If you’ve ever walked past a warehouse loading dock, stood in a commercial kitchen venting excess steam, or adjusted the climate control in a large office building, you’ve likely felt the quiet, steady push of a backward centrifugal fan at work. As someone who’s spent 12 years supplying these fans to industrial and commercial projects across North America, I’m often asked a deceptively simple question: “What are these fans actually made of?” It’s not just a matter of slapping metal together and calling it done—backward centrifugal fans are engineered to move air efficiently, resist wear, and hold up to years of demanding use, so every material choice has a purpose. Today, I’m breaking down the core materials we rely on (and why we don’t cut corners on any of them) to build fans that our clients trust to perform, even when conditions get tough. Backward Centrifugal Fans
First, let’s start with the heart of the fan: the impeller. This is the curved metal wheel that spins inside the fan housing, drawing air in the center and throwing it outward at high velocity. For backward curved impellers (the key design that makes these fans more energy-efficient than forward-curved alternatives), the blades are mounted at a backward angle, so the shape and material of those blades matter most. For most general commercial applications—think office building ventilation, retail center exhaust, or light manufacturing—we use galvanized steel for impellers. Galvanization means a layer of zinc is bonded to the steel via a hot-dip process, which stops rust from forming, even in humid spaces or areas where the fan might sit idle for long stretches. I remember a client who installed our galvanized impeller fans in a hockey arena’s ice plant in upstate New York; they’d had cheap, uncoated impellers from another supplier rust through in just two years, but our galvanized units are still going strong after seven. That said, galvanized steel isn’t the only option. For applications with mild chemical exposure, like food processing plants handling fruit acids or flour dust, we step up to aluminum alloy impellers. Aluminum is lighter than steel, which cuts down on the motor load and reduces energy use over the fan’s lifespan, plus it’s naturally corrosion-resistant even in slightly acidic or damp environments. I’ve also had clients in agricultural settings (like grain storage facilities) request stainless steel impellers, because grain dust is abrasive and can wear down softer metals. 304 stainless steel is our go-to here—it resists both abrasion and rust, even when fans are dusty or exposed to spilled fertilizer residue.
Moving beyond the impeller, the fan housing (the large, scroll-shaped casing that contains the spinning wheel) is the next critical component. The housing doesn’t just hold everything together—it also shapes the air flow to direct it where it needs to go, so its material has to be rigid and smooth to avoid turbulence and efficiency loss. For standard low- to medium-pressure applications, we stick with the same galvanized steel we use for impellers, usually 16-gauge or 14-gauge depending on the fan size. Thicker gauges for larger fans, because a bigger scroll has to support the impeller’s weight and resist the pressure of moving more air. But for high-pressure applications, like fume extraction from chemical manufacturing or exhaust from industrial ovens, we use heavier-gauge carbon steel instead. Carbon steel is stronger than galvanized steel, so it can handle the higher internal pressures without warping or leaking. We always paint these carbon steel housings with a powder coat finish after fabrication—usually an epoxy-based coating that resists chipping, chemicals, and UV light. That’s a big win for outdoor applications, like rooftop ventilation systems, where sun exposure and temperature swings would make regular paint peel. For food and pharmaceutical facilities, where cleanliness is non-negotiable, we offer stainless steel housings too, usually 304 or 316 grade. 316 stainless is even more corrosion-resistant than 304, with added molybdenum that stands up to harsh cleaning chemicals used in these industries, and it’s easy to wipe down without holding onto bacteria or residue.
Next up: the drive system, which is how we power the impeller. Most backward centrifugal fans use either direct drive or belt drive systems, and the materials here are designed to reduce friction, extend motor life, and handle consistent use. For direct drive fans—where the impeller is mounted directly to the motor shaft—we use high-grade electrical steel for the motor core, laminated to reduce energy loss from magnetic interference. The motor housing itself is made of cast aluminum, because it’s lightweight and dissipates heat well, which keeps the motor from overheating during long run times. For belt drive fans, which are preferred for larger sizes or applications that require variable speed adjustment, we use premium V-belts made of neoprene with a polyester tension core. These belts are more durable than rubber-only belts, resistant to stretching, and don’t slip even when the fan is running at high speeds. We also use cast iron for the pulley wheels in belt drive systems, because cast iron holds up to the constant tension and doesn’t wear down as fast as aluminum pulleys over time. I once had a client in a 24/7 packaging plant who switched from our old belt drive setup with aluminum pulleys to our cast iron pulleys—they reported cutting belt replacement time by half, which saved them thousands in downtime over the year.
