Hunting contaminants: Choosing the right vacuum for your cleanroom
08/01/2007
Defining your cleanroom needs will help make sense of HEPA-filtered vacuum options
By Russ Seery, Nilfisk-Advance America
From pharmaceuticals to semiconductors, cleanrooms are highly regulated environments. Under the International Organization for Standardization’s (ISO) strict criteria put forth in 2001, manufacturers across the board have fallen under a great amount of pressure to keep cleanrooms clean and have been forced to evaluate and improve their housekeeping regimens. The risks associated with failing to do so affect a company’s efficiency, employee health, and, ultimately, the bottom line. So what is the best way to tackle contaminants when the very act of cleaning can affect a room’s ultra-sensitive environment?
Measurements taken in one cleanroom setting found that a dusting system using disposable cloths polluted the space twice as much as a system using a HEPA-filtered vacuum cleaner. Though wipe-down methods are necessary in many cases, vacuuming is often the most efficient method because particles are retained inside the machine with little chance of being exhausted into the atmosphere; however, not just any vacuum will be appropriate. There are many factors to take into consideration when choosing the right vacuum for your cleanroom.
The source
First, it’s important to pinpoint common cleanroom contaminants and how they can be prevented from entering the cleanroom in the first place. Contaminants are typically generated by three major sources: cleanroom personnel, materials, and equipment.
Personnel. Of course, one of the most common-and hard to control-contamination sources is people. While cleanroom gowns and other garments are designed to limit human contamination, it is impossible to regulate uncontrollable actions like sneezing and coughing. The typical working person generates approximately 1 million organic airborne particles greater than 0.5 microns per minute. In instances of human contamination, wipe-down methods are often the best, as they prevent contaminants from even entering the cleanroom.
Materials. Cleanroom consumables-such as gloves, masks, wipers, swabs, hairnets, booties, HEPA filters, and tacky mats-can be a breeding ground for contaminants if the proper preventive measures aren’t taken. For example, if employees do not decontaminate their gloves before entering the cleanroom, everything they touch may be contaminated-including the finished product. The costs of repairing such damage can be exorbitant. Once again, it is vital that all consumables be thoroughly decontaminated prior to cleanroom use.
Machinery. Another potential source of contamination is the equipment already found within the cleanroom. The vibration of this equipment alone is often enough to cause a breakdown of particles, which then circulate in the ambient air.
The most efficient way to prevent this type of contamination is to keep all machinery as dust-free as possible, and this is where a HEPA-filtered vacuum comes into play.
What to look for in a vacuum
When selecting an industrial vacuum cleaner for the cleanroom, many people fail to recognize the key role of the vacuum filtration system. In essence, superior filtration is what you’re shopping for, not just a vacuum, and because available vacuum filter systems are different, it is helpful to know what to look for when choosing the right vacuum for you.
First and foremost, any vacuum cleaner used in a cleanroom must be HEPA-filtered to ensure that 99.97% of all particles down to and including 0.3 microns are collected and retained. In addition, it is absolutely critical that the HEPA filter be installed after the motor to filter the exhaust stream. The motor’s commutator and carbon brushes generate dust, and if the exhaust stream is not filtered that dust will be released into the environment. A word of caution: Not all HEPA-filtration systems are the same. For example, a multi-stage, graduated filtration system uses a series of progressively finer filters to trap and retain particles as they move through the vacuum. The largest particles are captured first by coarser filters; smaller particles are then caught and retained by the finer HEPA filters. This multi-stage system protects the HEPA filters from blockage and excessive wear-and-tear, maintaining peak performance. (When equipped with an ULPA filter, the system should retain up to 99.999% of all ultra-fine particles, down to and including 0.12 microns in size). Additionally, the filtration system in your vacuum should use oversized filters, which slow airflow across the larger surface area and optimize the air-to-cloth ratio. This allows the vacuum to easily collect large volumes of debris over extended periods of time with minimal maintenance.
Besides having an exceptional filtration system, any vacuum used in a cleanroom should be constructed of non-particle-generating materials. For example, non-porous, stainless-steel vacuums-equipped with smooth hoses and attachments-enable personnel to quickly wipe down and decontaminate equipment for faster, simpler sanitization and validation. Many vacuums are also autoclavable, but be sure to check with your vacuum manufacturer first; otherwise you’ll destroy your investment.
Spill response should also be taken into account when purchasing a vacuum. At least one of your vacuums should be capable of wet and dry collection.
Central vacuum systems vs. portable vacuums
Another question manufacturers run into when purchasing a vacuum is whether a central vacuum system or several portable vacuum cleaners will be more efficient. The following pros and cons of both may help ease the decision.
Portable vacuums. Portable vacuums are best for cleaning around work areas where human contamination is prevalent, enabling personnel to effectively clean their area at the end of each shift. Many portables are designed for both wet and dry collection, while central systems are only capable of picking up dry materials. Due to their easy maneuverability, portable vacuums are often used to clean remote or overhead areas that the central systems’ hoses can’t reach.
However, unlike central systems, portable vacuums occupy precious cleanroom space. When purchasing a portable vacuum, look for a compact model. Emptying a cleanroom vacuum can be hazardous, especially when picking up potent compounds. When purchasing a vacuum, look for a unit that comes with a safe collection/ disposal container.
Central systems. The biggest benefit of a central system is that it enables personnel to take collected dirt outside of the cleanroom, where they can dispose of it without any threat to the manufacturing process. Because they are located outside of the cleanroom, central systems free up coveted floor space.
On the other hand, central systems don’t provide the flexibility you need to expand your operation because you may not have the appropriate vacuum capabilities to support a new area. Furthermore, if a contaminant enters the central vacuum system, the whole system may become contaminated-requiring a thorough, costly decontamination process.
Conclusion
Manufacturers must continuously evaluate their housekeeping regimens to ensure that all controlled areas are properly cleaned and maintained. Vacuuming with cleanroom-compatible machines designed specifically to collect and retain microscopic particles enables manufacturers to prevent airborne particulate contamination; ensure air and product purity; and safeguard the health of employees. There are many options out there, but when choosing a vacuum, be sure to know why you need the vacuum and what it will pick up, especially if you are using it to eliminate hazardous compounds. A quality vacuum manufacturer will be pleased to visit your cleanroom in order to assess the situation and match the correct vacuum and filtration system for your application.
Russ Seery is director of sales at Nilfisk-Advance America (www.pa.nilfisk-advance.com).
Tips for keeping your cleanroom contaminant-free
Enlist multiple vacuums. If possible, purchase multiple portable vacuums and assign them to specific critical contamination-control points. Or install a central system backed up by several portable vacuums.
Educate your staff. To ensure the proper use of equipment (and that solid hygiene procedures are practiced), train all employees thoroughly. Don’t focus only on what they have to do, but why-if they are educated as to why certain procedures are necessary they will be more likely to follow them.
Insist on exceptional filtration. A multi-stage, graduated filtration system that filters both intake and exhaust is the most efficient method for capturing and retaining particles. Look for a filtration system that combines this capability with oversized filters for true efficiency.
Maintain equipment. Regularly check and clean all equipment used in the cleanroom, including vacuums and attachments, and replace parts as needed. Staying on top of equipment functionality saves money in the long run by preventing contamination.
Establish a schedule. Develop and enforce a strict maintenance and cleaning schedule that includes a comprehensive vacuuming of the entire facility after every shift.
Select your vacuum system carefully. Seek out vacuums designed specifically for cleanroom applications. Product lines should include essentials like food-grade hoses, cleanroom-packaged vacuums, wet/dry vacuums, and explosion-proof vacuums.