Since their invention in the 1960s for assembling delicate aerospace equipment, cleanrooms have become important tools in the medical industry. The enclosed areas allow a controlled level of airborne particles generated from cleanroom personnel, tasks, facilities, and equipment. In fact, government standards rate cleanrooms by the number of particles per cubic meter at a specified particle size. For example, room air might contain 293,000 particles greater or equal to 5-µm in size, equivalent to an ISO Class 9 cleanroom. On the other hand, an ISO Class 1 cleanroom contains no particles greater or equal to 0.3 µm. For reference, 5-µm is about 0.0002 in. The diameter of a human hair is about 0.003 in. Particle levels are usually tested using a particle counter. Some cleanrooms also control humidity, temperature, or pressure.

The facilities range in size from entire manufacturing facilities to portable enclosures. Recent rooms are typically modular and flexible, easily collapsed and reassembled in other locations.

Rooms also range in requirement, depending on the application. For example, consider cleanrooms for medical devices and those for pharmaceutical drug mixing. “Both industries are governed by FDA rules,” says Raj Jasiinghani, CEO of cleanroom manufacturer Technovation Systems Inc., Midlothian, Va., (cleanroomsys.com). “But for biotech and pharmaceutical industries, Current Good Manufacturing Practice (cGMP) guidelines are strictly enforced and require validation. But requirements for most medical devices are more relaxed and validation is not as stringent,” he says. In general, recent trends he sees in cleanrooms are energy efficiency, airflow modeling, close monitoring, and risk reduction.

Cleanroom clothing is changing as well. Today's clothing is typically tested for particle generation, particle filtration, and resistance to wear. Personnel working in cleanrooms must often wear special masks, gloves, and the always fashionable “bunny” suits. Here are a few ways companies that manufacture cleanrooms, clothing, and components have updated their products.

Modular cleanrooms

Cleanroom designer and manufacturer Clean Rooms International Inc., Grand Rapids, Mich., (cleanroomsint.com) says it develops innovative ways add clean air to cleanrooms, extract contaminants from them, and more. The firm builds a wide variety of products for isolating R&D or medical-manufacturing tasks. Products range from individual workstations to complete isolation systems.

For example, the Legend line of modular cleanrooms feature a clean, appealing design using aluminum-framed hardwall panels with a durable white finish. Wall panels can be made in custom sizes for entry areas, gowning rooms, and air-locks, to ensure the cleanroom pressure remains constant. Extra-high wall panels accommodate large equipment requiring ceilings higher than the standard 8 feet. Windows are flush-mounted and assembled inside the firm's own cleanroom.

Several models draw ambient air into the fan-filter unit at ceiling level. Filtered air passes into the cleanroom and is then transferred out through air grilles at the bottom of the walls. Recirculating cleanrooms work well in applications that require temperature or humidity control. Air-conditioned air from a plenum is drawn into the fan-filter unit, then passes into the cleanroom. Air from the cleanroom is forced into the air grilles and pushed back to a plenum to complete the cycle.

The company says three factors determine which wall system to use for load-bearing cleanrooms. The first is the amount of total weight on the cleanroom wall. The second is the span or distance between all four cleanroom walls. And the third is the wall height.

In addition, the company's storage cabinets provide flow-through air that the firm says keeps contaminated particles from settling on garments and supplies while in storage. Models are available for garments, with shelves for supplies, or a combination. Units come with replaceable HEPA filters that boast a 99.99% efficiency, capable of removing particles 0.3-µ dia. and larger. The cabinets come either 2 or 4-ft wide and are raised 4-in. off the floor.

Cleanrooms latch together

Cleanrooms from Liberty Industries Inc., East Berlin, Conn., (www.liberty-ind.com) feature a lightweight design with a latching system that makes it simple to attach panels together. Rooms are expandable, with sizes determined by the number of connected 4-ft-wide panels. Standard roof panels come 4, 8, or 12 ft-long. Options for HEPA filter or drop-in light-fixtures openings are available. Panels consist of anodized 6063-T6 aluminum frames with sealed-in acrylic panels. Window panels are clear 1/8-in. Plexiglas.

