Cleanroom Structure Maintenance

The cleanroom environment is under constant attack by potentially fatal contaminants generated by three major factors: the manufacturing processes that take place within the cleanroom, cleanroom personnel and the endless stream of equipment and materials brought into the cleanroom environment daily.

Cleanroom Structure Maintenance

A properly designed cleanroom staffed by personnel who understand and follow proper cleanroom protocols can keep these particles to near-zero levels. But near-zero levels many not be good enough. Particles travel along air currents in the cleanroom and most are carried back to the air filtration system for entrapment and removal. However, many of the remaining particles tend to settle on or near critical production areas.

Settling particles are affected by numerous physical forces such as static, ionic attraction, humidity, gravity and Van der Waal forces -- to mention just a few -- which cause them to bond to surfaces in such a manner that their removal becomes very difficult, at best. This is where the properly trained and equipped cleanroom housekeeping crew can help.

Personnel training is mandatory

Training is the essential element in developing a good cleanroom maintenance team. Workers must have a thorough understanding of exactly what a cleanroom is and what purpose it serves. Equally important is imparting a knowledge of exactly what it is we are trying to clean and why. Housekeeping staffers do not necessarily need a degree in particle science, but some knowledge of particle size, movement and adhesion qualities is essential if they are expected to perform their duties at the required levels. Without this knowledge, all subsequent training means nothing.

Instilling good personal hygiene habits and teaching the proper gowning procedures are perhaps the two most important aspects of this initial training phase. These should be followed closely by a comprehensive understanding of proper cleanroom protocols.

Only after trainees have mastered the above, should they be introduced to the methodology -- or good science -- of cleaning a cleanroom. This methodology includes defining a list of prohibited materials that must never be taken into a cleanroom and the introduction of accepted cleansing equipment and materials. Proper instruction in cleaning procedures and the ultimate monitoring and verification of cleanliness levels round out a proper cleanroom cleaning methodology.

Equipment selection key to success

The cleaning needs of any particular cleanroom are not necessarily related to the class of cleanroom being serviced. Each case requires individual analysis of not only the cleanroom`s cleanliness requirements (class of cleanroom), but also of the amount and type of contaminants generated within the cleanroom by manufacturing processes and personnel. The gowning requirements of cleanroom personnel must also be taken into consideration, along with the airflow characteristics of the cleanroom.

It is important to note that not all areas within a specific cleanroom will require the same cleaning methodologies and frequency of cleaning. Once the cleaning needs are established, thought should be given to the types of cleaning equipment that should be used in a cleanroom environment.

Vacuums. Most modern cleanroom facilities have built-in central vacuuming systems that allow ease of cleaning and remote disposal of the waste products. These systems can be either dry or wet/dry vacuums. In many cases, fabs are equipped with both types. The beauty of central vacuum systems is the absence of exhaust airflows in the cleanroom itself. There are generally three types of portable vacuums used in cleanroom maintenance: a cleanroom vacuum on which the exhaust air flow is equipped with a HEPA filter, a hospital vacuum on which the HEPA filter is connected to the vacuum`s motor, and a hazardous materials` vacuum in which both the motor and exhaust lines are equipped with HEPA filters.

Portable vacuum systems are used in cleanrooms that don`t have a central system and as a supplemental system for those that do. The selection of a portable vacuum system to fit the task is essential. Most portable vacuums, including some designated as "cleanroom compatible" or as "decontamination units," are not recommended for critical cleanroom use because only the exhaust air flow is usually connected to the HEPA filtration system. In critical use cases, the use of a double-filtered hazardous materials vacuum system is recommended.

It`s imperative to maintain all filters and ancillary equipment for all vacuum systems in proper working order and cleanliness. Ancillary equipment includes hoses, nozzles and other precision cleaning attachments of various sizes and shapes. Equally important is the selection of materials used in these attachments. You wouldn`t want to use a material that could scrape the surface being cleaned, thereby creating additional particle generation.

Portable backpack-type vacuums with the proper filtration systems for both types of exhaust air flow have become a popular choice for cleanroom use. They allow more mobility for hard to reach areas, such as behind process equipment, and in areas such as walls and ceilings where a ladder can be utilized for proper extension.

Although used for many non-hazardous but still critical cleaning operations, the "hazardous materials vacuum" was originally designed for cleaning up wet chemical spills. The recommended procedure for dealing with chemical spills is to notify the facility`s Chemical Safety Officer before anyone attempts to clean up the spill. In most cases, this individual will deal with the problem.

