Also available: Electric Diaphragm Pumps
What is an Air Operated Diaphragm Pump
A diaphragm pump is a positive displacement pump which operates with a flexible diaphragm, and integrated check valves. The diaphragm is moved inward & outward toward the pump body which works in conjunction with the check valves and draws in and expels the fluid out the pump casing.
The most common diaphragm pump is an Air Operated Double Diaphragm (AODD) pump.
The AODD is a form of positive displacement pump in which has two pump chambers, a “left” & a “right”. The left and right chambers each have their own diaphragm which interconnect with a shaft so when the one moves, the other one moves proportionality at the same time.
Applications for Air Operated Diaphragm Pumps
Diaphragm Pumps have a wide variety of applications and uses in many industries including food, dairy, pharmaceutical and cosmetic industries, where Stainless Steel pumps are used for these hygienic requirements.
Air pumps are very commonly used in the food sector as the transfer of the fluid does not disrupt the chemical properties and consistency of products such as milk, buttermilk, yogurt, cream, mustard, mayonnaise, ketchup and similar products.
Other uses of AODD pumps include transfer of petroleum products, oil and sludge removal operation, transfer of many types of chemicals, including adhesives, solvents, solvent and water based glues and adhesives, paints and inks. The diaphragm pump is the preferred option for these and other types of chemicals and are widely used as they have the ability to operate safely in a flammable environment.
Types of Diaphragm Pump Air Operated
Positive Displacement Pump
The positive displacement pump provides an approximate constant flow at fixed speed, despite changes in the counter pressure.
Positive displacement pumps all pulsate, meaning that their volume flow within a cycle is not constant. The variation in flow and speed leads to pressure fluctuations due to resistance in the pipe system and in valves.
RAN Aluminium Series Diaphragm Pump
The RAN A series of diaphragm pump is an Air Operated Double Diaphragm (AODD) pump manufactured from high-quality Aluminium.
RAN Atex Certified Diaphragm Pump
The RAN ATEX Certified series diaphragm pumps are an Air Operated Double Diaphragm (AODD) that is designed for use in an environment with an explosive atmosphere.
RAN Cast Iron Series Diaphragm Pump
The RAN C series of diaphragm pump is an Air Operated Double Diaphragm (AODD) pump manufactured from high-quality Cast Iron.
RAN Cast Stainless Steel Diaphragm Pump
The RAN SC series of diaphragm pump is an Air Operated Double Diaphragm (AODD) pump manufactured from high-quality Cast Stainless Steel. They suitable for a variety of applications in many industries such as water transfer, chemicals, paper/pulp, paints, waste water, ceramics, construction, mining, shipping etc.
RAN High Pressure Diaphragm Pump
RAN High pressure pneumatic pumps offer uniquely efficient operations and are suitable for a variety of uses. The self priming high pressure unit is operated with a single diaphragm pump and has ball & seat check valves.
RAN Polypropylene Series Diaphragm Pump
The RAN P series pneumatic diaphragm pump is a Polypropylene Air Operated Double Diaphragm (AODD) pump designed to handle a wide range of substances.
RAN PVDF Series Diaphragm Pump
The RAN PV series of diaphragm pump is an Air Operated Double Diaphragm (AODD) pump manufactured from PVDF material. They can be used to pump hazardous materials, chemicals, slurries and even solids.
RAN Stainless Steel Food Grade Diaphragm Pump
The RAN S series of diaphragm pumps is an Air Operated Double Diaphragm (AODD) pump manufactured from high-quality Food Grade Stainless Steel. They are FDA approved.
Pumping High Viscosity Fluids with RAN Diaphragm Pumps
RAN diaphragm pumps are engineered to handle a wide range of fluid viscosities with reliability and efficiency. However, as with all positive displacement pumps, the viscosity of the fluid has a direct impact on pump performance and capacity.
As viscosity increases, the flow capacity of the pump decreases. This is especially important when dealing with thicker, more resistant fluids. Referencing industry-standard data, RAN diaphragm pumps should not exceed:
- 22,000 centipoise or 100,000 Saybolt seconds universal (SSU) on 3/8″ to 3″ pumps.
- 4,000 centipoise or 18,000 SSU on 1/4″ models.
The graph below illustrates this performance trend, showing a significant decline in pump capacity as viscosity increases. For example, fluids at 10,000 centipoise may reduce pump capacity to nearly 50% of the maximum flow rate achievable with low-viscosity fluids.
Best Practices for Pumping High-Viscosity Fluids
To ensure optimal performance and extend the life of your RAN diaphragm pump, follow these key recommendations:
- Install pumps below or near the fluid level to assist with suction.
- Increase suction line diameter—up to three times the pump’s inlet size—to reduce flow resistance.
- Use dual manifolds where applicable for smoother flow.
- Ramp up air supply gradually using a control valve to avoid pressure surges.
- Note that increasing air pressure beyond a certain point will not increase flow rate—maximum performance is pressure-limited with high-viscosity fluids.
- Consider upsizing the pump if greater capacity is needed for thicker products.
Whether you’re moving adhesives, oils, syrups, or other viscous materials, RAN diaphragm pumps are built to perform. Understanding how viscosity impacts flow and following these operational guidelines will help ensure smooth, efficient transfer of even the most challenging fluids.