Choice of clean room casework, or furniture, is one of the most important decisions made when setting up classified space. Cabinets and associated doors, hinges, handles, panels, benchtops, shelving, and vertical/horizontal surfaces must be compatible with the application and the clean room’s classification by Federal Standard 209E for airborne particulate cleanliness. Surfaces must be as easily cleaned as walls and floors, emit no particulate contaminants, and above all resist exposure to liquids and solids processed inside the room. Since the purpose of a clean room is to protect the environment from hazardous materials or sensitive materials from the environment and humans, or both, clean room casework must fulfill those missions and be environmentally “invisible.”
Most clean room casework today is made from coated steel, stainless steel, and polypropylene. Polypropylene casework has been around for years, remaining a niche product due to its high cost, but Terry Thompson, polypropylene sales manager at NuAire (Plymouth, MN) says polypropylene is the material of choice for clean rooms that use corrosive acids or chemicals or that experience high humidity.
Polypropylene is about 2.5 times as expensive as steel or wood casework and just slightly more expensive than stainless steel. As Thompson explains, “Polypropylene is made from a petroleum product, so we’re at the mercy of the oil markets. But more important, a polypropylene cabinet needs a lot of handling during manufacture— much more than stainless steel… Polypropylene edges are sharp and must be smoothed and deburred, then welded together.”
Clean room casework is normally specified by whoever plans the room, which is either an architect or a company engineer. Owners increasingly ask for modular casework, Thompson explains, because it provides versatility and changeover capability when a clean room’s mission changes.
Outside design firms sometimes over specify for casework, Thompson says, to cover all contingencies. In one instance where polypropylene casework was designated, Thompson called the owner to confirm that the application called for it. “They didn’t realize how expensive it was and wound up ordering a less costly alternative that suited their needs just as capably. If you can get by with metal casework, that’s obviously the way to go.”
Hemco specializes in Class 1000 and Class 10,000 clean room furnishings and installations, a niche that Campbell describes as “clean labs” to distinguish them from higher-class semiconductor processing suites. Hemco has done Class 100 installations, but usually as sub-areas of Class 1000 rooms. Within that marketplace the company sells casework fashioned from welded steel coated with an epoxy powder coat finish. These structures are fabricated as easily as stainless steel but have much higher resistance to acids and moisture. They are also available for about one-third the cost of polypropylene and stainless.
Model #VSW Vertical Sliding Pass Thru Window
- Available in custom widths and heights and is a mere 2-1/4” in depth, taking up very little space
- Also available in 304 or 316 stainless steel with glass, clear plastic, or opaque panels
- Easy to open and is held open by counterbalances tuned to the window weight
- Easily installed within minutes
Compounding Cleanroom USP 797 Compliant
- An ISO 5 (Class 100) primary processing (buffer) area with three HEPA filter/fan units provides a total of 1950 CFM (3315 m³/hr) of 99.99% particle-free air
- Sliding clean vinyl curtain creates a separate antechamber for personnel gowning or product staging
- Stainless steel trim is easily sterilized, and panels stand up to alcohol and other biocides
Series 64 Perforated Stainless Steel Cleanroom Tables
- Allow uniform airflow through the work surface, and eliminate eddies and stagnant air pockets that are on or above the work surface of solid-top tables
- Feature a stainless steel support frame and are ideal for vertical flow cleanroom applications
- Continuous-top and perimeter-frame models are available
Clean Air Products