There is always a possibility that housekeeping staff could become involved with a chemical cleanup. Therefore, it`s important that they are properly educated in this area because of the ever-present danger of fire, explosion, and harmful or poisonous fumes. It`s also imperative that your tools -- in this case, the hazardous materials vacuum -- are properly cleaned after each use to avoid any potential chemical incompatibility or harmful reactions during its next use.

It is also important to have a variety of materials available for cleaning up wet chemical spills. Chemical compatibility is equally important and each cleanroom housekeeper should know what products to use with what chemicals.

Mops. Mops and related floor cleaning equipment are perhaps the next most important item in a cleanroom maintenance program. Mop handles are available in a variety of noncontaminating materials, such as fiberglass or stainless steel. Selection is usually based on need; lighter products are best for cleaning ceilings and walls, while the heavier and more durable handles are better suited for floor cleaning applications.

The proper selection of a mop head for specific applications is even more important, however. Mop heads also are available in a wide variety of materials and configurations. Typical examples include sponge mops, which can be self-wringing, and string mops, which typically are made of PVA or polyester fibers.

Routine autoclaving of all mop heads prior to use in Class 100 critical/sterile environments is the only way to stop the introduction of any bacterial contamination into the sterile cleanroom environment.

One other thing about mop heads: In sterile environments, throw them away after just one use. That may sound expensive, but the damage that can result from transferring live bacteria or viruses can be devastating to a company`s bottom line. Also, never take a mop head that was used to clean one area of a cleanroom, such as the gowning area, into another area of the cleanroom, especially from a noncritical area to a critical area. Mop heads are expensive, to be sure, but not as costly as the damage cross contamination can cause.

Wipes. Cleaners probably use more wipes than any other single cleaning product or tool. The most important thing to remember is that selection should never be based on cost. Selection criteria should be based on intended usage, cleanliness, particle-shedding properties, chemical residue of the wiper content, static properties, absorbency and size. It`s important to remember that each specific cleanroom cleaning application may require a specific type of wiper. A wiper manufacturer should be consulted for the best wiper for various applications.

Cleaning materials. The two most commonly used cleaning materials are DI water and isopropyl alcohol (IPA). They are followed by a variety of commercially available floor, wall, ceiling, glass and multipurpose cleaning products.

Some of the major concerns when selecting cleaning materials include:

Product compatibility. Let`s not kill the product.

Process compatibility. Let`s not damage the equipment.

Cleanroom compatibility. Make sure the product can do its intended job, while at the same time ensuring that it doesn`t cause unwanted results. For example, IPA tends to remove moisture from whatever surface it comes in contact with. On unsealed vinyl floors, IPA reacts with the plastercizers and produces a fine, white powdery film that can shed or flake. When walked on, it creates small particle storms that can quickly throw a cleanroom out of spec. IPA also tends to remove paint and can etch plastic and Plexiglas. Despite these examples, IPA is a very popular cleaning material. However, care should be given to its use and applications.

Environmental compatibility. Check all ingredients. Some cleaning detergents have unacceptable levels of sodium, which can damage product and equipment.

One final note on cleaning products: The method of dispensing is very important. Squeeze bottles are preferred over spray bottles or aerosol cans.

Establish cleaning protocols

The Institute of Environmental Sciences preferred cleanroom cleaning protocol can be summed up in three words: vacuum, wipe, vacuum.

Vacuuming pulls loose particles from surfaces. Wiping provides the mechanical energy to remove more tightly bound particles, and cleaning solutions break the surface tensions and reduce adhesion forces. The second vacuuming removes loosened particles and cleaner residues. It is a time-tested method proven to be the most reliable and applicable to most general cleanroom cleaning applications.

The following are recommended protocols for specific cleaning applications:

Ceiling panels. Vacuum with a soft brush attachment. Wipe gently in a single direction using slightly overlapping strokes. Tack roll in a single direction, again using slightly overlapping strokes. Remove spots with a commercial cleaner, DI water and a woven polyester wiper. Vacuum with a soft brush attachment.

Lighting units. Vacuum horizontal surfaces with a soft brush attachment. Wipe surfaces of egg crate light diffusers with a wipe dampened with DI water. Open unit. Wipe bulbs. Vacuum horizontal surfaces with soft brush attachment. Close unit. Wipe trim pieces.

HEPA filtration units. Use extreme caution not to make contact with the HEPA filter. Vacuum with a soft brush attachment. Wipe horizontal surfaces of egg crate diffusers with a wipe dampened with DI water. Vacuum with a soft brush attachment. Wipe trim pieces.

