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A New Era in Filtered Fume Enclosure Safety
Many common laboratory procedures result in the generation of hazard- ous fumes. When operated properly, filtered fume enclosures can control gases, fumes, and powders, and can prevent inhalation of highly toxic substances, including carcinogens. In the past, it was often acceptable to conduct scientific experiments with volatile chemicals and toxins on an open bench without containment. Regulations now state, however, that such experiments must be conducted within an environment that will ensure efficient and safe fume containment.
The latest ductless filtered fume enclosures address these needs di- rectly, and are a vital resource in the safe and effective operation of modern industrial, educational, hospital, forensic, and pharmaceutical scientific laboratories.
Air velocity
For hazardous fume containment, there must be sufficient and uniform air velocity, or face velocity, across the sash of the enclosure. If this veloc- ity is too low, it may not be sufficient to overcome competing airflow caused by the movement or position of the operator in front of the en- closure. If the face velocity is too high, it can lead to a “roll effect,” which occurs when entering air causes a vortex, sending air across the work surface, up the back, and along the top of the enclosure. This air then becomes trapped, potentially leading to a dangerous escalation of con- taminant levels. In some instances, the contaminated air can “roll out” of the enclosure into the operator’s breathing zone, endangering the operator and other laboratory occupants. Not only does the roll effect have serious safety consequences, it can also disturb delicate operations and experimental results, potentially jeopardizing years of research.
Digital control technology
A variable air volume system within a laboratory must have a fast and responsive control system to provide effective fume containment. The majority of existing filtered fume enclosure systems use analog control technology. These systems do not have the flexibility to respond to dynamic changes in fume enclosure and laboratory conditions, and thereby threaten the reliability of a rapid emergency response. To ad- dress these concerns, ductless filtered enclosure manufacturers have engineered the use of digital control systems.
The advanced monitoring system on the ISOLA filtered chemical work- station (Mystaire, Inc., Creedmoor, NC)—the EverSafe III Touch Controller (Figure 1)—has the benefit of state-of-the-art digital sensor technology, providing highly accurate and instantaneous readings. This system continuously monitors and digitally displays the face velocity, ensuring
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Figure 1 – EverSafe III Touch Controller on the ISOLA filtered chemical workstation.
that working conditions are safe. Sophisticated sensors determine any chemical breakthrough based on the type of solvent used within the enclosure. Visual and audible alarms alert operators when airflow falls below the industry-recommended standard of 80 fpm, indicating, for ex- ample, an inoperative blower or loss of efficiency due to blocked filters. A second alarm sounds if filters are approaching saturation—allowing for replacement well before exposure limits are reached. Additional safety features include a digital display, which shows the filter type in use and the correct application for the filter; a bar graph, to indicate filter satura- tion levels; and a time display, to track the duration that the filter has been in use relative to the maximum time allowance (Figure 2).
Carbon filtration
Carbon filtration systems combine the highest level of operator safety, while protecting the lab environment from potentially harmful fumes. The systems are based on re-circulatory technology using carbon filtra- tion to adsorb and capture harmful and toxic fumes. Upon passing through a series of filters, clean air is recirculated back into the work environment rather than vented outside—with the additional benefit of reducing atmospheric pollution. There is also a cost benefit when using ductless enclosures, since there is no loss of actively heated or cooled air from the lab environment.
Different types of research incur different risks and containment re- quirements. In this regard, effective capture and filtration systems also
JUNE/JULY 2017
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