The AODD pump is one of the most versatile chemical transfer pumps available — but versatility does not mean it is indifferent to what you put through it. The fluid being pumped determines almost every configuration decision: the body material, the diaphragm, the ball material, the operating conditions, and in some cases whether an AODD pump is the right choice at all.
Here is how the six main fluid types affect your pump selection and what to watch out for in each case.
Corrosive Fluids
Corrosive chemicals attack pump materials from the inside. Sulphuric acid, nitric acid, hydrochloric acid, sodium hydroxide, and similar chemicals will rapidly degrade any wetted component made from an incompatible material — sometimes within days.
The key is matching body and diaphragm material to the specific chemical and its concentration. Polypropylene handles mild acids and alkalis well, but fails quickly with concentrated acids like sulphuric 98% or nitric 68%. PVDF is the correct choice for these aggressive chemicals — it offers significantly wider chemical resistance and better temperature tolerance than polypropylene. PTFE is the diaphragm material of choice for the most aggressive chemicals, as it is chemically inert across almost the entire pH range.
A common mistake is selecting material based on the chemical name alone without accounting for concentration. A pump body that is compatible with dilute sulphuric acid may not survive contact with the 98% concentrated version. Always check compatibility against both chemical and concentration before specifying.
Abrasive Fluids
Abrasive fluids contain solid particles — ceramic slurries, paints, certain inks, coagulants — that grind against internal pump surfaces with every stroke cycle. The damage is gradual but cumulative, and the severity depends on particle size, hardness, and concentration.
For abrasive service, body material selection shifts toward wear resistance rather than chemical resistance alone. Stainless steel 316 handles abrasion better than plastic bodies in most cases. For the diaphragm, elastomers like Santoprene absorb abrasive impact better than PTFE, which — being rigid — is more susceptible to surface erosion from hard particles. If the fluid is both abrasive and chemically aggressive, you are managing a tradeoff and may need to compromise on one axis to protect the other.
Stroke rate matters significantly in abrasive applications. Running the pump faster than necessary increases the number of abrasive impact cycles per hour and accelerates wear. Use the minimum air pressure and stroke rate that achieves your required flow.
Toxic Fluids
Highly toxic fluids — mercury compounds, certain pesticide concentrates, lead-based solutions — require maximum containment. A single leak point is unacceptable.
This is one of the strongest arguments for the AODD pump in toxic fluid applications. The seal-less design eliminates the mechanical seal, which is the most common leak point in conventional centrifugal and gear pumps. There are no rotating shaft penetrations in contact with the fluid.
For critical containment applications, some manufacturers offer twin-diaphragm configurations with leak detection between the diaphragm layers. If the inner diaphragm fails, the outer diaphragm contains the fluid and a sensor triggers an alarm before any release occurs. This adds meaningful protection in applications where any escape of fluid carries serious consequences.
Flammable Fluids
Acetone, benzene, petroleum products, and other flammable liquids introduce a specific risk: static charge buildup. As fluid moves through the pump and piping, static electricity can accumulate — and in a flammable atmosphere, a spark is a serious hazard.
AODD pumps are inherently well-suited for flammable fluid applications because they run on compressed air, not electricity. There are no motors, no electrical connections at the pump itself, and no ignition sources from the pump body.
However, the static risk still needs to be managed. Grounding the pump and piping system is essential. For applications in classified hazardous areas — zones where explosive atmospheres may be present — an ATEX-certified pump is mandatory. The standard pump body in conductive material (conductive PP or conductive PVDF) provides the groundability path; standard plastic bodies do not. Do not assume that an air-powered pump is automatically safe in an explosive atmosphere without verifying the ATEX certification and grounding requirements.
Shear-Sensitive Fluids
Some fluids change their properties when subjected to mechanical shear — the tearing and turbulence that high-speed impellers create. Polymer solutions used in water treatment are the most common industrial example: high shear degrades the polymer chain, reducing its effectiveness as a flocculant. Emulsions, food products, and certain biological additives behave similarly.
The AODD pump is one of the best options for shear-sensitive fluids precisely because of its low-shear operating principle. The diaphragm displaces fluid gently rather than accelerating it through a high-speed impeller. Running the pump at a reduced stroke rate further minimises shear.
The practical limit is flow rate. AODD pumps handle shear-sensitive fluids well at modest flow rates, but as you scale up, the stroke volume per cycle and the velocity through the check valves both increase. For very high flow rates in shear-sensitive applications, the pump selection needs to balance the shear advantage against the flow requirements carefully.
High Vapour Pressure Fluids
Hydrocarbons and certain fuels have relatively high vapour pressures — they vaporise readily when local pressure drops below the vapour pressure of the fluid. In a pump, this happens most easily at the suction inlet, where pressure is lowest. The result is vapour lock: the pump is drawing vapour instead of liquid, loses prime, and delivers erratic or zero flow.
For these fluids, suction conditions are critical. Minimise suction lift wherever possible — ideally, install the pump with flooded suction so the fluid arrives at the inlet under positive pressure. Keep suction lines short and direct to minimise friction losses that further reduce inlet pressure. Run the pump at a lower stroke rate to give the fluid more time to fill the chamber between strokes.
If vapour lock persists despite good suction design, consider whether a different pump type is more appropriate for the application. AODD pumps handle most hydrocarbon applications well, but extreme cases — very high vapour pressure fluids at elevated temperatures — may be better served by a pump with a flooded inlet and lower suction requirements.
The Core Principle
Every fluid property — chemical aggressiveness, abrasive content, toxicity, flammability, shear sensitivity, vapour pressure — has a direct consequence for how an AODD pump is specified, installed, and operated. Getting one wrong does not just reduce pump life. It can create a safety risk, contaminate a process, or cause repeated unexplained failures that no amount of pump quality can prevent.
Start with the fluid. Everything else follows from there.
Autoflo Technology is the official distributor of the Fluimac Phoenix AODD Pump in Malaysia. If you need help specifying the right configuration for your fluid, contact us at info@autoflotechnology.com.