Cleanroom Recommended Gowning Protocol Dirty Link in the Ultra-Clean Chain?
Manufacturers invest hundreds—even thousands—of dollars per square foot of cleanroom space to meet ISO-proscribed particle counts. Shouldn't the same standards be required of the people who enter and potentially contaminate this ultra-clean environment?
Proper cleanroom garments, including hoods, face masks, booties and gloves, help to contain particles that people emit. Yet improper gowning procedures can negate your investment in cleanliness and threaten yields of sensitive semiconductor devices. Once a garment is contaminated—violated by contact with a dirty surface—it spreads particles everywhere it goes.
Sure, you can train personnel on proper garmenting procedures, but how do you guarantee compliance? A violated garment doesn't set off alarms, and few facilities can afford quality control monitors to supervise every person through every washing and dressing stage. Yet if strict controls are not observed, dirty gloves and coveralls almost certainly will come in contact with clean operations.
A Gowning Area that Supports Clean Protocol
The simplest and most economical approach to this dilemma is a correctly designed gowning area, complete with well-designed change room products, that keeps personnel on a clean track.
This design starts with a room with pressure greater than that of the outside air, but lower than the cleanroom. This cascading pressure differential reduces the opportunity for contaminants to enter each controlled space. It includes a laminar flow of HEPA-filtered air, typically emitted through ceiling filter/fan units. This continuous wash of clean air immediately removes personnel-emitted contaminants, as well as particles present even in cleanroom-laundered garments (see Figure 1). Failure to maintain the desired particle standard in the change area will lead to contaminating clean garments.
Activity
No. of particles (>= 0.3µm)
Person emits during garmenting process
3,000,000/min.
Cleanest skin (hands)
10,000,000/ft2
Employee street clothes
10,000,000 to 30,000,000/ft2
Floor and bench surfaces
> 10,000,000/ft2
Garments supplied by cleanroom laundry
1,000,000/ ft2
Figure 1: Gowning Area Particle Generators Source: Encyclopedia of Clean Rooms, Bio-Cleanrooms and Aseptic Areas, Dr. Philip Austin, P.E., 2000
The Change Room illustration depicts an effective floor plan that places the proper gowning stations in appropriate locations. Although many variations on this layout are possible, they should support these key garmenting guidelines:
Don't Touch! Most cleanliness violations occur when a garment is touched by dirty hands, or when it touches a dirty floor. Hands and gloves should therefore be washed and dried frequently. Select washers and dryers with no-touch IR sensors to minimize the chance of violating gloves. Maintain ultraclean, unviolated surfaces where garments can be donned without contamination. Properly placed gowning benches or use of a special gowning platform helps maintain “not step” areas where a coverall may touch the ground during gowing.
Dress from the Head Down! That way, released particles won't fall on clean garments or booties.
Understand Garment Design! In most instances, gloves and booties are worn over coverall sleeves and cuffs, and hoods are tucked inside collars. Make sure that personnel are trained on how to seal these gaps between clothing, and include a mirror to allow final self-inspection. Hang a photo of a correctly garbed person next to the mirror as a "how-to" guide.
Minimize Motion! As Figure 2 indicates, people wearing cleanroom garments emit thousands of particles per minute even when sitting still! People in street clothes, walking from one change room location to another, release millions of particles. Change room plans should therefore minimize motion, especially during the final stages of dressing, by efficiently organizing the flow of personnel from one station to another.
Minimize Maintenance! Do you have dedicated, trained personnel to peel off adhesive shoe mats, wipe down gowning benches, keep "clean zones" regularly scrubbed, empty waste receptacles, restock garb dispensers, and perform other upkeep with the absolute regularity that your protocol requires? If not, look for ways to minimize reliance on humans—through automation, careful product positioning, choice of materials, and so forth. Initial cost may be higher, but reduced maintenance and greater compliance provide a rich return on your investment!
Train and Reinforce! A good change room design supports proper protocol, but it doesn't teach it. Make sure that personnel complete a formal training program, and stress protocol by hanging reminder posters at every gowning station that reinforce proper procedures.
