Displaying items by tag: airflow
Cleanrooms are facilities designed for conducting research or manufacturing products that require extremely clean environments. Typically, cleanrooms employ a broad range of techniques to prevent air particles, bacteria, and other contaminants from entering the workspace, often using an employee dress code and washing, pass-thru lockers and chambers, and intensive detail to cleaning. However, one of the major forces keeping a cleanroom particle free is the air filter system. Cleanrooms employ many different types of filters, including HEPA filters and ULPA filters, but there are two standard air flow patterns that are consistently used: laminar flow and turbulent flow.
Air is of fundamental importance to cleanrooms, either as a contamination source (microorganisms carried in the air-stream) or as a control measure to minimize contamination (through the supply of clean air and controlling the direction of air movement). Therefore, controlling a cleanroom requires careful attention to the factors of air filtration, air velocity and air flow. While cleanrooms are typically designed to achieve turbulent airflow, with clean air devices, and EU / WHO GMP Grade A / ISO 14644 class 5 areas, the air is designed to be unidirectional whereby the air direction and air velocity are designed to remove any contamination deposited into the air-stream away from the critical area. These devices contain HEPA filters, which control the air-speed and direction.
Clean rooms are “created” when clean room designers like Vernick & Associates bring together engineering design, fabrication, finish, and operational controls to convert a “normal” room to a “clean room” so that they can be used for manufacturing. These clean rooms must meet the requirements defined in the Sterile Code of Annex 1 of both the EU and PIC/S Guides to GMP and other standards and guidance as required by local health authorities.
Cleanrooms are used in practically every industry where small particles can adversely affect the manufacturing process. They vary in size and complexity, and are used extensively in industries such as semiconductor manufacturing, pharmaceuticals, biotech, medical device and life sciences, as well as critical process manufacturing common in aerospace, optics, military and Department of Energy.
Problem: Maintaining air quality is essential to meeting criteria for cleanroom standards, and air quality cannot be measured without also measuring the air flow within the cleanroom environment. Specialized tools are required to gather the readings that represent the air flow through the ventilation systems, as well as a solid understanding of those systems.
Solution: There are several types of ventilation system setups commonly used in cleanrooms — each of which are put in place to remove contaminants from the environment and help meet and maintain cleanroom standards. It is necessary to check the air flow of those ventilation systems periodically, as many factors can affect the movement of air over time, such as buildups in the ducts, leaks, aging and worn fans and pumps, etc. Here we identify the most common types of ventilation systems used in cleanrooms and the most appropriate instrumentation to monitor the airflow throughout those systems.
Clients often come to me specifically requesting an “ISO 7 cleanroom” or an “ISO 8 cleanroom.” What they often fail to realize is that the ISO class does not define the layout of the cleanroom. It only defines the cleanliness level that needs to be met. In fact, the ISO classification actually corresponds to a specification of how clean the cleanroom must be. The ISO 14464-1 standard doesn’t say how to design the cleanroom, it only specifies the maximum quantity of air particles allowed.
The building housing this expansion was comprised of offices, labs, manufacturing and support spaces, with a total of over 220,000 square feet of space. Distinctive air-handling zones existed for the offices, the labs and the manufacturing areas. Offices were served by several packaged single-zone systems. The labs and the manufacturing areas used air handlers utilizing chilled water and hot water coils.
Clean rooms need a lot of air and usually at a controlled temperature and humidity. This means that in most facilities the cleanrooms Air Handling Units (AHU) consume over 60% of all the site power. As a general rule of thumb, the cleaner the cleanroom needs to be, the more air it will need to use. To reduce the expense of modifying the ambient temperature or humidity, AHU or systems are designed to recirculate (if product characteristics permit) about 80% air through the room, removing particulate contamination as is it generated and whilst keeping the temperature and humidity stable.
Cleanrooms are defined as a room or suite of rooms, in which the concentration of airborne particles is maintained within established parameters and where other factors are controlled to within specified limits. The most effective way of maintaining the air quality in a cleanroom is to operate and maintain it correctly.
Everything in the cleanroom, including the lighting fixtures, is designed to ensure successful air filtration and maintain the laminar airflow in a contamination-free environment. Depending on the function of the controlled environment, a cleanroom will use either HEPA or ULPA filtration. These air-filtering systems are typically an expensive component and one of the first to be considered in construction. They take up a majority of the ceiling space, which leaves a real challenge for lighting the environment.