Another excellent event. Many ‘old’ friends were seen and several new faces introduced-the world of contamination control looks healthy.
Over 200 delegates, from a range of spheres of contamination control, attended the sessions over 2 days.
The format of the conference was based around a workshop theme which considered some of the critical issues that must be faced in order to run a successful cleanroom.
The key areas looked at were cleaning, clothing, training and monitoring.
Each workshop was led by an experienced team and it was due to their skill that such lively and rewarding debates took place.
The society would like to express a great thanks to all involved.
It is clear from witnessing the great interest shown in these basic issues that S2C2 and the Monitor have an important role in supporting the membership. This fact has not been lost on the editorial team and the Monitor will revisit the workshop themes in future issues. But without further ado ……………….
CLEANING AND DISINFECTION
CLOTHING AND DISPOSABLES
TRAINING AND DISCIPLINE
MONITORING A CLEAN ROOM
The discussion included in general the following problem areas:
The discussion was in particular centred around particles adhering to surfaces, the structure of different materials, cleaning method versus contamination load, and methods for controlling cleaning and disinfection.
When choosing method for cleaning you have to consider the actual surfaces of the cleanroom with almost microscopic abilities. An apparently smooth and even surface is seen under a microscope as a roller-coaster landscape. A glossy stainless steel slab contains many treacherous valleys where particles and maybe even grinding residues can hide. To get hold of them can be difficult unless you apply the correct cleaning methodology.
To reach these particles, collect them and dispose of them, only water or alcohol based tenside solutions will do. They can penetrate porosities due to their moisturising properties. When there are extremely high demands for surface smoothness, as for example in the manufacturing of micro-electronics, the working surfaces are mostly electro-polished stainless steel; expensive but necessary.
When cleaning cleanrooms and their equipment, there is generally a distinction made between cross cleaning and decontamination. Unfortunately there is a demand, sometimes too often, that one single method shall be able to handle both cross cleaning and decontamination, irrespective of contamination load. Cross cleaning in cleanrooms should actually only be used at relatively long intervals. With the correct working technique and discipline the cleanliness shall be maintained through regular decontamination, ie precision cleaning and disinfection.
For cross cleaning simpler and maybe cheaper tools and utensils are used. In the case of the latter specially designed swabs and mops, having in themselves a low particle count and to a certain extent moist adsorbing properties, are used. The initial cost for these can seem high, but used in the right way they have a very long life. In severely contaminated areas you should in the cleanroom environment in particular focus on cleaning before you apply cross cleaning or decontamination.
Another problem discussed was that certain disinfection chemicals in themselves act on surface materials, leaving spots that are difficult to remove. This is a recurrent problem preferably solved preventatively, ie at construction level or when the processing schedule is made. Careful selection of the chemical can also reduce the problem.
This discussion centred around methods that directly and automatically measure surface cleanliness. This is a frequent problem area, which some people claim to have resolved. However, the simple methods will be still used for a while, such as intensive light, long wave UV light, contact plates and swab technique when controlling surface cleanliness.
With the light from a 100W halogen lamp you can discover particles down to approx. 10-15m m size. Pick a certain surface unit as a control surface and count the visible particles. This is a method that is simple and can serve as a 'go–no go' test.
With long wavelength UV light, 365nm black light, you discover particles that contain organic matter as they fluoresce. These could be nutrition for micro-organisms.
By first examining the surface by UV light before using the slower analysis method with a contact plate or a swab, you can avoid unnecessary testing. A surface containing fluorescent particles after cleaning and disinfection should not be considered clean. It would not be worthwhile testing with contact plates or swabs until after repeated cleaning.
The discussion also dealt with the problem of a better testing technique than using contact plates and swabs makes possible. The problem is actually that there is great uncertainty as to how deep the plate or swab penetrates the surface you want to examine. It might be that you only catch 10-20% of the actual number of micro-organisms. Unfortunately the participants of this discussion were unable to find a solution to this problem. It could also be of some interest to mention that the coming ISO standard on Biocontamination - Cleanroom only recommends the method with contact plates and swabs for collecting micro-organisms when controlling the cleanliness of surfaces.
Several topics were raised regarding wiping materials, mops, documentation paper, economics and test methods.
Many delegates were unaware that the Institute of Environmental Sciences & Technology in America has published several Recommended Practices dealing with the testing and evaluation of different items of cleanroom paraphernalia, such as wipes, garments, swabs, gloves, etc.