Sprinkler heads. Gently wipe exposed surfaces only with a wipe dampened with DI water. Use extreme caution not to activate.

Walls. Vacuum with a soft brush attachment. Wipe with a wipe dampened in a solution of DI water and a commercial cleaning detergent (mixing solutions and using the appropriate ratio of DI water to detergent will depend not only on the task but also on what is being diluted -- use caution). Wipe in one direction only using slight overlapping strokes. Mop entire surface with a commercial wall cleaning system. Mop from top to bottom using slightly overlapping strokes. Use a minimum of liquid to avoid splashing or dripping. Tack roll from top to bottom. Remove spots with a commercial cleaner and woven polyester wipe. Vacuum with a soft brush attachment.

Glass surfaces. Squirt commercial glass cleaner on woven polyester wipe. Apply to surface with dampened wipe. Squeegee (from top to bottom if on a vertical surface) to remove excess liquid. Wipe with a dry woven polyester wipe.

Piping systems. Use a wipe damped with a solution of DI water and a commercial cleanser. Again, use caution in the ratio of water to commercial cleanser. Wipe in one direction only using slightly overlapping strokes. Wipe top to bottom whenever possible. Use a minimum of liquid on wipes. Vacuum with a curved pipe attachment. Rewipe with a wipe dampened with the diluted cleansing solution to remove spots and stubborn grime. Revacuum with a curved pipe attachment.

Process equipment. Consult with an engineer, a group leader or an equipment operator prior to cleaning any process equipment. Clean only exterior surfaces. Do not clean in or near processing areas. Use wipes damped with a solution of IPA and commercial cleansers -- again use caution when determining the ratio of IPA to commercial cleanser. First vacuum with soft brush attachment, then wipe surfaces in one direction only, using slightly overlapping strokes. Wipe from top to bottom and avoid any splashing or dripping of cleaning solution. Vacuum with a soft brush attachment.

Floors. Vacuum surface. Wash floor with a solution of DI water and a commercial floor cleanser using a clean, non-con taminating mop head. Rinse with DI water and a new, clean non-particulating mop head. The rinse water should be left on the floor long enough to completely saturate any film build-up. Then the rinse water should be mopped up, making sure to change the water after mopping every 10 to 15 square feet of floor surface. The water change is critical to the operation. Failure to change the water on a regular basis can lead to cross contamination, dragging potentially damaging contamination from one area to the next. After the floor is dry, it should be vacuumed with a special HEPA-filtered cleanroom vacuum.

There are a few general rules to remember when cleaning a cleanroom floor, regardless of its composition. Remember the three rules of thumb about what makes real estate more valuable -- location, location and location. The same principle applies to proper cleaning of a cleanroom floor. The three secrets are clean water, clean water and clean water.

For most cleanroom applications, a good rule of thumb is to change the water after washing or rinsing approximately 15 square feet of floor space. In a Class 10 or Class 1 facility, that area should be reduced to at least every 10 square feet, perhaps even more often, depending on the critical nature of the cleanroom use. In some cleanrooms, the water is changed as many as 30, 40 or 50 times for just one floor.

Regardless of what type of flooring a cleanroom has, it is without question the dirtiest and most highly contaminated part of a cleanroom. After all, more than 80 percent of all cleanroom contamination winds up on the floor at one time or another and is then stirred up by foot traffic and put back into the ambient atmosphere. A clean cleanroom starts with a clean cleanroom floor.

Verification procedures

The verification process used to determine if the cleaning crew has done a good job in decontaminating the cleanroom can be as simple as a visual inspection or as sophisticated as present day science allows.

The visual inspection is, by far, the most widely used method. However, it is not nearly as reliable as more scientific methods. The visual method includes naked-eye inspections and the wiping of surfaces with white or black wipes. During naked-eye inspections, the areas being scrutinized should appear as bright as practical. Close attention to hard-to-clean areas must be maintained, and the viewer should utilize oblique angles and oblique lighting whenever possible.

Wiping surfaces with clean wipes (wet or dry) can be augmented with the use of ultra violet lighting, particularly on darker colored wipes and surfaces.

Conclusion

Proper cleanroom maintenance is the cheapest andbest insurance to protect the £1 billion-plus investment required for today`s state-of-the-art cleanroom. It requires a commitment from the CEO all the way down to the most recently hired cleanroom maintenance technician. It is everybody`s job, not just the responsibility of the maintenance crew.

Proper cleanroom maintenance is good science and good sense.

Proper cleanroom maintenance requires the proper selection of equipment.

