Using Air Showers in Cleanrooms

There are many different components to a cleanroom that keep particulates out of the air. Among them are garments. While workers must wear special garments to protect cleanroom material, the garment is often not enough. Air showers are used to clean gowned personnel before entering a workspace and after leaving a hazardous workspace.

An air shower is a self-contained air recirculation system installed at a cleanroom entrance. There are doors on either side of the shower, and they cannot be open at the same time. An employee enters the air shower area and stands in front of the nozzles or slots of the shower. Class 100 filtered air blows at high-velocity streams onto the employee. As the employee raises his arms and rotates in place, the flapping effect the air has on his clothes “scrubs” particulates from his garments. After 4-8 seconds of cleaning time, the employee waits another 2-4 seconds for the system to purge the contaminated air.

Air showers can be designed to clean one person at a time or many. To clean many, the shower system is built as a tunnel. These tunnel-like systems are beneficial for shift rotations of 30-40 people.

Using air showers not only keeps debris from entering a cleanroom, it also keeps buildup of particulates low so that cleanroom maintenance is required less often. Energy consumption is also less because the HEPA filters don’t have to work as hard; the filters also last much longer when employees use air showers.

There are several designs to consider when choosing an air shower. The size and setup of the shower (where and how nozzles are placed) depends on space and facility requirements. Most air shower systems are modular. The materials are made from stainless steel, painted steel or laminated particleboard. The cleanroom environment will determine which material is best, though the particleboard is a less reliable, economic option that is not appropriate for many environments.

Finally, there are two sets of filters. The pre-filter is used to catch the bulk of the contaminates. The second filter is a high-capacity, 99.97% efficient HEPA filter.

According to Kevin Weist’s article “Air Showers” in Controlled Environments, these are your major considerations when choosing an air shower system:

  • “System should be modular, allowing for easy configuration, shipment, and assembly
  • Shell should be made of stainless or painted steel
  • Blower system must supply high velocity, high volume air
  • Recirculating filtration system should use pre-filters, followed by high-capacity HEPA filters
  • Units should have a high number of adjustable, evenly spaced air nozzles
  • Unit should have magnetic door interlock systems with appropriate controls”

Air showers are incredibly effective at removing particulate and making cleanrooms even cleaner. Their effects also lower maintenance costs and energy consumption. They are wise investments for facilities using cleanrooms.

How Does Outdoor Humidity Affect the Cleanroom?

integrated_workstations.jpgOne of the most costly and important factors in building a cleanroom is air control. Cleanrooms are pressurized and use advanced filters that remove contamination-causing particulates. These airborne contaminates are not the only environmental issue in the cleanroom, though. 

Humidity control is of the utmost importance in a cleanroom. Too much humidity can encourage bacteria growth. Additionally, some products made in cleanrooms, like sutures, are moisture-activated and can start to degrade if the humidity is too high. Too little humidity can cause static electricity. Static electricity is a major issue in cleanrooms, especially those for electronics. Electrostatic discharge can render some parts useless. Also, accidental static shocks to humans can distract workers (and they can hurt!) 

Outdoor air has a direct effect on the humidity level in a cleanroom. Finding the right equipment to adjust for this can be difficult. Many states experience weather that is both humid and below freezing, depending on the time of year. This means that air filter systems for these locations have to be able to both cool and heat air from the outside as it goes into the building. Whether the air is hot or cold, temperature control can cause a number of problems, including coil ice that can melt and cause water damage. 

As sensors detect changes in humidity, the system will turn on and off accordingly. This often creates an uncomfortable situation for the cleanroom workers. Many cleanroom workers complain that the room is either too humid or not enough; there is no happy medium. 

Discomfort in the cleanroom is a distraction for employees. Mental faculties suffer when a person is stressed by humidity. Attempting to adjust controls to fix the problem just makes it worse. The controls are set to ensure the humidity is within a safe range, so changing them can be dangerous. 

As a result of this challenge, there are many products and systems on the market to help with temperature and humidity control. They can be quite costly, so it is imperative to know the needs of a particular cleanroom as well as future budget estimates when researching the right control system.

