We often take for granted the interdependent complexities of a normally operational cleanroom. Clean air systems and other support facilities generally operate continuously. The extent and nature of how those systems normally operate depend on whether the cleanroom is occupied continuously or by shift so facilities are appropriately scaled down to reduce expenses.

Sometimes extended shutdowns are planned to repair, renovate or deep clean cleanroom facilities. Such events are planned in advance and carried out in a controlled manner.

However, non-standard or other sudden disruptions can occur without notice, seriously affecting normal operational activities. There are myriad causes for non-scheduled disruptions that can impact the integrity of cleanroom air cleanliness, product and processes integrity, research and other activities.

The IEST Contamination Control Division formed Working Group 041 to develop a recommended practice that identifies the root causes of sudden serious disruptions in cleanrooms and recommends effective recovery methods. The working group met for several years collecting and describing causes. However, the diversity in construction, application and normal operation of cleanrooms would require varied methods of restoration for each type of disruption. The group decided such a comprehensive document wasn’t practical.

Instead, the working group determined it’s best for cleanroom managers and operators to plan for their own likely disruptions to their facilities. They should identify and perform a risk assessment of disruptions given their facility type, location and other factors. They also should document standard restoration procedures to return their cleanroom to environmental operating conditions for each identified type of disruption.

As a result, the working group developed a new Recommended Practice: IEST-RP-CC041: Planning for Recovery From Disruption to Cleanrooms and Other Controlled Environments. It provides an extensive list of various disruptions that may affect cleanrooms in general, the resulting contamination and other failure effects to expect. Table 1 contains a matrix of possible causes for a disruption and the systems likely to be affected by the event. Table 2 is a matrix of failure modes and possible contamination and other failure effects.

This recommended practice allows cleanroom managers and operators to create their own list of possible risks for disruptions and develop strategies and actions so that they can put into action an organized and efficient recovery activity.

The ability to quickly assess the full effect of a disruption to the cleanroom and implement the proper course of corrective actions is critical in minimizing its effect and restoring the cleanroom space to normal operations. Cleanroom managers and operators who use this recommended practice (IEST RP-CC041) can sleep at night knowing emergency plans for unplanned disruptions are fully developed and personnel are ready to act on those plans and return the disrupted cleanroom to full operation with minimal losses.