[labnetwork] Galvanized steel for air-return surfaces

[Nicholas Menounos]

Hi Joe,

I have never seen powder coated Al duct in large sizes, but my intuition is that it would rival installed cost of SS.

Galvanized is the most common return air material in industry (nano returns are G-90 = extra thick coat), but we only have ducted returns in the ISO7 spaces (main cleanroom is open plenum).

For areas with significant corrosive chemical quantities and high likelihood of spills (e.g. wet etching bays), I would consider 316SS upgrade (esp if the duct is buried) to future proof. Potential for zinc salts/corrosion particles that reduce HEPA life is low, but we often lack funding and detection methods post occupancy...Limiting the upgrade to wet bays, significantly reduces scope.

Best,
Nick Menounos, PE
MIT.nano - Associate Director of Infrastructure
Cell: (508) 932-0938<tel:+15089320938>

From: labnetwork <labnetwork-bounces at mtl.mit.edu> On Behalf Of Joseph Losby
Sent: Monday, May 4, 2026 12:50 PM
To: Lab Network (labnetwork at mtl.mit.edu) <labnetwork at mtl.mit.edu>
Subject: [labnetwork] Galvanized steel for air-return surfaces

Hello Labnetwork,

We are designing an ISO 5 facility using a bay-and-chase layout.  Do you recommend the use of galvanized steel for recirculating air-return surfaces (only), specifically regarding long term risks of zinc oxide shedding or oxidation? All air return is refiltered before entering the cleanroom.

Would powder-coated aluminum be a better option?  Although stainless steel would be used for the ducting between the AHUs and cleanroom HEPA filters (as well as all exhausts), the use of galvanized upstream is mainly a value engineering consideration.

Cheers,
Joe


Joseph Losby, PhD

Manager, qLab Operations

Quantum City, Office of the VPR

joseph.losby at ucalgary.ca<mailto:joseph.losby at ucalgary.ca>
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