Indoor Pool Chloramine Corrosion
What happens in the pool hall
Chloramines form in pool water when chlorine reacts with nitrogen compounds from bathers. The volatile ones escape into the air, which is already warm and very humid. On a cooling or dehumidifying coil they dissolve into the condensate film, forming an acidic, chloride-rich solution.
What corrodes
Aluminium fins pit, copper tubes corrode, and even stainless steel fixings can crack in pool air. Heat-recovery coils in the exhaust air stream see the highest loads.
Protection
Coat every coil that sees pool-hall or exhaust air with a chemical-resistant system, keep ventilation working, and inspect coils more often than in ordinary buildings.
ISO 9223 corrosivity category
Typical category for this environment: C4–C5.
- C1Very low
- C2Low
- C3Medium
- C4High
- C5Very high
- CXExtreme
Recommended protection by location
| Condition | ISO 9223 | Recommended system | Note |
|---|---|---|---|
| Dehumidifier and AHU coils in pool-hall air | C5 | PG-C Air-dry 2K | Chemical-resistant film; confirm fin spacing allows the film build. |
| Heat-recovery coils in exhaust air | C5 | PG-C Air-dry 2K | Exhaust carries the highest chloramine load. |
| Outdoor condensers serving the pool plant | C4 | PG-S1 Polysiloxane sol-gel | Outside the pool hall; coat for the outdoor site category. |
Not sure which category your site falls into?
Enter distance from the sea, humidity and nearby industry to get an estimated ISO 9223 category.
Related
- CoatingsAir-Dry Two-Component Chemical-Resistant Coating
- EquipmentAHU Coil Coating
- EnvironmentsIndustrial Atmospheres (SO₂, NOx, Chlorides)
- ServiceApplication of Customer-Specified Coatings
- GuidesCan One Coating Handle Salt and Industrial Pollution Together?
- CoatingsWaterborne Polysiloxane (Sol-Gel) Coil Coating
Also see
- EquipmentEvaporator Coil Coating
- GuidesHow to Select a Coil Coating for Your Project
- CoatingsBaked Phenolic Coil Coating
- EquipmentHeat Pump Coil Protection
Are chloramines the same as chlorine?
No. They form when chlorine reacts with nitrogen compounds from bathers. Trichloramine is volatile, gives the typical pool smell, and is the main corrosive agent in pool-hall air.
Does ventilation solve the problem?
Good ventilation lowers chloramine levels but does not remove them. Coils in the pool-hall airstream still need a chemical-resistant coating.
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