These Environmental Control Modules address a central cleanroom dilemma: high-technology equipment requires smaller geometries (and more stringent environmental standards), while the necessary cleanrooms become increasingly expensive to construct and maintain.
In fact, research suggests that particles in the sub 0.1 micron range, which can degrade today’s most sensitive components, are largely unaffected by cleanroom laminar flow airstreams. The disturbing consequence of these findings is that many submicron particles—once they are introduced into a cleanroom—may be nearly impossible to remove, even with sophisticated HEPA filtering systems. At the heart of this problem are humans themselves— by far the greatest source of contamination in a cleanroom.
Isolated controlled-air environments provide a cost-effective solution to this problem. Once an operator is removed from the processing or storage area, maintaining superclean conditions becomes much easier—and much more affordable!
Terra’s Environmental Control Modules provide a versatile, economical approach to this mini-environment concept.
Their design flexibility allows you to construct a laminar flow or exhaust purification/removal system for virtually any sized enclosure. Hoods are available for use with two, three, or four filter/blower modules, and several hoods of any size can be positioned together to form as large a work station as you need. Blower/filter modules attach securely to hoods by means of a few screws, and gaskets ensure an air-tight seal.
Further, blower/filter modules can be wall mounted to provide continuous filtering/recirculating, or operated as free-standing systems to deliver a continuous supply of Class 10 air (or purified exhaust) to a remote benchtop or enclosure.
The low-profile filter/blower module incorporates 1200 CFM impeller blowers designed for quiet, continuous duty. A flexible mounting system enables it to function as a positive-pressure blower in one set of applications, drawing air through intake baffles and directing filtered air through an exhaust grid. In the other mounting position, it functions as a negative-pressure ventilator, drawing exhaust fumes through a charcoal purification filter and then releasing them through 8"-diameter exhaust flanges.
The polypropylene housing accommodates a variety of filters. HEPA (High- Efficiency Particulate Air) and ULPA (Ultra-Low Penetration Air) filters provide Class 10 (and cleaner) air flows—refer to performance graph for flow rate and particle counts. Exhaust purification filters remove from the air stream the fumes produced during soldering, screen printing, chemical titrations, and other processing operations (see page 392 for characteristics of exhaust purification filters). Filters can also be used together in the same housing to ensure a clean, purified exhaust flow.
Hoods are designed to fit on a standard table when interfaced with the filter/blower module. Hoods for vertical flow applications are designed for tables 30" deep or deeper. Hoods for horizontal flow applications require a 34"- 44" deep table to accommodate both the hood and filter/blower. Both hood designs are available in three widths. All hoods feature a segmented access shield that allows ample operator access to the working area and also closes completely to minimize contaminants. Stainless steel hood frames support your choice of five different hood materials.
This range of sizes gives you complete flexibility to design a system that meets your requirements.
Double-width hoods provide ample working space for one operator. Larger hoods maintain effective laminar/exhaust flow rates for larger working areas and several operators.
In fact, their economical, modular design lets you configure a bank of controlled-air enclosures as wide as you want. Because each incorporates its own filter/blower module, the system maintains a uniform laminar flow across the entire work area—no matter how large it is—with minimal noise and turbulence. Compare this working environment with the noisy, wind-blown processing areas in systems that rely on a single, centralized filter/blower!
Hoods are available in five materials. Terra’s light-weight, transparent staticdissipative PVC, which features a surface resistivity between 106 and 108 ohms/square, safely eliminates static build-ups and the particles they attract, making surfaces clean inside and out. Nondissipative PVC and polypropylene enclosures are ideal for use with a wide range of caustic fumes. All hoods feature a stainless steel reinforcement frame for optimal strength and stability.
Hoods can also be equipped with a conduit flange to allow remote applications. Simply specify desired location of input/exhaust when ordering.
Laboratory hoods serve a number of critical purposes in the lab environment.
Such hoods, often called laminar flow workstations or clean benches, use a flow of HEPA-filtered air to prevent influx of viable and non-viable particles into the enclosure and to sweep away any contaminants generated by the work process.
For fume containment, laboratory fume hoods use a ducted ventilation system that maintains negative pressure. Where ducting is impractical, ductless hoods are also available for removal of non-hazardous contaminants (fumes or particles), using either HEPA or activated carbon filters.
Biological safety cabinets combine aspects of both hood types: a laminar flow of micro-filtered air and negative-pressure containment of bio-hazard fumes.
Laminar flow hoods (also called laminar flow clean benches) force air through a HEPA or ULPA filter to create a clean work area free of nearly all contaminating particulates, including bacteria, mold spores and many viruses. These hoods use a vertical or horizontal airflow design. Both provide excellent protection of products from particulates and cross-contamination, but do not protect the operator or environment.
So why choose one over the other? Vertical laminar flow hoods (VLF Hoods) require less floor space, but more overhead clearance. In addition, a sash at the front of the VLF hood provides a barrier between air exiting the hood and the operator’s face. VLF hoods create turbulent air flow when air strikes the work surface, requiring sterile work to be performed above the work surface.
HLF hoods minimize air turbulence (and particle backflow) on the work surface except where equipment disrupts the horizontal airflow. However, they direct the airflow directly at the operator’s face and require more depth to accommodate placement of the fan filter unit at the rear of the hood.
Laboratory fume hoods draw air from the environment through the opening of the hood, allowing environmental contaminants into the work area. Thus, lab fume hoods do not offer a sterile environment or product protection. Instead, chemical fume hoods are designed to protect the operator from dangerous or irritating fumes and powders generated from work performed inside the hood.
In ducted fume hoods and canopy fume hoods, air passes out of the hood through a duct leading to an in-house ventilation system that contains and/or neutralizes hazardous materials.
In ductless fume hoods, fans draw exhaust air through a series of filters that remove irritating substances before release back into the room. Since these filters are not 100% efficient in removing all substances, ductless fume hoods are not advised in the presence of biohazards; however, they provide a convenient, cost-effective solution for operations involving irritating but non-hazardous fumes in facilities where an in-house HVAC system cannot be accessed.
Biological Safety cabinets combine design aspects of both laminar flow and fume hoods. Filtered air is directed downward onto the work surface and then travels into a plenum through openings on the front and sides of the hood. Depending on the classification of the biosafety hood, some percentage of air is recirculated through a HEPA filter while the rest is directed out of the hood through an exhaust system. Thus, biosafety cabinets offer operator, environmental and product protection.
These laboratory safety cabinets (sometimes called IV hoods or compounding hoods) are ideal when preparing sterile medications such as chemotherapeutic agents that may pose a risk to the operator.
When it comes to working with hazardous or potentially infectious material, protecting personnel must be the primary concern. However, offering personnel protection does not have to come at the cost of risking product integrity. Class II BSCs provide protection to both personnel and product simultaneously. They maintain an ISO class 5 clean work area for product manipulation, while ensuring that exhaust air is filtered and ducted out of the environment. Thus, a class II BSC is the ideal solution when working with moderately hazardous material and both personnel and product safety are required.