Then there are the small, often overlooked parts that make the whole system work: the bearings, gaskets, and mounting hardware. These are the components that people rarely notice until they fail, so we never skimp on their materials. For bearings in both direct and belt drive fans, we use sealed ball bearings made of high-carbon chrome steel. Sealed bearings mean no need for regular lubrication, which is perfect for hard-to-reach fans like rooftop units or fans inside ductwork, and chrome steel is harder than standard steel, so it resists wear from the constant spinning of the impeller. For gaskets, which seal gaps between the housing and the access panel or intake/outlet flanges to prevent air leaks, we use closed-cell neoprene foam. It’s flexible, so it compresses to create a tight seal, and it resists temperature changes and mild oils, so it doesn’t crumble over time. For mounting bolts, brackets, and other hardware, we use hot-dipped galvanized steel or 304 stainless steel, depending on the application. Even in a standard warehouse, uncoated bolts will start to rust within a few years, leading to loose fans and vibration that wears down the whole system. We learned that lesson early on—our first few clients complained about rusty mounting hardware, so we switched to galvanized hardware across the board, and that issue disappeared almost entirely.
Now, let’s talk about specialty applications, because not all backward centrifugal fans are the same. For extreme environments, like fans used in mining operations where they’re exposed to coal dust and high humidity, or in power plants where they handle flue gas, we use even more robust materials. Impellers here might be made of high-chrome cast iron, which is incredibly resistant to abrasion from heavy dust particles. Housings get coated with a ceramic-based lining, which is way more durable than paint or powder coat, and can handle temperatures up to 1,200 degrees Fahrenheit without breaking down. For fans used in cleanrooms, like semiconductor manufacturing or hospital surgical suites, we use ESD (electrostatic discharge) safe materials—all components are made of static-dissipative plastic or coated metal, so they don’t build up static electricity that could damage sensitive equipment. I recently worked with a semiconductor client who needed 20 custom backward centrifugal fans for a new cleanroom; they specifically requested ESD-safe plastic impellers to avoid any chance of static-related product damage, and we delivered them on time with no issues.
I get it—when you’re buying a fan, you’re not thinking about the specific grade of steel or the type of bearing material. You’re thinking: Will this fan move enough air? Will it run efficiently? Will it last 10 years or 20? That’s why every material choice we make is tied directly to those questions. For example, choosing a thicker gauge housing doesn’t just make the fan heavier—it reduces air leakage, which means you use less energy to run the fan every month, saving you money on utility bills. Choosing galvanized steel instead of a cheaper uncoated steel impeller doesn’t just prevent rust—it means you won’t have to replace the fan every three to five years, saving you on replacement costs and downtime.
At the end of the day, a backward centrifugal fan is only as good as the materials that go into it. We’ve tested dozens of materials over the years, scrapped ones that worked well in a lab but failed in real-world conditions, and stuck with the ones that have proven themselves for our clients. If you’re shopping for a backward centrifugal fan—whether it’s for a small retail exhaust, a large warehouse ventilation system, or a specialty industrial application—let’s talk. I can walk you through the best material options for your specific needs, help you design a fan that fits your budget and performance requirements, and make sure you get a unit that will hold up for years. Don’t settle for a fan made with cheap, unknown materials that will leave you with breakdowns and extra costs down the line. Reach out today to discuss your project, and let’s build a fan that works for you.
AC Axial Fans References:
- ASHRAE Handbook – HVAC Systems and Equipment, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., 2020.
- Centrifugal Fan Design and Application Guide, Industrial Ventilation Division, Air Movement and Control Association International, Inc., 2018.
- Material Selection for Industrial Fans, Department of Materials Science and Engineering, University of Michigan, 2021.
Suzhou Blauberg Motoren Technology Co., Ltd.
Suzhou Blauberg Motoren Technology Co., Ltd. is one of the most professional backward centrifugal fans manufacturers and suppliers in China, featured by quality products and good service. Please rest assured to buy bulk customized backward centrifugal fans from our factory. Welcome to contact us for quotation.
Address: No. 8, Zhu Street, Industrial Park, Suzhou, JiangSu, China
E-mail: Andie@blauberg.cn
WebSite: https://www.blaubergmotors.com/
