Doors play an integral role
High-performance doors and flexible industrial fabric walls have evolved in recent years and are a viable option for various food and pharmaceutical applications.
The primary function of most industrial doors is to provide tight environmental separation, yet allow occupants and equipment to quickly and safely move from one area to another. In pharmaceutical manufacturing, doors assume an even larger role by allowing companies to achieve and maintain a specified level of cleanliness for a given cleanroom. High-speed fabric roll-up doors (also called upward-acting doors) are commonly used in cleanrooms. They are also an integral part of airlocks that form buffers between different classes of clean areas.
Cleanrooms are generally classified according to the number of particulates in the air. The cleanest allow for the fewest particulates. The goal in virtually all cleanrooms is to maintain an air pressure differential between rooms, pushing air from the opening’s cleaner side to the less-clean side. Occasionally, the goal is to keep particulates within a certain room to avoid cross-contamination with the processes in adjoining rooms. For these reasons, most facilities incorporate multiple pressure steps within the building’s structure. The steps typically range from 5 to 13 Pa (0.02 to 0.05 w.g.) between rooms, but can be as high as 50 Pa (0.2 w.g.).
A door capable of at least 50 Pa in pressure differential is needed to maintain a tight seal and minimize air leakage. Given the requirement to maintain pressure differentials, doors that seal tightly and cycle quickly are essential in pharmaceutical manufacturing. A properly designed door helps ensure the facility’s makeup fans can satisfy the required amount of makeup air needed to maintain pressure. Another prerequisite in overall door design is cleanliness, since doors must operate in a pristine manufacturing environment. Any high-speed door used in pharmaceutical manufacturing must also balance the need for productivity with operational safety.
Specifying high-speed roll-up doors
Bi-parting doors made from stainless steel or fibreglass are widely used in pharmaceutical manufacturing facilities. Many companies will use fabric roll-up doors to meet the needs of specific applications where bi-parting doors will not fit due to limited wall space in a plant.
A roll-up door uses little wall space because it is an upward-acting unit, where the ‘curtain’ of the fabric door collects in a head assembly at the top of the door when it is opened. By comparison, a rigid-panel door that opens from the centre requires considerable wall space on each side of the door in order to function. As an example, a door spanning a 1.8-m (6-ft) wide opening requires approximately 0.9 m (3 ft) of wall space on each side of the opening so each panel has a place to travel when opened.
A new generation of roll-up doors has come on the market in recent years featuring anti-microbial materials and other upgrades for cleanroom applications. These new features, coupled with their ability to operate at high cycle speeds and provide tight sealing capability, are reasons they are catching on with pharmaceutical and food manufacturers.
Choosing a cleanroom door
Commonly referenced in Canada, the U.S. Food and Drug Administration (FDA) cleanroom standards outline recommendations and requirements for manufacturers of pharmaceuticals and medical devices. The starting point is to look for doors compliant with Current Good Manufacturing Practices (CGMPs), the U.S. Food and Drug Administration (FDA), and United States Department of Agriculture (USDA).
Key considerations for any door configuration are ease of cleaning and durability. In all cases, these doors must be able to stand up to repeated cleaning with chemical solvents and have a smooth, hard, nonporous surface resistant to microbial and fungal growth. Doors should also have a tapered surface and edges that essentially eliminate the harbouring of dust or other contaminants, and possess no sharp angles to minimize harbourage of microbes. Additionally, they should:
- be corrosion-resistant (which is often a problem with older door systems);
- use stainless steel side frames and shrouds; and
- incorporate a lubrication-free design, since lubricants can attract particulates.
It is also advisable to avoid doors with exposed fasteners and coils, as they will take longer to clean and could harbour various contaminants.
The ability of cleanroom doors to accommodate site-specific needs is another consideration for industrial designers. These could include features such as vision panels, push plates, or other activation devices, as well as magnetic locks and (perhaps most importantly) interlocking systems. Commonly known as airlocks, these systems are found in entrances and exits, gowning and de-gowning areas, and material transfer locations. In all these areas, it is important to keep two doors from being open simultaneously, thus preventing air infiltration from one space to the other.
The best door systems allow for wireless interlocking of air locks. Breakaway capability is another recent advancement in cleanroom doors, allowing employees to push through the curtain in the event of a power failure. While this feature is not needed on a frequent basis, it will be greatly appreciated on the rare occasion it is required. Finally, low-voltage remote controls should be specified if possible as they provide a cleaner look and are easier to install.