This Nilfisk GB 726 vacuum cleaner can be used in up to a Class 100 cleanroom, when used with a HEPA filter, or up to Class 10 with a ULPA filter, making it appropriate for pharmaceutical packaging and food processing applications in critical cleanrooms.

A cleaner vacuums the ceiling in a cleanroom to pull loose particles from the surface. Mops are one of the most important items used in cleanroom maintenance.

Routine autoclaving of all mop heads used in Class 100 environments is the only way to stop the introduction of bacterial contamination into the sterile cleanroom environment.

Ian M. Wallis, president of Microcomplete Cleaning Services, Inc. of Newburyport, Mass

Specialization is at the core of our competitive advantage. The cleanroom is where your company earns its money. Cleanroom Maintenance is a critical part of the manufacturing process. If it goes down, production comes to a screeching halt. Proper cleanroom maintenance is essential and your cheapest insurance against potential calamitous financial loss. As the front line defense in protecting your investment, it requires intensely trained personnel, a well-designed cleaning methodology and application specific cleaning tools and materials. Here at Valid8 UK Ltd, we are dedicated to carrying out your specific needs as contracted.

Qualiy services we offer include:

• Decontamination and Sterilization
• Sub floor Cleaning
• Antistatic Sub floor Sealing
• Super Cleans
• Laboratory Cleaning
• Critical Environment Cleaning
• Environmental Tests / Reports
• Wall, Floor and Ceiling Cleaning
• Clean Build Construction Cleaning
• Gown Room Cleaning
• Locker Room Cleaning
• Air Showers Cleaning
• Service Chase Cleaning
• Plenums
• Interstitials
• Protocol Training & Enforcement Services

Staff Training
All Valid8 UK staff have either extensive knowledge and experience within the cleanroom industry or have undergone a course of personal development utilising established industry professionals to deliver the necessary skills.
Valid8 UK Ltd are keen to support the objectives of S²C² and CTCB with a view to ensuring that a professional approach to the maintenance and validation of cleanroom systems is upheld and visable to clients and regulating authorities.

THE SCOTTISH SOCIETY FOR CONTAMINATION CONTROL (S²C²)
THE CLEANROOM TESTING AND CERTIFICATION BOARD (CTCB)

What the Society is and does

The Society was formed in April 1986 to fulfil a need for an organisation which would provide a forum for those who shared a common interest in the provision of clean manufacturing and product cleanliness.

OBJECTIVES

The objectives of S2C2 as laid down in its constitution are:

• To advance the education of the public in matters relating to the practice and science of contamination control.
• To assist in the development of contamination control for the benefit of the public, not only for the advancement of the education of the public but also for the furtherance of their health.
• To assist in the standardisation of effective methods of contamination control.
• In furtherance of the above objectives but not otherwise, the society, in collaboration with the relevant authorities (whether central or local government), industry, universities, technical colleges, schools, technical and professional associations and research institutions shall:
• organise symposia, seminars, exhibitions, lectures and other events for the dissemination of knowledge and experience gained in contamination control
• encourage instruction about the training in contamination control
• encourage research into all matters affecting contamination control
• participate, where appropriate, in the drawing up and monitoring of standards and guidelines about contamination control

MEMBERSHIP RANGE
The membership of the society, which is now over 1,000, has members active in the fields of

• Cleanroom design, construction and validation
• Cleanroom suppliers of contamination control materials or services used in the running of cleanrooms
• Cleanroom suppliers of equipment used in the construction of cleanrooms
• Pharmaceutical & medical devices
• Biotechnology
• Electronics
• Hospital
• Optical
• Semiconductor
• University, research & publishing

NEWSLETTER

The society's newsletter maintains an average of three issues per year and has a circulation in excess of 2,000. It covers current developments and controversial issues in the field of contamination control as well as providing advertisers with a valuable line of communication to a very specialised mailing list.

The Cleanroom Testing and Certification Board (CTCB) has been set up by the Scottish Society for Contamination Control (S2C2) as an education and training initiative to help fulfil the objectives of the Society. It provides teaching and certification for people working in the field of cleanroom technology, and provides information to assist those educating people in cleanroom technology. It is a non profit organisation.

The CTCB offers two courses that are examinable and award a certificate. These are (a) a general course in cleanroom technology and (b) a practical and theoretical course in cleanroom testing. Information about these courses is given below.

