How do I select damper blade and frame material for corrosive environments?

For standard commercial HVAC applications, galvanized steel (G90 coating) blades and frames are adequate and cost-effective. For mildly corrosive environments such as parking garage exhaust or pool dehumidification systems, 304 stainless steel construction is recommended to resist chloride corrosion. For laboratory fume hood exhaust, chemical storage areas, or coastal installations with salt spray, 316 stainless steel with Teflon bearings and stainless steel axles/jamb seals is required because the molybdenum content provides superior pitting resistance. For the most aggressive environments (acid exhaust, wastewater treatment), all-plastic dampers with PVC or polypropylene blades, fiberglass-reinforced frames, and Hastelloy or titanium hardware may be necessary — and the actuator must also be protected with NEMA 4X/IP66 enclosures. Always verify material compatibility using the Corrosion Resistance Guide from the damper manufacturer and match the blade material to the duct construction material for galvanic compatibility.