Improving the Cleanliness of a Cleanroom

Submitted by Brian Sullivan, Frank Schollmeier, Tim Tritch || Valin Corporation
on Wed, 11/21/2018
Depending on the industry and specific environment, different rooms will have different cleanroom classification requirements. There is a litany of information out there regarding how classifications are tested and determined, but not as much about how to improve a specific room’s classification ranking.

The key is that there is not one, catch-all solution to improve a cleanroom’s rank. The most effective way to make this improvement is through a multi-disciplined approach.

This particular discussion will outline three different areas in which a cleanrooms classification can be improved.


Equipment

For years, workstations and shelving systems, often found in cleanroom environments, have consisted primarily of painted stainless steel.

Unfortunately, painted stainless steel can be ultimately harmful to the rating of a cleanroom. When a painted surface such as this is added to a controlled environment, it can easily become a detriment to cleanliness. Due to the vapor that the paint itself can exude, the presence of paint can contaminate certain materials or processes the cleanroom was designed to conduct. Secondly, it can flake or chip over time and cause particle generation. If it is struck hard enough with a tool or instrument while a cleanroom is in use, it can cause gross contamination.

Paint also has the tendency to absorb cleaning agent residue and then later release that cleaning agent in an uncontrolled fashion. Furthermore, it can store the residue to the point where it becomes slick or sticky. It may also interact with cleaning agents and sterilants in a way that prevents an optimal end result.

A better alternative would be to use workbenches, workstations, shelving systems, racks, and carts that consist primarily of extruded aluminum. Aluminum framing systems for cleanrooms do not need to be painted. They will also not corrode or contaminate the environment the way painted stainless-steel surfaces potentially can.


Filtration

A contributing factor to a cleanroom’s rating is the air quality. Effective air filters are crucial to keeping the particulate in the air to a bare minimum and prevent contamination.

Specifically, high efficiency particulate absorber (HEPA) filters are designed to provide the highest level of air filtration available for a cleanroom environment. Whether for a hospital, commercial, industrial or semiconductor cleanroom, the goal remains the same: the best quality filtration possible.

The question that needs to be asked is, “What is being used in the cleanroom for air filtration and what is needed?”

HEPA filters are rated at 0.03 microns and come in four different efficiency ratings and two materials of construction. The standard versions are produced from submicron glass fibers rated at 0.03 microns with 99.97 percent, 99.99 percent, and 99.999 percent available efficiencies.

For the ultimate performance, one can use polytetrafluoroethylene (PTFE) membranes for the filter media with a 99.99995 percent efficiency at 0.03 microns.

One of the key advantages of using a PTFE membrane is that they have smaller pore sizes than micro-fiberglass, allowing for better efficiency.

Another key characteristic of PTFE is that it reduces the levels of off-gassing impurities typical in micro-fiberglass. The PTFE HEPA filters are the ultimate in cleanroom air filtration.


Cleansing Systems

One of the most important functions of cleanroom maintenance and improvement is the process in which it is cleaned. Residue is the main obstacle to contend with here. There are fogging and cleansing systems available that eliminate any contaminants and minimize resulting residue in the aftermath.

The best practice is to utilize a sterilant or disinfectant that is compatible with all common cleanroom surfaces including counter tops, walls and floors. Minncare is a specific sterilant that has superior sporicidal, bactericidal, fungicidal, mycobactericidal and viricidal activity that does not produce hazardous or volatile vapors. This keeps employees and facilities safe.

Minncare also leaves no residual on surfaces. Furthermore, because Minncare is biodegradable and listed by the EPA as environmentally friendly it is easily disposed of — thus keeping the environment safe.

To improve the classification of a specific cleanroom environment, it is important to take a multi-disciplined approach. One must look at the nature of the equipment inside of the room, the sophistication of the filtration system, and the type of cleansing system used.

Once analyzed, one can take the necessary steps to improve these areas and ultimately improve a cleanroom’s classification.

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