Negative cleanrooms pose certain challenges when it comes to maintenance and monitoring. Make sure you understand these 4 points ahead of time.
A negative cleanroom has negative air pressure, which means that the outside rooms have a higher pressure. Negative air pressure cleanrooms are often used when hazardous materials are handled. Negative cleanrooms are subject to the same standards and guidelines as any other cleanroom. However, there are limitations to the ASHP required frequency of cleaning and monitoring negative cleanroom facilities. Some areas of concern are:
- Cleaning of walls and ceiling at least once a month
- Daily cleaning of floors and surfaces
- Monitoring tests at least every 6 months to check for nonviable particles
- Surface sampling
- Electronic sampling
Therefore, anyone who is going to construct one needs to note certain areas in design before, during, and after construction. Here is what you need to know:
- Single wall separation – There are few methods of single wall constriction that are able to withstand pressurization over several cycles of HVAC fluctuation after the initial space test. Wall paint and coatings have the elasticity to maintain adherence without splitting at drywall seams, but wall baseplates and celling-to-wall joints generally don’t maintain tight seals.
- Pressure control – Cascade control is typically used to provide buffers between dirty and clean areas. For a negative cleanroom, the ante room maintains a positive pressure, pumping clean air into the room, bleeding into the cleanroom and pharmacy workroom, buffering the cleanroom from the dirty air in the workroom. However, when the workroom and negative cleanroom are adjacent and pressures fluctuate in these spaces, matter can be transferred.
- Holes and gaps in construction – Negative cleanroom construction can’t maintain a consistent tight seal in the room perimeter. Anywhere conduits, pipes, and network cables are routed through the perimeter wall are sure to result in holes and gaps, making consistent pressure control challenging.
- Low pressure HVAC – Conventional HVACs likely can’t provide sufficient, consistent make-up air pressurization. Most administrators solve this by designing towards the lower thresholds of the USP 797 standard. However, this can result in increased pressure control.
It is important to know these issues, especially for compliance and validation. If you need cleanroom certification or validation, contact Gerbig Engineering Company: 888-628-0056 or firstname.lastname@example.org. Our experts have 30 years of cleanroom experience.