Resin selection determines an FRP fan's chemical resistance; isophthalic suits general duty while vinyl ester resists stronger chemicals.
Why Resin Matters
A fibre-reinforced plastic fan is only as corrosion-resistant as its resin matrix, because the glass fibres are protected by the surrounding polymer; once the resin is attacked, the structure weakens and the impeller can fail without obvious warning.
An FRP fan lives or dies by its resin because the glass fibre is only as protected as the polymer around it; once the resin is attacked the structure weakens from the inside with little warning. The resin choice is therefore a corrosion decision first and a cost decision second.
Isophthalic polyester covers a wide band of mild acids, alkalis, and salts at moderate temperature and is the economic general duty, while vinyl ester resists strong acids, oxidisers, and solvents and tolerates a wider temperature band, at a higher price. Epoxy fills the gaps where high temperature or specific solvents beat polyester chemistry.
The selection is made from a compatibility table listing each chemical at its actual concentration and temperature, because resistance falls as either rises and a pass at low strength can become a fail at full concentration. The peak temperature, not the average, is given weight, since occasional excursions do the damage.
Construction can split the job: a chemical-resistant inner layer over a structural outer layer gives protection where it is needed and strength where the impeller sees centrifugal and thermal stress, without paying for vinyl ester through the whole laminate. The two layers are selected together so neither compromises the other.
The company's 80,000 m² production site builds FRP fans under ISO 9001:2015 with CCC certification, and its engineers respond to selection enquiries within 24 hours to match resin and laminate to the real chemical stream, concentration, and temperature the fan will see in service.
The resin choice is matched by an outer gel coat or UV-stable layer for units exposed to weather, because the polyester or vinyl ester laminate itself ages under sunlight and the surface is protected so the structure underneath stays sound. Where the airstream can carry static charge, a conductive grade is specified so a spark does not ignite the very vapour the corrosion-resistant resin was chosen to survive, and the spark resistance is part of the duty review alongside the chemical table.
Isophthalic polyester resin offers good resistance to a wide range of mild acids, alkalis, and salts at moderate temperature, and is the common economic choice for general corrosive ventilation such as wash-down areas and mild exhaust streams.
Vinyl ester resin has a molecular structure that resists strong acids, oxidisers, and solvents better than isophthalic, making it the selection for aggressive chemical duty despite higher cost, and it also tolerates a wider temperature band in service.
Epoxy-based matrices appear where high temperature or specific solvent resistance is needed, rounding out the choices for unusual process streams and giving the specifier a route when polyester chemistry is inadequate for the duty.
Matching Resin to Duty
The selection starts from a chemical compatibility table listing each stream the fan will see, at its actual concentration and temperature, because resistance falls as either rises and a pass at low concentration can become a fail at full strength.
Temperature is decisive: a resin safe at 40°C may fail at 80°C in the same chemical, so the operating and occasional peak temperatures must both be within the resin's rated range, with the peak given proper weight in the choice.
A blended or dual-layer construction, with a chemical-resistant inner layer over a structural outer layer, gives both protection and mechanical strength without paying for vinyl ester throughout, which is often the most economical sound design.
Mechanical load still applies; the resin choice must not compromise the laminate's strength where the impeller sees centrifugal and thermal stress during operation, so the structural layer and the corrosion layer are selected together, not independently.
| Item | Specification | Note |
|---|---|---|
| Isophthalic | general | Mild acid/alkali |
| Vinyl ester | aggressive | Strong acid/solvent |
| Epoxy | high temp | Special streams |
| Temp | rises=worse | Check peak |
| Layup | dual layer | Protect + strength |
| Table | by chemical | Conc. + T |
Selection Checklist
- List every chemical, concentration, and temperature the fan will see.
- Use isophthalic for general mild-corrosion ventilation.
- Specify vinyl ester for strong acids or solvents.
- Confirm the resin rating covers the peak temperature, not just normal.
- Consider a dual-layer laminate for protection and strength.
- Do not let resin choice undermine the mechanical laminate.
About the Manufacturer
Keruite Air Conditioning Group, headquartered in Dezhou, Shandong, has more than 30 years of HVAC manufacturing experience and operates an 80,000 m² production site with its own performance testing laboratory. Products are built under ISO 9001:2015 quality management and carry CCC certification, and are supplied to customers in over 50 countries.
Our engineers respond to selection enquiries within 24 hours and can provide project-specific sizing, performance curves, and documentation to support specification and procurement.