motion to draw fluid in through one side of the pump and push it out through the other.

One of the most common industrial designs is the air-operated double diaphragm pump, often called an AODD pump. Yamada air-operated double diaphragm pumps are used across a wide range of industries because they can handle many difficult-to-pump materials, including chemicals, coatings, oils, slurries, wastewater, adhesives, food-grade products, powders, and other challenging fluids.

If you need a pump that is flexible, self-priming, portable, and capable of handling tough fluids, a diaphragm pump may be one of the best options for your application.

How Does a Diaphragm Pump Work?

A diaphragm pump works by moving a flexible membrane, or diaphragm, back and forth inside a pump chamber. This motion changes the volume inside the chamber, creating suction on one stroke and discharge pressure on the next.

In a typical double diaphragm pump:

One diaphragm moves away from the liquid chamber, creating suction.
Fluid is drawn into the pump through an inlet check valve.
The opposite diaphragm moves toward its liquid chamber, pushing fluid out through the discharge check valve.
The air valve shifts, reversing the motion.
The process repeats continuously, creating steady positive displacement flow.

The diaphragm separates the fluid being pumped from the air side of the pump. This design helps protect the drive mechanism from the pumped material and eliminates the need for a mechanical seal.

For a closer look at the component itself, see What Is a Diaphragm?

Diagram explaining what a diaphragm pump is and how an air-operated double diaphragm pump moves fluid through inlet, outlet, check valves and diaphragms.

Common Diaphragm Pump Applications

What Is an Air-Operated Double Diaphragm Pump?

An air-operated double diaphragm pump, or AODD pump, is a diaphragm pump powered by compressed air. Instead of an electric motor, compressed air drives two diaphragms back and forth. As one diaphragm draws fluid into the pump, the other diaphragm discharges fluid out of the pump.

This design makes AODD pumps highly versatile for industrial fluid transfer. They are commonly used when the fluid is abrasive, corrosive, viscous, shear-sensitive, flammable, or difficult for other pump types to handle.

Yamada NDP Series air-powered double diaphragm pumps are designed for industrial fluid handling applications where reliability, material compatibility, and uptime matter.

Why Are Diaphragm Pumps Used?

Diaphragm pumps are used because they solve many common fluid-transfer problems. They are especially helpful when a process requires a pump that can handle difficult materials without relying on close-fitting rotating parts or mechanical seals.

Common reasons to use a diaphragm pump include:

The fluid contains solids or suspended particles
The material is abrasive, corrosive, or chemically aggressive
The fluid is thick, sticky, or viscous
The application requires self-priming
The pump may need to run intermittently
The discharge line may occasionally close
The pump needs to be portable
The application needs simple installation
The process requires a pump with no mechanical seal

To learn more about the benefits of this pump style, visit Advantages of Diaphragm Pumps.

Key Advantages of Air-Operated Diaphragm Pumps

Self-Priming Operation

AODD pumps are capable of self-priming, which means they can evacuate air from the suction line and begin drawing fluid into the pump. This is useful when pumping from drums, totes, tanks, sumps, pits, or other sources located below the pump.

Learn more about this capability here: What Is Self-Priming?

No Mechanical Seal

Many pump failures are related to mechanical seals, especially when handling abrasive, dirty, or chemically aggressive fluids. Diaphragm pumps do not require a mechanical seal. The diaphragm acts as a barrier between the pumped fluid and the air side of the pump, helping reduce potential leak points and maintenance concerns.

Handles a Wide Range of Fluids

Diaphragm pumps can handle many different materials, from thin solvents to viscous fluids and slurries. Depending on pump configuration and material selection, Yamada diaphragm pumps can be used for chemical transfer, paint and coatings, wastewater and sludge transfer, mining applications, battery manufacturing and EV battery materials, and many other industrial applications.

Deadhead Capable

If the discharge line is closed, an air-operated diaphragm pump can stop against pressure and resume operation once the line opens again. This makes AODD pumps useful in applications where flow may be restricted or stopped during normal operation.

Portable and Easy to Install

Because AODD pumps are powered by compressed air, they can be installed as part of a fixed system or used as portable transfer pumps. They are often selected for maintenance, emergency transfer, drum unloading, tote unloading, sump transfer, and general plant utility pumping.

