Clean Rooms Done Right
Processors requiring a Clean Room Environment take different approaches.
Of course, the production area is equipped for negative airflow and production employees pass through a dressing room where they don caps, clean suits and booties to avoid any contamination of the clean room environment. Ideally, their only purpose to be in the production area is to produce product and not maintain equipment.
Some processors carry the negative airflow a step further – to their whole facility, including where auxiliary equipment is located and even to office and hallway areas.
In the production area, processors usually want to minimize the amount of equipment required to only what is required to produce product. Auxiliary equipment, material and vacuum lines are placed outside that production area thus minimizing maintenance personnel and maintenance tasks that are required in the production area. This approach has been time tested as the best way to really ensure a clean environment.
It’s important to work with primary and auxiliary equipment manufacturers who recognize your needs and have experience with clean room installations. That means knowing how to design a system that helps you keep the clean room CLEAN. Some auxiliary equipment manufacturers tout “clean room auxiliaries” at a premium price because they have extra seals and enclosures. It would still be unwise to add this equipment to the processing area where most processors want to minimize equipment to the bare essentials. Likewise, why spend extra money on “souped-up” equipment if it is going outside the processing room.
Knowledge and experience in designing conveying/drying systems for clean room applications is essential.
Vacuum conveying is a necessity because a vacuum system keeps dust enclosed within the system rather that blowing it into the surrounding air. Even then, vacuum and material conveying lines should be kept out of the production area as much as possible. That may mean running lines underground so lines come up through the floor next to presses. (photo2 and 2A) Another choice is to place lines and auxiliary equipment in a room next to the production area and run material lines through a walls that are close to the processing machines. (photo3)
Central Drying/Conveying is typical with large clean room operations. All this equipment can be placed compactly in a separate room where cleaning and maintenance be accomplished as needed without the possibility of contaminating the clean room.
In cases where this design objective can be met, the material storage, drying, blending, selection and conveying equipment is outside the production area. Cleaning and maintenance of auxiliary equipment can be accomplished as needed without the possibility of contaminating the clean room.
Material distribution is controlled from the same area and typically, some kind of Auto ID is included to preclude having a material go to the wrong machine.
When placing equipment inside of the cleanroom when necessary, there are certain imperatives that are universal:
- Use of materials that comply with cleanroom production requirements such as stainless steel / non-corrosive contact surfaces, HEPA filtration media, sealed vessels that eliminate dust contamination in the clean environment…etc. While some auxiliary equipment companies produce specific custom equipment lines to meet these requirements, they tend to be more expensive and less readily available. A better decision is to work with a company whose standard equipment will be applicable in a cleanroom environment with the above requirements already in mind. Standard equipment is more cost effective and can be supplied with normal lead times.
- Use of filterless resin receivers, when applicable, that allow dust and contaminates to be conveyed out of the cleanroom environment and in to filtration units out in the utility area, not in the cleanroom environment. Filterless Receivers in combination with Cyclone and Filter Dust Collectors located outside of the cleanroom environment, eliminates dust contamination that would occur when cleaning or replacing filters.
- Clean Room drying equipment that requires little or no maintenance and is sealed keeping any contaminates from entering the cleanroom environment. If dryers must be inside the clean room, there are non-desiccant membrane dryers for this process. These dryers eliminate dust contamination and with just one maintenance check required each year this is virtually no risk of cleanroom environment contamination.
- Routing of resin conveying lines, water and air piping, electrical power connections and other utilities inside of ceilings, walls or under the floor such that they these conduits are not surfaces for dust, dirt and contaminants to settle on and fall into the production environment.
These are some examples of cleanroom approaches when applying auxiliary resin handling, blending and drying equipment in cleanroom environments. The keys to successful design and construction of cleanrooms, from a molding resin handling equipment and systems perspective, are containment of the equipment outside of the cleanroom environment, design of standard equipment to function inside of these environments, when necessary, by making them as maintenance free as possible.