Get Your All-Flo Pumps and Parts Now With FREE SHIPPING - Ends 2/28. SHOP NOW >
AODD vs Centrifugal Pumps: Why “Either Works” May Be Wrong
Air-operated double diaphragm (AODD) and centrifugal pumps can both move fluid, but they fail and recover in fundamentally different ways. When engineers say, “either one works,” they are usually overlooking suction stability, air ingestion, pressure variability and maintenance realities, where the wrong pump choice can lead to chronic failures.
Contributors
This blog was developed using expert insights from PSG® subject matter experts who support pump selection, troubleshooting and system design across oil and gas, chemical processing, wastewater and industrial applications.
When a pump discussion ends with “either one works,” it usually means the system has not been fully defined. While both AODD and centrifugal pumps may deliver the same nominal flow rate on paper, they can behave very differently under real operating conditions.
In stable, clean systems with constant suction and discharge conditions, multiple pump technologies may function acceptably. In real industrial environments, suction fluctuates, air enters systems, fluids change and operators interact with equipment in unpredictable ways.
Under these conditions, the differences between AODD and centrifugal pumps become decisive.
The goal of pump selection is not to identify a pump that works occasionally, but one that can continue working when conditions degrade.
How Centrifugal Pumps Behave
Centrifugal pumps impart velocity to fluid and convert that velocity into pressure. This operating principle makes them efficient and cost-effective when conditions remain within a relatively narrow operating window.
However, centrifugal pumps are highly sensitive to system changes. Flow rate is directly tied to discharge pressure, so as system resistance increases, flow decreases.
When suction conditions deteriorate or vapor forms at the inlet, performance can collapse rapidly.
Centrifugal pumps also rely on continuous liquid flow for cooling and lubricating mechanical seals. Even a brief loss of prime can overheat seals and accelerate failure.
In market applications such as produced water handling, chemical flushing or utility services where suction is stable and air ingestion is minimal, centrifugal pumps, including designs from manufacturers such as Griswold®, can perform very well.
When those assumptions no longer hold, reliability declines quickly.
How AODD Pumps Respond to the Same Conditions
Air-operated double diaphragm (AODD) pumps move fluid by alternately pressurizing diaphragms with compressed air. This decouples liquid movement from suction stability and discharge pressure in a way that fundamentally changes failure behavior.
When air enters the suction, an AODD pump continues to stroke. When discharge is blocked, the pump stalls safely instead of over-pressurizing the system. When suction conditions recover, the pump resumes normal operation without external priming or intervention.
These characteristics make AODD pumps tolerant of air ingestion, intermittent operation and variable system conditions. Products from manufacturers such as Wilden® and All-Flo™ are commonly selected for these environments because wear is confined to serviceable components such as diaphragms and valve assemblies. The tradeoff is pulsating flow and lower efficiency compared to centrifugal pumps operating under ideal conditions.
Suction Conditions: The Real Divider Between Success and Failure
Suction stability is often the single most important factor separating successful centrifugal pump applications from chronic failures.
If suction pressure and liquid level remain consistent, centrifugal pumps deliver smooth, continuous flow. If suction fluctuates due to tank level changes, long suction lines or entrained air, centrifugal pumps lose prime and struggle to recover without intervention.
AODD pumps are far less sensitive to suction instability. They tolerate poor suction and continue operating under conditions that would stop a centrifugal pump entirely. When designers assume suction will be stable, but field conditions prove otherwise, the pump's choice itself becomes the failure mechanism.
Air ingestion, pressure swings and intermittent operation accelerate wear on seals, diaphragms and internal components across pump types. Replacing worn parts with genuine components helps restore original performance, maintain proper sealing and prevent recurring reliability issues in both AODD and centrifugal pump systems.
Pressure Variability and Deadhead Scenarios
Centrifugal pumps respond to discharge pressure changes by moving along their performance curve. Increasing pressure reduces flow but does not stop the pump.
AODD pumps behave differently. When discharge pressure exceeds available air pressure, the pump simply stops moving fluid. This stall-on-deadhead behavior protects piping and downstream equipment from overpressure without additional control hardware.
In systems where discharge valves may be closed, hoses may kink or operators may intervene manually, this behavior can prevent catastrophic failures.
In tightly controlled systems with constant discharge conditions, centrifugal pumps may be perfectly appropriate and simpler to operate.
Maintenance Reality and Wear Behavior
Centrifugal pumps concentrate wear in seals and bearings. Seal failures are inevitable over time and require disciplined maintenance planning, particularly in abrasive or chemically aggressive service.
AODD pumps concentrate wear in diaphragms, valve balls and seats. These components are consumable by design and can often be replaced without removing the pump from service. Maintenance teams frequently prefer AODD pumps in harsh or unpredictable environments because failures are predictable and contained.
Positive displacement rotary pumps, including sliding vane designs from Blackmer®, sit between these extremes. They provide consistent flow and self-priming capability but require stable suction conditions and appropriate relief strategies to prevent damage.
Where Each Pump Type Fits Best
Centrifugal pumps are best suited for high-flow, clean or lightly contaminated fluids with stable suction and discharge conditions. Common examples include utility water, flushing systems and certain produced water services with controlled solids.
AODD pumps excel in applications involving air ingestion, intermittent operation, variable viscosity, chemical exposure or uncertain suction. Typical examples include chemical unloading, sumps, drainage, bilge pumping and temporary bypass service.
Problems arise when centrifugal pumps are installed in AODD-type applications or when AODD pumps are forced into roles where smooth, continuous flow is critical without mitigation.
Designing Systems Instead of Debating Pumps
Debates between AODD and centrifugal pumps often miss the point. The pump is a response to system behavior, not the starting point.
Effective selection begins by defining suction conditions, pressure variability, air ingestion risk and maintenance capability. Once those factors are understood, the appropriate pump technology usually becomes clear.
When those factors are unknown or assumed away, “either one works” becomes an expensive assumption.
For early-stage narrowing of pump options based on system behavior, the pump finder can help align applications with appropriate technologies. Additional background on diaphragm operation is available in resources covering AODD technology.
If a system experiences repeated pump failures or inconsistent performance, the issue is rarely the pump alone. Suction layout, operating discipline and system assumptions must be evaluated together.
Application specialists routinely determine whether a centrifugal or AODD pump is appropriate by examining failure patterns, operating history and system geometry. Engaging support early reduces misapplication risk and shortens resolution time. Technical assistance is available through the contact us page.
For additional information, please review our returns policy, shipping policy and terms and conditions, including our terms of use.
Contributors
Steve Cox
Steve Cox has decades of experience across diaphragm, vane and centrifugal pump technologies supporting industrial, chemical and energy markets. His background includes field troubleshooting, application guidance and system-level reliability improvement.
Nick Watt
Nick Watt supports pump selection and application engineering for hydrocarbon, chemical and industrial systems. His experience includes evaluating positive displacement and centrifugal technologies under real-world operating conditions and competitive applications.
Find Your Pump
Just answer a few questions, and our Pump
Finder will guide you to the right solution!
PUMP FINDER
© 2026 PSG Dover All Rights Reserved