It is possible to obtain very clean wiping materials without having to resort to edge-modified, laundered, knitted wipers, all of which are quite expensive. Wipers are available which are as clean, or even cleaner, than the high-price items, at substantially lower cost. A non-woven wiper made from a mixture of polyester and rayon is an excellent choice in any solvent. Another non-woven made from 100% polyester is the very cleanest available, but is only sorptive to organic solvents.
Mops with polyurethane foam heads tend to deteriorate and crumble during use, which is clearly a problem. One manufacturer has obviated this by laminating a knitted polyester fabric to slabs of polyurethane foam, which can then be fitted to a special mop handle. The sorptiveness and squeezability of the foam is preserved, while the polyester acts as a barrier against physical disintegration of the polyurethane.
The cleanest documentation paper in existence is made from spun-bonded polyethylene, commonly sold as Tyvek. Its only drawback is that, while easily written on, printed, etc, it does not pass cleanly through all kinds of photocopying equipment.
It used to be that cleanliness and sorptiveness in wiping materials were inversely related to one another. Clean items tended to be terrible sorbers of fluids, good sorbers tended to be filthy. In recent years this has changed, and functionality has been uncoupled from cleanliness. Several wipers are now available which are quite clean, yet are also capable of picking up spills of liquid rather than merely moving the fluid around on the surface.
Ignoring cleanliness, the best way to gauge the economics of wiper selection lies with calculating the cost for a wiper to sorb a given volume of liquid. The numerator for such a measure - the cost of the wiper per unit area - is obtainable from suppliers. The denominator - the sorptive capacity of the wiper per unit area - can be obtained by direct experiment using for example, IES Recommended Practice RP-004.2.
The discussions on garments covered several areas which can create an emotive response from users. These included head covering, which users found too hot or generally uncomfortable, and which are problems that need to be addressed by manufacturers to establish the underlying problems.
Another problem area was masks, should they be reusable or disposable, and how best attached, and of what design.
Another area of discussion was on whether upgrading garments from laboratory coats to coveralls would reduce contamination in the cleanroom. It was thought that it would. It was also suggested that more people should refer to the International Standards recommending which garment style should be worn in specific clean areas.
Advice was also sought on undergarment selection. Again this is very dependent on individual circumstances, but it was broadly agreed that being able to control and specify garments worn directly under a Cleanroom garment was desirable, especially in pharmaceutical manufacturing areas.
All groups showed the same areas of concern. These were:
Discussions on how to train new staff indicated this is a particular problem area. A number of key issues were identified that needed to be part of any training schedule. These included why cleanrooms are used and how they were developed, terminology and basic operation, nature of contamination and its control, monitoring and testing of staff and premises. Selection of staff was also raised as an issue, and especially dealing with unsuitable staff.
Retraining of existing staff poses different problems. Existing staff think they already know the subject, and attempting to 'retrain' suggests a lack of competence. Continuing Professional Development, Advances in Cleanroom Technology and similar terms can be used to soften the impact, but it was agreed that continued training was essential. Several delegates admitted that it was only during the re-training that gaps in knowledge became apparent.
One of the problem areas identified with monitoring adherence to correct protocols was the attitude of senior management. Cleaning staff were also thought to be a problem. It was agreed that a properly structured training programme made the assurance of correct protocol usage higher. It was suggested that proper monitoring, possibly including CCTV surveillance, was useful, but the problem of dealing with non-compliance remained. Using CCTV allowed recordings to be made, and faults taken up with the individual. It was also suggested that such videos could be used in training programmes.
Although garments were covered in another workshop, the subject was also raised as part of training. A table distilled from International cleanroom standards was shown, giving guidance on selection and correct donning and removal procedures. It was thought that this was an area where staff incompatibility was shown, and also that it was an area where any mistakes quickly lead to an increase in contamination levels.
As introduction for the discussions, a brief definition of monitoring was given as follows:-
Process monitoring comprises all measurement and documentation activities related to a manufacturing process. The objective is to obtain a comprehensive set of data in order to prove that the process has performed uninterruptedly within its specified limits. Cleanroom technology related parameters are fully integrated into the process monitoring scheme.
It was added that the Workshop would focus on the contamination control parameters of process monitoring, and that it was up to the participants to identify the problem areas they wished to discuss.
The Workshop participants originated mainly from the pharmaceutical industry. The remainder, from industries such as medical devices and blood products, were also interested in the biocontamination aspects of monitoring. Only 7 participants from a total of over 100 were identified as from the micro-electronics industry.
Consequently, the topics discussed focused on biocontamination control issues. Typical items were:
Once again thanks to the people who made the event such a success:
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Editor's Comment: Many fascinating and important issues are raised.I hope to revisit several
of these sites.If you have contributions to make in any of these areas
then PLEASE get in touch. |