After a clean room is validated and becomes active it must regularly be checked in order to ensure that it continues to meet initial standards. Specific standards list the time intervals at which clean rooms should be tested and the minimum requirements a clean room must meet. These standards include ISO 14644-2. The testing outlined in the standard ensures that the product manufactured in the room will be fit for its intended purpose.
Clean Room Classes
*There are two major types of clean rooms. These two types are distinguished by their ventilation systems and can be either turbulently ventilated or unidirectional flow.
-Turbulently Ventilated
Also known as nonunidirectional. This type of ventilation system supplies clean, filtered air through a terminal high efficiency filter. It also employs air diffusers located in the ceiling. The clean, filtered air mixes with the room air and removes airborne contamination and particles using air extracts located on the bottom of the walls.
The air changes are usually equal to, or greater than 20 per hour. This is a much higher rate of air changes than those found in ordinary rooms, like offices. In a turbulently ventilated room, airborne contamination generated by use of the room is mixed and diluted with filtered air and gradually removed.
-Unidirectional Flow
These clean rooms have incorrectly been known as 'laminar flow' clean rooms in the past. Unidirectional flow clean rooms require a much greater quantity of air than the turbulently ventilated type. They also provide much more consistent cleanliness.
Guideline Principles of Clean Room Validation/ Testing
*Certain principles are used to guide the validation and maintenance of clean rooms:
-Air movement in the clean room should be sufficient to ensure that no areas within the room collect high concentrations of contamination.
-Air supply to the clean room is high quality and will not add significantly to the contamination in the room.
-Air supplied to the clean room is of sufficient quantity to dilute or remove contamination generated in the room.
-Air in the clean room moves from clean to less-clean areas. This minimizes the undesirable movement of contaminated air. This movement is particularly important in relation to doorways and construction fabrics.
Clean Room Tests/ Clean Room Validation
*To ensure that the above principles are upheld there are certain tests that should regularly be performed to determine the effectiveness of the clean room. These tests include:
-Air Supply and Extract Quantities
For turbulently ventilated rooms, the air supply volumes should be measured. Extract volumes should also be measures periodically. For unidirectional airflow rooms the air velocity should be measured.
-Pressure Differential Between Areas
It is important to confirm that all airflow in the clean room occurs in the desired direction (from more clean to less clean). Measuring pressure difference between two designated areas allows airflow direction to be determined.
-Filter Installation Leak Test
The High Efficiency Particulate Air (HEPA) filter and it's housing must be checked periodically to ensure no airborne contamination can by-pass the filter installation and enter the clean room.
-Containment Leak Testing
Testing is necessary to confirm that no airborne contamination enters the clean room from adjacent higher pressure areas through leaks in the construction testing.
-Air Movement Control and Recovery
The type of air movement control test needed is determined by the ventilation system in the room. Turbulently ventilated rooms need to be checked to ensure that there are no areas within the room with insufficient airflow. Unidirectional airflow rooms should be checked to ensure the air velocity and direction is correct, particularly within the critical area where products are exposed to contamination.
It may also be necessary to test the 'recovery' of conventionally ventilated clean rooms from test particles or from naturally occurring particles that are introduced to the room.
-Airborne Particle and Microbial Concentrations
Once these tests have been passed the room will be measured for airborne particle concentration levels and, if applicable, microbiological to ensure that these levels comply with design standards.
Optional Tests Used in Clean Room Validation
*As well as the contamination control tests listed above, it may also be necessary to satisfy one or more of the following requirements:
-Sound levels
-Lighting Levels
-Temperature
-Humidity
-Vibration Levels
-Heating and Cooling capabilities of the room
*These tests may be used for information purposes.
This section provides a general overview of the importance of clean room validation in the pharmaceutical and biotech industry and gives detailed information about the validation process.
4 comments:
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