Registration

Candidates can register for either of two levels of certification. These are: Professional certification: For people whose profession is cleanroom testing, and who routinely test all aspects of cleanroom testing. These people are examined at the end of the course to see if they have a satisfactory knowledge of cleanroom testing. At the time of their final exam, they will have a minimum of 2 years' experience. If you apply, and have suitable qualifications, you will be required to Study the self-study course notes that will be sent to you, attend a lecture course, and then pass a written examination on Cleanroom Testing;

• Attend a one day course on practical aspects of filter integrity and air volume and velocity testing, and hence be prepared for the practical exam;
• Pass a practical exam by demonstrating a high level of competence in (a) filter integrity testing and (b) measuring air velocities and volumes;
• Candidates who successfully pass the written and practical exams will be awarded a Professional Certificate.

Associate certification: For people who are familiar with aspects of cleanroom testing and wish to gain a fuller knowledge of the subject, or, have been working less than two years as a cleanroom tester, and wish to use the certification course as a basis of training to work towards professional status.

If you apply for the associate course, and have suitable qualifications, you will be required to:

• Study the self study course notes, attend a lecture course, and then pass a written examination;
• Attend a one day course on practical aspects of filter integrity, air velocity and volume measurement;
• Candidates who successfully pass the written exam will be awarded an Associate Certificate.

The written exams are identical in both qualifications, the difference between the two certificates is that professional candidates will have 2 years experience and are examined on their practical competence. In the associate qualification, the practical aspects will be taught, but not examined. Students who obtained the associate qualification may convert to a professional certificate once they have a minimum of two years experience, but they must pass the practical exam.

On registration, the candidate will receive self-study course notes, a questions and answers handbook, an example of a written exam paper, and notification of the date of the next examination. Prior to attending the course and exams the professional candidates will be sent information on how the practical exam is run and the CTCB expectations.

On satisfactory completion of the course, candidates receive a CTCB certificate, and are entered onto the CTCB 'List of successful candidates'. This registration applies to the person who passes the exam, and not their firm. A professionally-certified person will remain on the list for 5 years, at which time they must be re-certified.

The Course Notes and Syllabus

The candidate will receive over 100 pages of course notes. Also issued is a handbook containing a set of questions (and answers) for each topic in the notes, so that the candidate can assess their knowledge. The syllabus of the course is as follows:

• Introduction to cleanroom testing;
• How a cleanroom air conditioning plant works;
• High efficiency air filters;
• Standards for classification and certification;
• Air supply and extract volumes;
• Differential pressures;
• Containment, visualisation and recovery tests;
• Air filter integrity tests;
• Particle measuring methods according to ISO 14644-1;
• Microbiological measurements;
• Cleanroom conduct.

Revision Lectures, Practical Training and Examination

Candidates for the professional certification will attend for three days and receive practical training, a lecture revision course and sit practical and written examinations. The Associate candidates will attend for two days and receive practical training, a lecture revision course and sit a written exam. These days will be structured as follows:

First day: Practical training
Second morning: Revision lecture course
Second afternoon: Theory written exam
Third day: Practical exams (only for professional candidates)

The days will be organised as follows: First Day Practical Training: This course will cover:

• Filter integrity testing. Information will be given on an aerosol smoke generator and photometer, and how these are used to test filter integrity. The technique will be demonstrated and each student will have an opportunity to use the method.
• Air velocity and volume flow measurement. Information will be given on how to carry out testing using a anemometer, hood capture method, averaging pressure flowmeter, and Pitot-static tube. The techniques will be demonstrated and there will be an opportunity for each student to use the methods. Second Day Revision Lecture Course: A morning is spent at a lecture course revising the course notes.

Second Day Theory Exam: This will examine the candidate's knowledge of the course notes. The questions will be short and of the type that can be answered by no more than 10 words; no essays are required. The questions will be similar, or identical, to those given in the question and answers handbook. The pass mark is 50%. Third Day Practical Exam: The professional candidates will be examined on their competence to carry out the following important tests:

• Determine the average air velocity and uniformity, as well as the volume of air passing through a HEPA fan/filter unit by use of an anemometer. Measurement by use of the hood capture method must also be demonstrated.
• Demonstrate that they can operate a smoke generator and photometer to find leaks in a filter and filter gasket.

The candidate will be required to competently write up reports on the results of the two tests. The candidate's exam results are assessed by an Examination Board drawn from the CTCB Advisory Board.  It is anticipated that about 70% of the candidates will pass their exams in the first attempt. The CTCB has an examination appeals procedure. Anyone failing an exam can re-sit it at the next examination. This can be done in the UK, or at another CTCB Cleanroom Testing certification course in Ireland and Sweden.