Personnel Activity
Snap Smock
Standard Coverall
2-Piece Coverall
Tyvek® Coverall
Membrane Coverall
No Movement
100,000
10,000
4,000
1,000
10
Light Movement
500,000
50,000
20,000
5,000
50
Heavy Movement
1,000,000
100,000
40,000
10,000
100
Change Position
2,500,000
250,000
100,000
25,000
250
Slow Walk
5,000,000
500,000
200,000
50,000
500
Fast Walk
10,000,000
1,000,000
400,000
100,000
1,000
Figure 2: Austin Contamination Index Particles >= 0.3µm emitted per minute in garment indicated Source: Encyclopedia of Clean Rooms, Bio-Cleanrooms and Aseptic Areas, Dr. Philip Austin, PE, 2000 Note: Light/heavy movement refer to partial body movements (motioning with arm, tapping toes, etc.). Change of position refers to whole body motion (standing up, sitting down, etc.).
Durable; resistant to corrosion, chemicals/solvents, and rust. Making it the preferred material wherever frequent cleaning and sterilization are required.
Through 40 years of continuous product improvement, Terra has solved problems that other gowning bench manufacturers don’t realize they have.
One-Piece Design with Convenient Bootie Shelves
Stainless steel solid-top gowning benches available with dual perforated shelves for bootie storage.
Many Top and Frame Styles
Solid, tubular, and perforated tops available to accommodate ISO cleanliness and air flow-through requirements; free-standing models include non-contaminating, adjustable nylon feet.
Cylindrical Base: Comfort and Cleanliness
Cylindrical-base gowning benches with rod tops meet the strictest cleanliness requirements for laminar air flow-through and eliminate sharp corners.
Modular Benches Meet Floor Space Needs
Sectional straight and curved gowning bench modules adapt to your space, allowing you to demarcate clean floor where garments may touch without contamination.
Reinforce Clean Gowning Protocol
Gowning Platforms clearly demarcated “no step” area where coverall may touch without contamination (shown with optional CleanLean Rail).
Space-Efficient Configurations
Ideal for small gowning areas with limited floor space! Includes single support leg for easier floor cleaning; opposing end attaches to wall bracket.
Easy-to-Clean Rod-Top Gowning Bench
Rod-style cleanroom gowning benches offer a contemporary design plus reduce surface area to improve laminar air flow and reduce particle build-up. The wide openings also allow the bench to dry more quickly after it is washed down. This makes the thick-gauge rod-top suitable for sterile applications that require frequent wash-downs, such as food-processing or pharmaceutical plants.
Electropolish Finish
Electropolishing increases corrosion resistance and improves ease of cleaning with a smooth, reflective, mirror-like finish. You can see the difference in reflection from the catalog placed on the table.
BioSafe®: Terra's Ultimate Cleanliness Rating
Terra's BioSafe products are designed for life science applications: no gaps and crevices where microbes can colonize, rounded corners for easy disinfection, won't produce contaminants during sterilization, and exceed cGMP, IEST, ASTM and ISO 14644-1 requirements.
Stainless Steel Dual Level Gowning Bench | 1530-35 displayedDual Level Stainless Steel Gowning BenchTerra's Dual-Level Gowning Bench features a seat with foot-rest for applying coveralls, booties and other garb.
Stainless steel solid-top gowning bench with posts for floor mounting | 1530-18-2 displayedFloor-Mounted Stainless Steel Gowning Bench, Solid Top, 3 Posts Gowning BenchStainless steel floor-mounted gowning benches with solid tops prevent floor scratching and help you maintain gowning areas at specified change room locations to reinforce gowning protocol.
Free Standing Solid Top Gowning Bench | 1530-27-2 displayedStainless Steel Free Standing Square Solid Top Gowning BenchFree-standing benches feature non-particulating leveling glides and come with solid, perforated, tube, rod, or slat tops (accommodating laminar airflow inside a cleanroom or change room).
Cleanroom-compliant, aseptic benches for ISO-rated gowning rooms (84" model shown) | 1530-13 displayedGowning Bench; 304 SS, Free Standing, Tubular Top, 72"L x 16"W x 18"H
Removable Bootie RacksRemovable Bootie Racks304 stainless steel removable bootie racks feature easy-clean bootie compartments with perforations to minimize air turbulence
Gowning Platforms feature a clearly demarcated “no step” area where coverall may touch (shown with optional CleanLean Rail) | 9605-49 displayedGowning PlatformsGowning Platforms feature a clearly demarcated “no step” area where coverall may touch (shown with optional CleanLean Rail).
Configurable benches can be used to increase gowning room efficiency by delineating "clean" and "dirty" zones | 9599-00-2 displayedFloor-Mount Gowning BenchesConfigurable benches can be used to increase gowning room efficiency by delineating "clean" and "dirty" zones.