by Environmental Agency
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Indoor Air Quality Basics
Understand the basic science behind your air and contamination control. Below are common standards and concepts used to maintain cleanrooms and controlled environments.
Cleanrooms Are the Cleanest Environments in the World
What is a Cleanroom?
A cleanroom is a controlled area that maintains control over particle contamination as well as other contaminants such as chemicals. Cleanrooms are common in many industries, such as the Pharmaceutical, Medical device, Electronics, Aerospace, Food and Beverage, Optics, Flat Panel and even Automotive.
Why is a Cleanroom so Clean?
Cleanrooms are clean because they filter the air through HEPA filters from 5 to 500 times per hour and they positively pressurize the space to keep unwanted contaminants out of the room. The Environmental Protection Agency (EPA) currently recommends a minimum of roughly 5 air changes per hour in order to keep a room clean.
What is a HEPA Filter?
HEPA is an acronym for "High Efficiency Particulate Air." HEPA is a type of filter that can trap a large amount of very small particles. To qualify as HEPA by industry standards, an air filter must remove 99.97% of particles that have a size greater-than-or-equal-to 0.3um. period, The EPA has stated: “High-efficiency fibrous media filters (e.g., with high MERV or HEPA ratings) and activated carbon sorbent media filters have generally been shown to be the most effective while having the fewest limitations or adverse consequences."
How do I turn my room into a cleanroom like environment?
Step 1: Utilize a certified HEPA filter to remove particulate matter from the room.
Step 2: Positively pressurize the room to keep unwanted contaminants out of the air.
Step 3: Filter the air in the room as many times as possible. The more air exchanges you have per hour through a HEPA filter the cleaner the room will be.
Air Changes Per Hour
Air changes per hour, abbreviated ACPH or ACH, or air change rate is a measure of how many times the air within a defined space is replaced. The higher the filtered air rate the cleaner the air will be and the opposite is true. The lower the rate the dirtier the air will be. The EPA (Environmental Protection Agency) recommends a minimum of roughly 5 air changes per hour. This is critical to understand in order to choose the appropriate air purifier for the size of the room you want to clean.The following chart was taken from the EPA website. This chart is based on the minimum recommended level:
Sound vs Flow
The challenge in air filtration has been balancing the amount of air being output vs the sound or decibel level of the air purifier. The more air that is output the cleaner the room is and the louder the air purifier is. At night most people put their air purifier into “Night Mode” which greatly reduces the amount of clean air being put out and often renders the air purifier ineffective. Revolution by FILTR has smashed the sound barrier and is able to output up to 200 CFM at a decibel level of 51 dB
As a point of reference here is a chart showing various reference sound levels:
Leaves rustling - 10 dB
Whisper – 25 dB
Quiet Office – 40 dB
Normal conversation – 60 dB
Vacuum Cleaner/Washing Machine – 70 dB