Laboratories Pose Special IAQ Challenges

Arguably, formaldehyde can be considered to be one of the most prevalent contaminants present in laboratory air. Its use is widespread in most laboratories in North America, notwithstanding the fact that it is a confirmed carcinogen and well-known irritant. Furthermore, prolonged exposure to formaldehyde can cause hypersensitivity.

The University of Ottawa had a specific problem related to formaldehyde removal. The Gendron Hall Building, located on the university's campus, housed a dissection room that exceeded the time-weighted average (TWA) set by the American Conference of Governmental Industrial Hygienists (ACGIH) for formaldehyde. The main activities in the biology lab involved dissection of specimens for learning purposes in undergraduate studies.

Superior Air Quality At Minimal Cost

Traditionally, dilution ventilation techniques would be used to reduce the steady-state concentration of most gases emitted within a laboratory space. Laboratories of this type are generally maintained under negative pressure, and the combination of lab exhaust hoods with make-up air is used to control the migration of contaminants to other spaces within the building.

The dissection room at Gendron Hall, however, had a problem controlling the amount of formaldehyde vapor that was emitted into the lab space. This vapor, along with some other organic compounds, was exfiltrating into other parts of the building, causing discomfort for the occupants of the adjacent offices.

The engineers involved with this project explored two options to correct the problems. The first option was to increase the total lab exhaust rate and proportionally increase the amount of make-up air that would be provided to the space. The retrofit requirements for this method would be to replace existing exhaust and air-handling equipment so as to accommodate the new increased airflow. Subsequently, a dramatic increase in energy consumption would exist as a result of preheating of the additional make-up air.

The second option centered on the use of Circul-Aire's APS-3000 air purification system, designed in combination with potassium permanganate media to recirculate lab air within the space. The goal was to remove formaldehyde vapor while significantly reducing the energy requirement that would normally be associated with traditional ventilation techniques.

The APS-3000 system incorporates a prefilter with an average efficiency of 30 percent, two chemical media stages of MM-1000 (potassium permanganate), a 30-percent-efficiency after-filter, and, as a final stage for particulate removal, a 90-percent efficiency filter was incorporated into the system.

Circul-Aire's APS-3000 system in combination with a source capture hood system was designed to provide exceptional filtration for approximately 12 to 16 months of use, without requiring media replacement.

The maintenance of the APS-3000 air purification system has also been simplified with the Tech-Chek Service supplied by Circul-Aire. With this service, media samples are tested in order to verify consumption rates.

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This lifetime service is monitored by a computerized program from the company that indicates the appropriate schedule for media replacement. This customized service, supplied at no additional charge is designed to ensure the highest performance of the system.

For more information, visit www.circul-aire.com.

Publication date: 08/02/2004

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