Below are some frequently asked questions relating to Clean Environments
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Many everyday items have cleanroom variants. These are made from non-shedding materials meaning that they are safe to use in the cleanroom.
Products and materials that are subject to shedding or particulate generating should be banned from the controlled area e.g. cardboard, wood, and mild steel products that might be subject to corrosion.
There is also the matter of material and chemical compatibility issues with your process, particularly if the cleanroom space and equipment are subject to frequent wipe downs or sterilization processes.
There may well be process specific materials that are also banned. Best practice would be to check all materials with a supervisor when entering a controlled area.
Equipment may be required that is specific to your process for example ESD and grounding equipment for sensitive electronic/microelectronic devices.
Depending on your process you may have a particle counter in the cleanroom which may have an alarm to indicate if the particulate level is increasing.
In terms of furniture and equipment, the general rule should be ‘as little as possible’. If it is not crucial to your process, don’t have it in there. All surfaces provide a space for particulate to build up.
You will have an operating procedure for the wipe down of the cleanroom and this will be specific to your process but in most cleanrooms you need to do a full wipe down at least once a week.
A full wipe down would involve cleaning each individual item, around the item, and under the item. That includes large items like desks, chairs, and shelving units, and small items such as beakers, containers, everything in the container etc. The more you have in there, the greater the task.
In order to control the particulate levels in your cleanroom, operators must wear appropriate cleanroom garments and follow strict cleanroom protocols whenever working in or around a cleanroom.
The protocol will vary depending on the classification of your environment and your process.
As a general guide;
The filter condition gauge or minihelic gauge is measuring the differential pressure between ambient and the HEPA filter. This pressure reading will increase over time as the filter blocks.
The Clean Environments team will specify your ‘safe range’ on the filter condition gauge; enabling you to accurately assess and maintain your air quality by replacing the HEPA filter precisely when required.
Laminar Air Flow. ISO 5 (Class 100) and cleaner facilities rely on unidirectional, or laminar, airflow. Laminar airflow means that filtered air is uniformly supplied in one direction (at a fixed velocity) in parallel streams, usually vertically.
Turbulent Air Flow.Cleanrooms up to ISO 6 (Class 1,000) do not require laminar airflow and may utilize a non-unidirectional, or turbulent, airflow. This means the air is not regulated for direction and speed.
The advantage of laminar over turbulent airflow is that it provides a uniform environment and prevents air pockets where contaminants might congregate
There are many different ways of describing an ISO 14644-1 class 5 cleanroom. These can include; ISO 5 cleanroom, grade 5 cleanroom, ISO 5, class 5.
ISO 14644-1 class 5 is equivalent to the old US federal standard 209 class 100.
To compare this to the EU GMP standard, Grade A is approximately ISO class 4.5.View classifications
Maintaining the correct pressure levels is fundamental to the function of the cleanroom. If the pressure is too low contaminants can enter. A magnahelic pressure gauge can measure the differential pressure between the clean (white) zone, gowning room and ambient.
We would advise that you maintain around 30 pascal of positive pressure inside your cleanroom and 15 pascal in your gowning room. Maintaining this level of pressure will guarantee that no air born contamination will enter your cleanroom.
This depends on what you are trying to protect. Positive pressure cleanrooms protect the process inside the room from any particulate outside the room. Negative pressure cleanrooms protect the user from the process.
Clean Environments have a range of rapid assembly positive pressure cleanrooms. In order to maintain positive pressure, you must make sure that you are controlling not only the amount of air that enters but crucially the amount of air that exitsthe room. If you have no control on how the air is exiting. You cannot balance the room and maintain a good level of positive pressure.
A micron is the unit we use to measure particulate. One micron is equal to one-thousandth of a millimetre. The smallest particle the human eye can see is 30 microns
This will depend on what ISO level you are trying to maintain.
In order to achieve these levels you can use a simple fan filter unit which comprises of a pre filter (G filter) and a final filter (EPA, HEPA or ULPA). Or, if you are also controlling temperature and humidity, you would use a HVAC system in which you would have a pre-filter (G filter), a fine-filter (M or an F filter) and a final filter (EPA, HEPA or ULPA).
A pre-filter captures coarse dust. A fine-filter captures particles measuring 0.2- 3 micron and a final filter removes air born particulate; that is those particles measuring 0.1 -0.3 micron.
The classification of the filters are calculated according to how efficient the filter media is at removing the stated particle size.
There are quite a few options in each category but here at Clean Environments we use a G4 pre filter and a H14 final filter as standard.
A cleanroom is an enclosure that controls the amount of particulate (dust and other contaminants) in the space.
It does this by controlling a number of factors;
The build materials and surfaces in the room need to be designed for easy cleaning and to limit the areas that particulate can build up.
Controlling the air entering the space via a filtration system. The final filter will be some sort of HEPA filter. The cleaner the space the more often you will want the air to pass through this filtration system (increasing the number of air changes per hour)