Developing your Internal Audit of the Cleanroom and Controlled Environments

certification_1Customer and registration audits can be stressful, and even more so when a company questions its preparedness. By issuing several internal audits throughout the year, these second and third party audits will be more successful. Additionally, employees will be better experts in policies, procedures, and instructions. 

Jan Eudy wrote a thorough article on the topic for Controlled Environments called,  “Audit for Compliance.” Here is a summary of considerations when preparing an internal audit. 

  1. Know what and how to audit. Eudy writes: “Internal audits should cover the full spectrum of the company’s processes and be designed to close the loop between the industry’s standards, customers’ specifications, and the company’s people, processes, and product.” Previous audits, including internal audits, can serve as guidelines for which areas to pay the most attention to. Auditors will also focus on what has changed since the last audit. 
  2. Establish and educate a cross-functional audit team. Eudy says to “train them in the company’s audit procedure, policies, and specific elements of the standard relative to the third-party certification.” Develop checklists for the team to use. These help train employees and ensure consistency. 
  3. Evaluate corrective action reports. Identifying trends can help auditors get to the root cause of non-conformance events. Solving the issue in this way ensures that the events will not be repeated. 
  4. Schedule the audits. Scheduled audits are preferred over spontaneous audits. 
  5. After performing the audit, write an audit report. “This audit report should recognize areas that are meeting customer specifications and areas that are compliant with company’s policies and procedures, and industry standards. Internal audits should also focus on opportunities for improvement and can be reviewed in the next scheduled internal audit when documented” (Eudy). The report should be presented at regular review meetings in which management – including senior management – and representatives from all areas of the company are present. 

Once an audit is complete and reviewed, findings will be used to make corrections and offer information for future internal audits. Remember to be consistent with the procedure and the message for the employees’ sake. As Eudy says, “It is important to keep all personnel and departments focused on the same objective—creation of a climate of performance excellence and successful second and third-party audits.”

When is a Modular Cleanroom the Best Option?

Delta industrialAs cleanrooms continues to evolve, standard cleanrooms are not always the best option anymore. Many companies are finding that modular designs best fit their needs. Modular cleanrooms offer more flexibility, little disruption, and they often cost less than a conventional cleanroom. However, they are not always a fit. Here are some pros and cons to this alternative. 

Pros

One of the best features of the modular cleanrooms is that they allow for flexibility. They can be built almost anywhere, disassembled and reassembled, redesigned, and moved from one location to another. This is especially beneficial for companies that plan to expand. As a company’s operations grow, the cleanroom can change size and shape or just be relocated as necessary.  

In saying the structures can be built anywhere, think parking lots, underground laboratories, and adjacent to existing cleanrooms. According to MaryBeth DiDonna’s article, “Building the Case for Modular Cleanrooms” in Controlled Environments, Intel required a “plug and play” cleanroom that “had to be able to be in a parking lot and still have all the infrastructure built into that room.” 

As for underground facilities, Black Hills State University recently announced plans to build a new underground laboratory. Controlled Environments posted the press release, “College to Build Underground Campus and Cleanroom.” The article states, “The Underground Campus will include a cleanroom that allows students and faculty to conduct a variety of research projects including low-background counting physics experiments. The Campus will also accommodate other experiments such as biology and geology and provide storage for equipment.” 

Small modular systems often don’t require professionals to assemble them. They are pre-designed and can be pre-fabricated so facilities can build the cleanrooms themselves. Additionally, they can be constructed without disrupting the daily processes of the businesses that are building them.  

To round it all out, these process-compliant modules are energy efficient.  

Cons

Probably the biggest disadvantage to the modular cleanroom is its length limitation. A typical modular system spans about 20 feet. When it has to cover more space than that, a column needs to be in the middle of the room. This won’t be amenable to a space that has a large piece of equipment where a column would need to go. In some cases, a cleanroom manufacturer can specially design a system to accommodate this scenario, but it may not be cost-effective.  

Other potential downsides may be present with window and door specifications. There is no one-size-fits-all option with the modular cleanroom. Room pressurization, traffic patterns, and direction of the door’s swing are all considerations that can present a challenge with the modular design.  

While the list of pros presented here is longer than the cons, the decision really depends on the application. Consult a cleanroom manufacturer to discuss whether a modular cleanroom is right for your facility.