Manufacturers that have traditionally focused on industrial applications might find they need a more controlled environment in which to make parts for medical devices. Cleanrooms provide this environment in part with positive pressure to guard against pulling in contamination from surrounding areas. (Cleanrooms for hazardous products, on the other hand, require negative pressure to contain harmful materials.)

Government standards classify cleanrooms by the number of allowable particles (by micron size) per volume of air. The standards also give requirements for monitoring to prove continued compliance. Many of you may have heard the terms Class 10, Class 100, Class 10,000, and so on, which are the classifications under Federal Standard 209. This has been replaced by ISO 14644, which places cleanrooms in Classes 1 through 9. The two standards are similar, but ISO adds a few classifications and specifies air volume in cubic meters rather than cubic feet.

Selecting a cleanroom is relatively straightforward when a manufacturer is directed to do so by the FDA. In less clear-cut situations, such as when delicate instruments require cleanliness, it's easy for companies to spend too much money trying to be unnecessarily clean or to continue having problems by not being clean enough.

Cleanroom costs depend on its particular classification and can include design and construction, operation, training, on-going supervision, maintenance, cleaning, and testing and recertification, as well as ancillary products such as garments, wipes, sticky mats, and furniture. A few tips will help select the most useful cleanroom. For example:

Look to industry organizations and check out peer groups such as the ISPE — International Society of Pharmaceutical Engineers. They can provide information including FDA requirements and your industry's control baseline. Also, compare the efficiency of your contamination control to that of your peers.

Perform an internal manufacturing audit. This helps cleanrooms work most efficiently by finding contamination sources. Suppose you determine the raw material is dirty. It may make more sense to put the material in a separate area or change how its supplier works rather than handling the material in a cleanroom. An extruder packaging products in a cleanroom, for instance, was supplied rolls on cardboard stems. These measurably contaminated its cleanroom. The extruder had the supplier change the stems to plastic and inexpensively solved the problem.

Determine if temperature and humidity control are required. This is important because temperature and humidity extremes can result in increased product failure and personnel less likely to follow procedures. Several industries publish manufacturing specifications with the temperatures and humidities at which companies must produce products. An example of an application in which temperature and humidity control might be necessary is making plastic pieces for a blood-diagnostic device. Control is critical because end users only get correct blood-test results when the device components are free from moisture.