Resin systems often involve high viscosity, solvent content, shear sensitivity, and potential curing risks. Improper pump selection can result in leakage, excessive wear, product degradation, or safety concerns in hazardous environments.
This FAQ provides technical guidance for engineers evaluating resin transfer pumps, particularly air operated diaphragm (AODD) pumps, in industrial applications.
Table of Contents
What is the most suitable pump type for high-viscosity resin?
For high-viscosity resin, a positive displacement pump is generally preferred over centrifugal designs.
Centrifugal pumps rely on rotational velocity and are highly sensitive to viscosity changes. As viscosity increases, efficiency drops significantly and flow becomes unstable.
Air operated diaphragm (AODD) pumps are often selected because:
- Flow rate is less affected by viscosity
- They can handle thick, non-Newtonian fluids
- They do not rely on high rotational speed
For medium to high viscosity epoxy or polyester systems, AODD pumps provide stable and predictable transfer performance.
Are AODD pumps suitable for solvent-based or flammable resins?
Yes, provided that appropriate safety measures are implemented.
Solvent-based polyester and coating resins may generate flammable vapours. In such environments, ignition risk must be minimised.
AODD pumps offer advantages because:
- They are pneumatically driven
- There is no electric motor at the pump head
- They operate without mechanical shaft seals
With proper grounding and, where required, ATEX-compliant configuration, diaphragm pumps are commonly used in hazardous resin processing areas.
Can diaphragm pumps handle epoxy resin safely?
Yes. Epoxy resin transfer is one of the most common applications for diaphragm pumps.
When selecting a pump for epoxy systems, attention should be given to:
- Diaphragm material (typically PTFE)
- Chemical compatibility of the pump body
- Operating temperature
Aluminium and stainless steel pump bodies are frequently used. The seal-less design reduces the risk of leakage compared to mechanical seal pumps, particularly in systems where maintenance intervals may be extended.
Do diaphragm pumps create shear that may damage resin formulations?
Compared to high-speed centrifugal or gear pumps, diaphragm pumps generate relatively low shear.
This is relevant for:
- Shear-sensitive epoxy systems
- Specialty coating resins
- Adhesive formulations
Because AODD pumps operate through reciprocating displacement rather than continuous high-speed rotation, they are often selected where product integrity must be preserved.
However, system design (air pressure, stroke frequency) should still be optimised to avoid unnecessary stress on sensitive materials.
How can resin curing inside the pump be prevented?
Resin curing inside the pump is a known operational risk, particularly with reactive systems.
Preventive measures include:
- Flushing the pump after extended downtime
- Avoiding long idle periods with resin inside the chamber
- Maintaining controlled ambient temperature
- Selecting diaphragm materials resistant to chemical attack
One practical advantage of diaphragm pumps is their relatively simple internal design, which allows easier inspection and cleaning compared to shaft-driven alternatives.
What materials are recommended for resin transfer pumps?
Material selection must consider chemical resistance, temperature, and solvent content.
Common Pump Body Materials:
- Stainless Steel (AISI 316) – suitable for aggressive or elevated temperature systems
- Aluminium – widely used for solvent-based resins
- Polypropylene (PP) – appropriate for water-based or less aggressive formulations
- PVDF – for enhanced chemical resistance
Common Diaphragm Materials:
- PTFE (Teflon) – high chemical resistance, suitable for most epoxy and polyester resins
- Elastomer-backed PTFE – improved flexibility with chemical protection
Compatibility testing is recommended when dealing with specialised or modified resin systems.
How does an AODD pump compare to a gear pump in resin applications?
Both pump types are used in resin systems, but their operational characteristics differ.
| Parameter | AODD Pump | Gear Pump |
|---|---|---|
| High Viscosity Handling | Very good | Excellent |
| Dry Run Capability | Yes | No |
| Mechanical Seals | No | Yes |
| Shear Level | Low to moderate | Moderate |
| Maintenance Sensitivity | Low | Moderate |
Gear pumps may offer precise flow control in certain dosing applications. However, AODD pumps are often preferred where:
- Dry run conditions may occur
- Seal leakage must be avoided
- Hazardous environments are involved
The final selection should be based on process requirements rather than pump type alone.
Can diaphragm pumps operate dry during resin transfer?
Yes. One operational advantage of AODD pumps is their ability to run dry without immediate damage.
This is particularly useful for:
- Drum emptying operations
- Batch transfer systems
- Intermittent feed processes
Dry-running capability reduces the risk of failure during short-term supply interruptions. Nevertheless, continuous dry operation should be avoided where possible to reduce wear.
Conclusion
Resin transfer requires careful consideration of viscosity, chemical compatibility, safety classification, and process stability.
Air operated diaphragm pumps are widely used in epoxy, polyester and industrial resin systems due to:
- Positive displacement performance
- Seal-less construction
- Suitability for hazardous environments
- Relative ease of maintenance
Proper selection should always consider:
- Resin formulation
- Operating temperature
- Hazard classification
- Required flow rate and pressure
- Cleaning and maintenance strategy
To learn more about the detailed application cases, you can refer to this article: [AODD Pumps for Handling High-Viscosity & Flammable Resins ]