Adjustable Flow and Pressure

The flow rate and discharge pressure of an AODD pump can be adjusted by controlling the air supply and discharge conditions. This allows one pump to serve a range of operating requirements within its performance limits.

For help understanding flow rate, air pressure, and total dynamic head, see Understanding Performance Curves.

What Fluids Can a Diaphragm Pump Handle?

Diaphragm pumps are used to transfer a wide variety of fluids and process materials. Common examples include:

Water and wastewater
Sludge and slurry
Acids and caustics
Solvents
Oils and lubricants
Paints and coatings
Inks
Adhesives and sealants
Resins
Food-grade products
Cosmetics and personal care products
Pharmaceutical support fluids
Ceramic slip and glaze
Battery material slurries
Mining slurries
Powders and bulk solids in specialty applications

Yamada offers multiple pump body materials, diaphragm materials, and specialty configurations to help match the pump to the fluid, temperature, pressure, and application requirements.

Common Diaphragm Pump Applications

Diaphragm pumps are used in many industries because they can handle difficult fluids and changing operating conditions. Common Yamada application areas include:

View more industries on the Yamada Applications page.

Diaphragm Pump Materials

Material selection is one of the most important parts of choosing the right diaphragm pump. The pump body, diaphragm, valve balls, valve seats, seals, and other wetted components must be compatible with the fluid being pumped.

Depending on the application, Yamada pump materials may include:

Aluminum
Stainless steel
Cast iron
Polypropylene
PVDF/Kynar^®
PTFE
Buna-N
EPDM
Santoprene^®
Hytrel^®
Neoprene
Viton^®
Other diaphragm and elastomer options

The best material choice depends on the fluid, temperature, abrasiveness, solids content, chemical compatibility, and operating conditions. For more detail on diaphragm material options, visit What Is a Diaphragm?

Diaphragm Pumps vs. Centrifugal Pumps

A centrifugal pump uses a rotating impeller to add velocity to a liquid. This works well for many clean, low-viscosity fluids, but it may not be the best choice for abrasive, viscous, corrosive, or solids-laden fluids.

A diaphragm pump is a positive displacement pump. It physically moves a set volume of fluid with each stroke. This makes diaphragm pumps a strong option when the application involves:

Variable flow conditions
Changing viscosity
Solids or suspended particles
Abrasive fluids
Corrosive chemicals
Suction lift requirements
Intermittent operation
Portable transfer needs

For clean water at high continuous flow, a centrifugal pump may be appropriate. For difficult fluids, chemical transfer, slurry transfer, and plant utility pumping, an AODD pump may provide better flexibility.

Diaphragm Pumps vs. Peristaltic Pumps

Both diaphragm pumps and peristaltic pumps are positive displacement pumps, but they operate differently. A peristaltic pump squeezes fluid through a hose or tube. A diaphragm pump uses diaphragms and check valves to draw fluid into and discharge fluid out of the pump chamber.

AODD pumps are often used where higher transfer flow, portability, air-powered operation, solids handling, and material flexibility are important. Peristaltic pumps may be selected when the fluid must remain contained within a hose path or when very low-shear tube-based pumping is required.

The best choice depends on the fluid, required flow rate, discharge pressure, suction conditions, and maintenance expectations.

What Is a Double Diaphragm Pump?

A double diaphragm pump uses two diaphragms connected by a common shaft. As one diaphragm moves in a suction stroke, the other moves in a discharge stroke. This paired movement helps create a continuous pumping cycle.

In an air-operated double diaphragm pump, compressed air alternates between the two air chambers. The air valve controls this shifting action. Yamada’s Patented Air Valve is designed for reliable, non-lubricated operation and is incorporated into Yamada air-powered double diaphragm pumps.

What Is a Membrane Pump?

A membrane pump is another name for a diaphragm pump. The terms are often used interchangeably because the diaphragm is a flexible membrane that moves back and forth to create pumping action.

In industrial fluid handling, the terms “diaphragm pump,” “double diaphragm pump,” “air-operated diaphragm pump,” “air-powered diaphragm pump,” and “AODD pump” are commonly used when referring to this style of pump.

When Should You Use a Diaphragm Pump?