The company also provides air showers for cleanrooms. For example, a model intended for maximum contamination control features a dual airflow system that removes surface contaminants as well as dust and other particles located in cleanroom clothing folds. A single HEPA-filtered air hose attaches to a fitting located on cleanroom garments. Air blowing into the suit causes it to flutter and force out contamination. The blower includes a 3,450 rpm, 1-hp motor fitted with a high-pressure aluminum radial blade. Showers feature heavy-duty anodized doors with 3/16- in. safety glass.

A colorful cleanroom

White is usually associated with cleanrooms. How boring. To complement corporate branding, Travis Clean Air (TCA), Denver, Colo., (traviscleanair.com) provides modular, portable cleanrooms that come in red, orange, dark green, and six other colors. Rated at ISO Class 7, the units are easy to assemble on site. They feature large viewing windows and an optional pass-through for transferring medicine and devices.

In addition, TCA's custom acrylic cleanrooms target firms needing a dedicated area for compounding pharmaceuticals and ensuring sterile medications. The cleanrooms' clear walls let pharmacists watch the entire pharmacy while they work. A heavy-duty grid supports the cleanroom ceiling, HEPA filters, and lighting. The rooms are ISO 5 to 7 certified and support the USP 797 standard for aseptic processing taking place in hospital and other pharmacies. USP 797 is increasingly being adopted by State Pharmacy Boards.

HEPA filters and more

Filters are a key component of cleanrooms, so it's no surprise they come in a variety of designs. One supplier, CleanAir Solutions Inc., Fairfield, Calif., (cleanroomspecialists.com) provides HEPA units for hospital isolation rooms, surgery suites, pharmaceutical compounding, and biotech and medical-device applications. For example, electrically enhanced filtration (EEF) units charge particles and bacteria with an ion flux inside an ionizing field where the bacteria are killed upon entry into the grid. The remaining particles are efficiently filtered, according to the company — down to 1% of the penetration of conventional filters with the same pressure drop and flow rate.

In addition, the company says its fan-powered air-filter modules make a good substitute for terminal air-filtration units because of their flexibility and ease of installation. The company's Sam MicroSound NCR unit includes quick-release latches for quick replacement of the air-filter media. Room-side power-indicator lights indicate that the cleanroom air-filters are running.

Finally, Airlink Control Systems are intended to control EEF units from a remote console or panel. The equipment lets operators increase or decrease airflow to a selected area as well as use the set-back feature during off-peak hours for lower operating costs. The system uses 115 or 277-V motor blower-units, eliminating the need for high-cost dc motors.

Online cleanroom catalog

An online, interactive catalog from Kimberly-Clark Professional, Neenah, Wisc., (kimberly-clark.com) lists the company's Kimtech brand of products for lab procedures and cleanrooms. Press the Contents button on the toolbar and select, for instance, Eye Protection. The digital catalog pages “turn” and with a “flipping” sound. Pages are full of colorful images of health personnel wearing cleanroom products from the KleenGuard line of eye protection. Tables list part numbers, eyeglasses' color, number of pairs in a box, and the like. For another example, under Gloves, select Kimtech Pure G3 Acid Gloves. Other products include wipers, dusters, and benchtop protective covers.

How to rate cleanrooms

Class	Maximum particles/m3						Fed Std 209E equivalent
	≥0.1 µm	≥0.2 µm	≥0.3 µm	≥0.5 µm	≥1 µm	≥5 µm
ISO	10	2
ISO 2	100	24	10	4
ISO 3	1,000	237	102	35	8		Class 1
ISO 4	10,000	2,370	1,020	352	83		Class 10
ISO 5	100,000	23,700	10,200	3,520	832	29	Class 100
ISO 6	1,000,000	237,000	102,000	35,200	8,320	293	Class 1,000
ISO 7				352,000	83,200	2,930	Class 10,000
ISO 8				3,520,000	832,000	29,300	Class 100,000
ISO 9				35,200,000	8,320,000	293,000	Room air
The table lists cleanroom Classes by the allowable number of particles per cubic meter at a specified particle size.