What Your Commercial Cleaning Services Provider Should Know About Pressure and Airflow
We previously discussed how cleanrooms must be cleaned and their filtration needs. Let’s examine the relationship between pressure and airflow in a cleanroom.
A Pressing Matter
Creating a pressure difference is a popular method for controlling cleanroom contamination by keeping unwanted particulate from entering, floating about, or exiting a cleanroom. This method works based on the concept that having rooms at different pressures controls the direction of airflow between the rooms and, therefore, inhibits the flow of particulate matter. More specifically, creating an area of high pressure by adding air volume reduces the chance that particles from a less-pressurized space can “fight the tide” and make it into the high-pressure room. This is partly because high-pressure (positive) areas create a push effect, almost like a high wind, while low-pressure (negative) areas experience suction similar to when you open a door.
Whether a cleanroom should be positively or negatively pressurized depends on its function.
To prevent unwanted particulate from entering a cleanroom, you want it positively pressurized. Manufacturing electronics and microchips where the smallest particulate can harm the final product calls for positively pressured cleanrooms. If, however, the idea is to keep contaminants from escaping the room, such as in hospital areas caring for highly contagious patients, a negatively pressured cleanroom is required.
The most common way to increase the air pressure in a cleanroom is to add clean, filtered air to the room. This is most often done through the ceiling. Negatively pressurizing a cleanroom usually requires removing air from the room. This is most commonly done by inserting filtered air near the floor and sucking air through filters near the ceiling. In these rooms, all openings must be sealed. The important thing is for all escaping air to be filtered to remove potentially dangerous contaminants, which requires a means of ventilation.
Maintaining Air Quality
Ventilation systems in cleanrooms remove contaminants and help maintain air to the specified cleanroom standard. These systems vary in how they work and costs. We suggest researching and speaking with your healthcare environmental services (EVS) provider or commercial cleaning services company to learn the pros and cons of the various systems. (If your current provider cannot help you, we have 50 years of cleanroom experience in healthcare, aerospace, life-sciences, and manufacturing and are happy to help.)
No matter what system you choose or already have installed, it is essential to ensure it is functioning properly by checking it periodically. Many things can negatively impact it, such as duct build-up, air leaks, worn-out pumps and fans, and old age. If inconsistencies are discovered in the flow, it is important to identify the culprit and fix the problem immediately.
The two most common airflow ventilations systems in cleanrooms are the:
- Laminar flow system. Laminar or unidirectional systems rely on the airflow that moves the air in a uniform pattern in velocity and direction, either laterally or top-to-bottom. For cleanrooms using this system, airflow should be checked at the supply vents and throughout the room.
- Turbulent (nonlaminar) airflow system. This type of system removes contaminants based on a certain number of air exchange rates per hour. The proper functioning of this type of system is checked by measuring the airflow at the supply and return points while calculating the number of air exchanges per hour.
There are many equipment options designed to measure the efficiency of either system. Again, we recommend talking with your cleanroom facility maintenance provider to see which should work best for your system.
Air quality is critical in an enclosed space such as a cleanroom. It keeps contaminants at bay while creating a healthier and more enjoyable environment for workers. The best place to install air return ducts is lower or midrange in a wall. The air from ducts in these locations tends to be fresher, cooler, and cleaner. Ceiling air returns are often plagued by lower-quality, warmer air because of poor air distribution and because hot air rises.
A Healthcare EVS, Commercial Cleaning, and Facility Management Team With 50 Years of Experience
Are you looking to set up or have your cleanroom maintained to the highest standards to keep your hospital, manufacturing facility, or other business running and in compliance? With more than 50 years of cleanroom experience, we can help. Contact us today.