Most buyers treat a wet scrubber like a catalog item. Pick the right flow rate, confirm the corrosion resistance, and move on. That works until it doesn't—and when it doesn't, you're retrofitting options that should have been designed in from the start, or running a system that's costing more to maintain than it should.
The scrubber is one part of a larger air pollution control system. What you specify upfront—packing depth, automation level, secondary containment, and the ductwork material connecting it all—determines how well the system performs, how long it runs, and what it actually costs across its service life.
Here's what to think through before anything gets fabricated.
Every design conversation starts in the same place: your process data. Without it, nothing else is reliable.
Required process inputs before design begins:
These inputs are crucial because they not only guide the design process but fundamentally dictate which customization options can even be considered. A semiconductor acid scrubber handling hydrofluoric exhaust has completely different requirements than an ammonia scrubber at a municipal wastewater plant. Get the process data locked down first.
Then the customization conversation has somewhere to go.
We'll be direct about this: options added after fabrication begins cost more and sometimes can't be accommodated. Ensure you work through the list below before the purchase order is finalized, rather than waiting until after the scrubber has shipped.
Standard packing depth in a packed bed wet scrubber is 60 inches. Upgrading to 72 inches improves removal efficiency for demanding applications, such as acid scrubbers handling high contaminant concentrations. The tradeoff is increased static pressure drop, which affects fan selection. Worth the discussion if you're working with tight compliance margins.
A few that consistently justify themselves:
Secondary containment is the one option most buyers underestimate until a regulator raises the question. If your scrubber handles concentrated acids or hazardous chemicals, partial or full containment built into the original design costs a fraction of retrofitting it later.
This is where the widest range of options lives — and where buyers most often over- or under-specify.
A basic industrial wet scrubber can run with manual gauges and analog controls. That's adequate for smaller, lower-stakes applications. A fully automated system adds a PLC, HMI operator interface, pH controller, level transmitters, and VFDs on pump motors. For semiconductor fabs and chemical facilities running 24/7 processes, that automation earns back quickly in reduced operator time and earlier problem detection. For a smaller batch operation with weekly manual checks, it may be overhead you don't need.
The controls decision also drives your enclosure spec. Outdoor installations require NEMA 4X corrosion-resistant enclosures. For locations experiencing significant temperature variations, installing heaters within all enclosures is essential to protect the electronics from moisture damage.
The scrubber body is typically FRP. The ductwork connecting your exhaust sources to the scrubber inlet is where the material decision gets more consequential, and where a lot of projects default to price rather than performance.
Two materials dominate corrosive air duct applications: fiberglass reinforced plastic duct systems and SSTeelcoat coated stainless steel ductwork. Both handle corrosive exhaust. On nearly every performance dimension, though, they are not equal.
SSTeelcoat is 304 or 316 stainless steel internally coated with Halar® (ECTFE) via electrostatic powder coating. Across six categories—service life, ease of installation, maintenance, impact and durability, fire behavior, and code approval path—SSTeelcoat outperforms FRP. That's not positioning language. It's the comparison data.
Service life runs 30+ years, typically. FRP runs 20+ years, with degradation rates dependent on resin formulation and chemical exposure. That decade of additional service life compounds: one fewer replacement cycle over a facility's life, avoided downtime, and avoided contractor costs.
Installation is faster. The bolt-together Van Stone flange system requires no welding and no resins in the field. A crew that's never touched an FRP lamination job can install SSTeelcoat correctly. That matters when schedules are tight and field labor is expensive.
The fire rating credential is often the deciding factor before anything else. SSTeelcoat carries a Class 1 fire rating per ASTM E-84, complies with NFPA 820 and FM 4922, and handles continuous temperatures up to 300°F. In occupied facilities or code-sensitive environments, that rating can eliminate the requirement for internal sprinklers, and may reduce insurance costs. FRP is a combustible composite. Its code and approval path are conditional, not broad.
The honest tradeoff: SSTeelcoat carries a higher upfront material cost than FRP. On large-diameter or long runs, that difference is real. But when you run the lifecycle math—30+ years versus 20+, excellent maintenance versus fair, bolt-together install versus field lamination—SSTeelcoat consistently delivers lower total cost of ownership. The upfront premium pays for itself. In semiconductor, pharmaceutical, and aerospace facilities where a duct replacement means process downtime, it pays back faster.
SSTeelcoat is the right choice for: most industrial corrosive air applications, particularly indoor installations, code-sensitive facilities, high-uptime environments, and any project where you're making a long-term investment rather than minimizing the line item.
FRP (Fiberglass Reinforced Plastic) ductwork is a highly effective choice for industrial air pollution control systems. Its ability to manage a diverse array of acids, alkalis, and solvents makes it versatile, with the specific chemical resistance determined by the selection of the resin. It's lighter than steel, which matters when structural load calculations are tight. And for outdoor runs, large-diameter duct, or systems where matching an FRP scrubber body simplifies thermal expansion management at connection points, it's a functional choice.
We'll be direct about where FRP falls short. Installation rates are poor on the comparison scale—field lamination requires trained crews, cure time, and controlled conditions. Get it wrong and you have leak points. Maintenance rates are fair versus excellent for SSTeelcoat, meaning more frequent inspection and more opportunity for degradation to go unnoticed. And the combustible composite classification creates a harder path through fire code review in occupied or code-governed spaces.
FRP air duct makes sense when:
For everything else, the lifecycle math favors SSTeelcoat.
Buy your FRP air duct from one vendor, your industrial wet scrubber from another, and your fan from a third. On paper, everything looks coordinated. In the field, airflow doesn't match the design. Pressure drops exceed predictions. Flanges don't align.
That's not a hypothetical, but a pattern.
A single-source manufacturer designs the fan curve against actual system resistance — every fitting, the real scrubber pressure drop, stack effect included. The ductwork gets fabricated to match the scrubber inlet exactly. Controls are specified to match the system's operating logic. When something needs attention, one engineering team owns the answer. One call. One set of documentation. One source for replacement parts.
Viron is the only manufacturer in the United States that builds complete corrosive air systems in-house—hoods, ductwork, scrubbers, fans, dampers, and stacks—all available in SSTeelcoat, FRP, or PVC. That's the reason systems go in on schedule and run without surprises.
If you're specifying a wet scrubber system and want to talk through your process data and options, contact Viron today. We'll give you a straight answer on what makes sense for your application.