Material Selection and Fabrication Processes for Critical Environments
Stainless steel air distribution components for critical environments, like operating theaters and pharmaceutical manufacturing, must be fabricated following a careful and precise process to ensure performance and cleanability.
This is the case with all air distribution components for these facilities, including HVAC grilles, which direct air flow in such a way as to prevent contamination.
The industry can be a complex one with lots of players, which is why construction project leaders must be careful and diligent in selecting fabricators with a demonstrated history of effective, perfect HVAC components. When it comes to air grilles, accept only the best.
HVAC Return Grille Categories
The form an HVAC return grille takes depends on the needs of the environment and the purpose the grille will serve in an air distribution system. Engineers have created such a variety to withstand specific conditions and perform in ways that keep the people and products in sterile environments as safe as possible.
Stainless steel grilles can come in any of the following types, and more.
- Return grilles with face bars: evenly-spaced, stationary face bars set at specific angles to distribute air.
- Heavy duty return grilles: stationary face bars with extra-sturdy construction.
- Linear light duty return grilles: designed for sidewall or sill installations with fixed airfoil blades running parallel to the piece’s longest dimension.
- Core perforated return air grilles: fit into T-bar ceilings.
- Louvred return grilles: stationary, louvered blades that limit sight into ducts.
- Egg crate grilles: offers a large, open area for return airflow.
- Long-throw return grilles: stationary facebars running either direction.
- Perforated return air grilles: ideal for sidewalks or ceilings.
The Fabrication Process
Critical environment HVAC equipment manufacturers have perfected the fabrication process to produce sturdy, leak-free components that work effectively upon installation. Part of the process that should never be skipped? Leak testing. Even grilles should undergo testing to ensure every welded joint is secure, and louvers or perforations are working as they should to direct air.
Because stainless steel components tend to be made-to-order products, fabricators don’t keep finished stock in an inventory for easy purchase and shipping. They must build components to the exact specifications of the client’s order, following an industry-standard fabrication process. The process takes time, which is why it pays to be proactive when placing your order.
- Laser-cut the stainless steel sheet metal into the right size and shape. The precision of the laser is vital to the final product.
- Place the cut sheet on CNC press brakes to bend them into shape, following specific instructions from a computer.
- Weld each part into place, ensuring seams are air-tight, a necessity for critical environments. A computerized welder or expert human welder completes this step, depending on the type of grille in production.
- Cut each fin on the grille to size, and roll it into shape. Perforated grilles remain flat, and do not need shaping.
- Clean all parts in an alkalized wash cycle, heated deionization rinse, and fresh water rinse. This removes any oil and build-up from the fabrication process.
- Powder-coat or polish each piece, per the order’s instructions. Various finishes are available to blend in with the room, or to complement an architectural design.
- Hand-assemble any remaining parts, and install them on each component.
- Conduct a leak test using a photometer and a leak-proof booth.
- Package each individual item, and ship the completed order to the job site.
Choosing the Right Type of Stainless Steel
Not all stainless steel is created equally. Component makers typically use one of two types of stainless steel for HVAC parts because these perform the best.
Type 304 stainless steel is an austenitic stainless steel containing 18 percent chromium and 8 percent nickel austenitic alloy. It contains more carbon than other types of stainless steel, so it isn’t as easy to weld, but it’s easy to keep clean, in part because of its corrosion resistance.
Type 316 stainless steel is an austenitic chromium-nickel stainless steel with 2 percent molybdenum, that also resists corrosion and heat. It’s easy to weld and fabricate.
Ordering Custom Products
Clean rooms and other critical environments require stainless steel HVAC products, including return grilles, to meet strict requirements and perform properly.
Construction project leaders must collect estimates from multiple fabricators, place an order, and receive the components before they’re needed, so soliciting requests for proposals early on is ideal.
Working directly with a reputable fabricator will result with precision-built products, consistent and functional for clean rooms and sterile environments.