Tuesday, June 28, 2011

Modular Softwall Cleanrooms

Simple, Mobile, and Cost Effective
Softwall modular cleanrooms are designed for functionality and reduced cost while providing all the flexible benefits of modular construction. They are tent-like, lightweight, easy-to-assemble structures, which can be installed free standing or suspended from the ceiling of an existing building. Unlike their fixed-wall counterparts, softwall cleanrooms are generally smaller, portable, and can fit into tight spaces. The portable design enables the cleanroom units to be easily moved to another location or disassembled and stored. Because of their relative low cost, softwall cleanrooms are ideal for small or startup businesses, or manufacturers looking for a quick, easy way to expand their cleanroom operations.
The cleanrooms are available in a variety of sizes and classifications, with options to match a customer’s specific needs. From standard 4 feet by 4 feet units, to sizes as large as 24 feet by 36 feet. Larger, custom sizes can be designed and built to meet customer requirements. Because of their modular design, rooms can be expanded or reduced in size without taking the entire cleanroom down, making it easy to add or remove sections. Softwall rooms are also available in a variety of cleanroom classifications, but most commonly in Class 100,000 to Class 10 (ISO 8 to ISO 4) designs.
A wide variety of industries use softwall cleanrooms, from medical device manufacturers to makers of rolled films. This design is also popular in microelectronics and semiconductor manufacturing, as well as electronics repair industries where contaminants cannot be allowed into sensitive areas of electronic devices.
The basic building block of the softwall cleanroom’s modular design is a sectioned ceiling framework made up of tubular steel beams with T-bar cross members. This interlocking ceiling grid system enables easy assembly and cleanroom expansion. The ceiling is supported by tubular steel legs at each of the four corners and reinforced with heavy gauge, triangular steel gussets. Powered HEPA filter units, lighting systems, and ceiling panels are sealed to the grid using gaskets, providing a zero-leak cleanroom.
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Interior height of the ceiling framework is commonly 8, 9, or 10 feet, although various heights are available depending on the customer application. Standard filter unit height is 14 inches, with a two-inch minimum space required between the filter unit and facility ceiling. The common structure height enables the modular softwall cleanroom to easily fit within an existing building.
Softwall cleanrooms, without a center support, have a maximum size of 12 feet by 12 feet with a leg on each corner. Larger rooms can be constructed, but additional support posts within the structure are required. For example, a room 16 feet by 20 feet would have one center post or a room 20 feet by 32 feet would have three center posts. Other options are available for clear spans without center legs. For example, ceiling-suspended softwall cleanrooms eliminate the need for all support legs and columns. This configuration allows the cleanroom to easily accommodate equipment layout and maximizes floor space utilization.
The walls of most standard softwall modular cleanrooms are made of 20 or 40 mil clear vinyl and are fire retardant with an anti-static additive. Cleanroom-grade softwalls with low outgassing and static-dissipative vinyl are an available option. Entering or exiting most softwall cleanrooms is by way of vinyl strip doorways. The strip door commonly consists of eight-inch-wide, 80 mil thick strips with a two-inch overlap on each side along the length. Entering a cleanroom requires only to push apart the strips, which automatically reseal as they come back together. The strip doors are pre-assembled and are easily mounted to the ceiling structure. Swinging doors in metal frames are an available option when acrylic or Lexan walls are used.
The controlled level of contamination will vary depending on quantity and configuration of filters. For example, the ceiling structure of a Class 10,000 (ISO 7) cleanroom will have a combination of powered HEPA filters, lights, and blank panels. In contrast, Class 10 (ISO 4) cleanrooms require 100% ceiling coverage with powered filters in all ceiling grid sections.
When ceiling space for lighting is limited due to filter requirements, flow-thru lights can be used. These are similar to standard cleanroom lights with the exception that a motorized ceiling HEPA filter unit is mounted directly on top of the light. This fixture is designed with open areas so filtered air is able to flow through the light fixture down into the cleanroom. Flow-thru lights are also valuable in situations where concentrated “clean areas” and lighting need to be achieved within a cleanroom. The filter unit and light fixture are pre-assembled together to form one complete flow-thru light unit.
Filtered air is exhausted from the cleanroom beneath the flexible vinyl walls. An adequate gap of about six-inches between walls and floor is necessary for air to flow through the room and escape. Air volume is typically about 200 feet per minute, and at that rate the flexible walls tend to bow outward a little because of positive air pressure created by the powered filters. A small amount of wall flex is nor mal, but if the wall-to-floor gap is too small, the air will push the panels outward to an unacceptable distance and inhibit good laminar airflow. If the gap is too large, the cleanroom will not keep enough positive pressure to push contaminants out.
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Like their hardwall counterparts, softwall cleanrooms have a large number of options available depending on customer needs. Anterooms or gowning rooms can easily be added to the cleanroom. They, too, are portable and can be relocated along the outside perimeter of the cleanroom for adaptation or modifications to manufacturing processes.
If needed, softwall cleanrooms can be mobile. When equipped with optional braked casters, they can easily be moved to a different location within a facility or stored. Casters are used for smaller cleanrooms, and customers who wish to install casters on rooms larger than 12 feet by 12 feet should seek advice from their supplier.
Optional acrylic or Lexan panels provide a flexible, yet sturdy and attractive wall alternative. Product passthroughs can also be included in the design. Additional options include: special room heights, solid doors, yellow or opaque sidewalls for ultraviolet light filtration and security, stainless steel frames, building suspension brackets, and ionization equipment.
Modular softwall cleanrooms are pre-fabricated at the factory for quick installation. Customers can easily install standard rooms onsite within one-to-two days. All electrical connections are simplified using a continuous series of plug-together, pre-fabricated wiring system. Starting at the room’s electrical junction box, power cable segments are connected to each ceiling light and powered filter unit. This allows the user to connect any number of lights or filter units within their circuit.
Softwall cleanroom maintenance is simple, but requires regular cleaning to ensure optimum performance. Powered filter units use a prefilter and these must be visually checked on a regular basis. If the filters are dirty, they must be changed. The HEPA filters are somewhat maintenance free, but it is recommended they be re-certified by a third party every year. All interior surfaces and floors must be cleaned on a regular basis.
A modular softwall cleanroom is a low-cost investment, which provides a highly functional cleanroom solution for manufacturers. The flexible structure creates a controlled environment that is able to meet the needs and requirements of small- to large-sized companies. Softwall cleanrooms are designed with the customer in mind, covering a wide range of industries and diverse applications.

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