A diaphragm pump is often a good choice when the fluid or application is too difficult for a standard pump. Consider a diaphragm pump when you need to transfer:

Chemicals
Corrosive liquids
Abrasive fluids
Fluids with suspended solids
High-viscosity materials
Slurries
Oils
Paints
Coatings
Adhesives
Wastewater
Sludge
Food-grade materials
Specialty process fluids

A diaphragm pump may also be a strong choice when you need self-priming, deadhead capability, portability, simple installation, or a pump with no mechanical seal.

Choosing the Right Diaphragm Pump

Choosing the correct diaphragm pump requires more than knowing the fluid name. To select the right pump, consider:

Fluid being pumped
Flow rate required
Discharge pressure
Suction lift
Total dynamic head
Fluid viscosity
Solids size and concentration
Chemical compatibility
Temperature
Abrasiveness
Required pump materials
Diaphragm material
Valve ball and seat material
Port size
Air supply pressure and volume
Continuous or intermittent duty
Portable or fixed installation

Yamada offers a broad range of NDP Series pumps, high-purity pumps, and specialty diaphragm pumps for many different fluid-transfer requirements.

Why Choose a Yamada Diaphragm Pump?

Yamada has built its reputation on reliable air-operated double diaphragm pump technology. Yamada pumps are designed for demanding industrial environments where uptime, durability, and application support matter.

Yamada diaphragm pumps are known for:

Air-powered operation
Self-priming capability
No mechanical seals
Material options for many fluids
Wide range of pump sizes
Broad application flexibility
Industrial-duty construction
Reliable air valve design
Support for chemical, slurry, oil, coating, food-grade, wastewater, and specialty applications

Explore the full Yamada NDP Series or contact Yamada for help selecting the right pump.

Frequently Asked Questions About Diaphragm Pumps

What is a diaphragm pump used for?

A diaphragm pump is used to transfer fluids, slurries, chemicals, oils, coatings, wastewater, food-grade materials, and other process liquids. Air-operated diaphragm pumps are especially useful when the material is abrasive, corrosive, viscous, solids-laden, or difficult to pump.

What does AODD stand for?

AODD stands for air-operated double diaphragm. An AODD pump uses compressed air to move two diaphragms back and forth, creating suction and discharge flow through the pump.

Is a diaphragm pump a positive displacement pump?

Yes. A diaphragm pump is a positive displacement pump because it moves a defined volume of fluid with each pumping stroke.

Can a diaphragm pump run dry?

An air-operated diaphragm pump can usually tolerate dry running better than many other pump styles because it does not rely on close-fitting rotating parts or a mechanical seal. However, extended dry running may reduce diaphragm life, so it should not be treated as ideal operating practice unless the pump and application are designed for it.

Can diaphragm pumps handle solids?

Yes. Diaphragm pumps can handle many fluids with suspended solids, depending on pump size, valve configuration, solids size, and application conditions. For larger solids-handling requirements, review the application carefully and consider specialized pump options.

Are diaphragm pumps self-priming?

Yes. Air-operated diaphragm pumps are self-priming and can draw fluid into the pump from a lower source, depending on the fluid, suction conditions, and pump model. Learn more at What Is Self-Priming?

Do diaphragm pumps need mechanical seals?

No. Diaphragm pumps do not use mechanical seals. The diaphragm separates the pumped fluid from the drive side of the pump, which helps reduce leak points and maintenance concerns.

What is the difference between a diaphragm pump and a centrifugal pump?

A centrifugal pump uses a rotating impeller and is often used for clean, low-viscosity liquids. A diaphragm pump is a positive displacement pump and is often used for difficult fluids, chemicals, slurries, viscous materials, and applications that require self-priming or portable operation.

How do I choose the right diaphragm pump?

Start with the fluid, flow rate, discharge pressure, suction lift, temperature, viscosity, chemical compatibility, and solids content. Then select the proper pump size, body material, diaphragm material, valve material, and air supply requirements. Yamada can help review your application and recommend the right configuration.

Talk to a Pump Expert

Not sure which diaphragm pump is right for your application? Yamada can help you evaluate your fluid, flow rate, pressure, temperature, compatibility requirements, and installation conditions.

Contact Yamada today to speak with a pump expert.

The Proof’s in the Pump