A petrochemical facility in Rio de Janeiro, Brazil, selected vinyl ester FRP centrifugal fans for sulfuric acid exhaust duty, the order confirmed in October 2025.
Sulfuric acid mist and vapour attack most metals rapidly, so the exhaust fan handling such an airstream must resist corrosion at the molecular level, and a fibreglass-reinforced plastic laminate with vinyl ester resin is the standard answer because its backbone resists acid penetration better than general-purpose polyester, protecting the structural glass from the chemical front that would otherwise soften the housing. In petrochemical plants the fan sits at the end of a corrosive process, so its material choice decides whether the whole extraction train keeps running, and specifying FRP only for its weight advantage, in a non-corrosive duty, would be the wrong reason and could invite temperature problems the material is not suited to.
Why FRP for Acid Exhaust
Sulfuric acid mist and vapour attack most metals rapidly, so the exhaust fan handling such airstreams must resist corrosion at the molecular level. Fibreglass-reinforced plastic with a vinyl ester resin laminate is the standard answer: the vinyl ester backbone resists acid penetration better than general-purpose polyester, protecting the structural glass from the chemical front that would otherwise soften and weaken the housing.
The application is typical of scrubber outlets and tank-farm ventilation in petrochemical plants, where even short metal exposure leads to thinning housings and eventual failure. Because the fan sits at the end of a corrosive process, its reliability decides whether the whole extraction train stays running, so material choice is a safety and uptime issue, not a line item.
FRP also brings a weight advantage that eases support design, but that benefit is secondary to chemical resistance; specifying FRP only for weight, in a non-corrosive duty, would be the wrong reason and could invite temperature problems the material is not suited to.
Material and Duty Selected
The fans were specified on both chemistry and performance, as shown below.
| Parameter | Selection | Reason |
|---|---|---|
| Resin | Vinyl ester | Sulfuric acid resistance |
| Type | Centrifugal | Pressure for scrubber |
| Airflow | Up to 30,000 m³/h | Process exhaust |
| Pressure | Up to 2,000 Pa | Duct and scrubber loss |
Temperature must also be checked: FRP has a working ceiling well below steel, so the peak exhaust temperature must stay within the laminate's rated range, with margin for upset conditions such as a process excursion that briefly raises the airstream heat.
The centrifugal form was chosen because scrubber duty needs static pressure to push through the scrubber media and the associated ductwork, and a centrifugal's pressure capability suits that better than an axial fan in this resistance range.
Checklist for Corrosive Exhaust Fans
Specifiers should run through this list before releasing an order for acid-duty fans:
- Name the chemical: Match resin to the exact effluent, including trace acids that may be more aggressive than the bulk stream.
- Confirm temperature: Keep peak heat under the FRP limit with margin, and ask about upset scenarios explicitly.
- Size on duty: Select at required pressure and flow, not catalogue max, so the unit runs in its efficient zone.
- Isolate the motor: Keep the drive out of the corrosive stream where possible to extend life and simplify service.
- Plan inspection: Corrosive duty needs periodic wall-thickness checks, because laminate loss is gradual and silent.
- Document the spec: Record resin, temperature, and chemical basis so replacements match the original intent exactly.
Significance for the Plant
Keruite manufactures FRP centrifugal fans, including the expanded range up to size No. 20, at its 80,000 m² Dezhou facility, and the Brazil order shows the product serving a demanding export market. With 30+ years of fan manufacturing and ISO 9001:2015 certification, the company supports corrosive-duty projects where material choice decides service life.
For plant engineers, the lesson is to specify resin by chemistry, not by a generic "FRP" label, and to verify temperature limits as carefully as corrosion resistance. the company backs the selection with in-house performance testing so the quoted duty is measured against the actual curve.
For plant engineers, the discipline is to specify resin by chemistry rather than a generic 'FRP' label, naming the exact effluent including trace acids that may be more aggressive than the bulk stream, and to confirm the peak exhaust temperature stays within the laminate's rated ceiling with margin for upset conditions such as a brief process excursion. The centrifugal form suits scrubber duty because it delivers the static pressure to push through the media and ductwork, and the motor should be isolated from the corrosive stream where possible. With 30+ years of fan manufacturing and ISO 9001:2015 certification at the 80,000 m² Dezhou facility, including the FRP range extended to size No. 20, the company supports corrosive-duty projects where material choice decides service life.
Engineers in Dezhou respond to selection enquiries within 24 hours, and the factory ships most standard fans from its 80,000 m² site within agreed lead times.