HIV Dental Clinic’s HVAC System Gets Special Design from Engineer & Contractor.
Posted: December 18, 2006
Special filtration & air changes are designed to guard against disease transmission at New York’s Albany Medical Center HIV Dental Clinic.
Because HIV patients are 100 times more susceptible to developing active tuberculosis (TB) when exposed to the airborne infectious disease, engineers designing HVAC systems for the new Albany Medical Center (AMC) HIV Dental Clinic paid great attention to air filtration and air changes.
The fact that one-third of all AIDS victims worldwide die from TB complications, according to the Centers for Disease Control and Prevention (CDC), Atlanta, didn’t go unnoticed by AMC, which is a national leader in HIV services that comprehensively include medical, dental, social, nutritional, psychological, educational and clinical research services for AIDS patients.
Consequently, AMC’s Engineering & Construction Department based the dental center’s HVAC design on recommendations from CDC’s “Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health-Care Settings, 2005,” as well as American Society of Heating Refrigerating and Air Conditioning Engineers (ASHRAE) standards.
The two most critical compliances were air changes/hr and filter media recommendations from the CDC, according to John Davidson, manager of facilities engineering, AMC. “The attention we paid to air filtration, particularly the control of infectious airborne diseases such as TB, goes well beyond what you’d see in a conventional medical out-patient setting and illustrates Albany Medical Center’s continued specialization with HIV patient care,” said Davidson.
Conventional rooms typically require six air changes/hr, however 12 air changes/hr were designed for the 1,250-square-foot HIV dental area, which comprises rooms for waiting, offices, instrument sterilization, and three dental operatories.
Filtering is provided by an APS air purification air handler package unit from the Circul-Aire Inc. subsidiary of Dectron Internationale Inc., Roswell, Ga. Circul-Aire custom designed the 2,100-cfm system to Davidson’s specifications that include a combination of ASHRAE-rated 30-percent filter, 90-percent filter, and 99.97-percent High Efficiency Particulate Air (HEPA) filters, the latter which is specifically outlined in CDC’s TB containment guidelines.
The retrofitted space design, which includes piping, sheet metal and equipment installation services by project mechanical contractor, Alltek Energy Systems Inc., Waterford, N.Y., was challenging from the aspect that AMC leases rather than owns the building. Consequently, the existing Lennox International, Dallas, Texas, five-ton conventional rooftop system supply air had to be modified instead of replaced with a system more suitable for the application. Davidson chose to isolate the space by providing an independent air supply from a dedicated rooftop unit that was routed through the filtration system and re-circulated/exhausted independently of other spaces outside the dental area.
Alltek’s project challenges involved rigging the air purification unit through tight doorways and fabricating a hanging support system for it in an enclosed ceiling space. Running ductwork and piping in a confined environment was equally challenging, according to Alltek’s sales engineer, David Legge. F.R. Foote, a Clifton Park, N.Y.-based manufacturers representative that provided vital pre-installation information confirming the unit would fit. Alltek also fabricated all sheet metal and installed Metalaire, Clearwater, Fla., diffusers and Greenheck, Schofield, Wis., exhaust fans to balance the space to Davidson’s specified negative pressure.
Besides the extensive filtration, Davidson also likes the single source responsibility of a packaged filtration system where anticipated pressure drops from HEPA filter resistance and remedying larger horsepower fans are all factory interfaced, engineered and pre-tested. Bill Mattfeld, sales engineer, F.R. Foote, helped coordinate motor horsepower and sized the equipment accordingly to accommodate expected filter resistance.
Davidson also specified pressure-differential gauges for all three filters to determine filter replacement. Both the rooftop and filter system were outfitted with flow alarms by Kot Electric, Albany, N.Y., that activate when airflow falls below specifications.
The APS system, which can also include options such as gas-phase air purification and ultraviolet germicidal irradiation (UVGI), takes the additional safeguards in airborne infectious disease transmission: 1) metal framing on HEPA filters instead of particle board framing which typically include nitrates that can nurture infectious disease spores; 2) CIRCULOK™ tracking that tightly holds the filter media frame in place with gaskets to eliminate filter bypass; 3) inner double wall lining that protects the insulation from exposure to the air stream.
The dental clinic design is just another example of AMC’s quest for excellence in providing patients a safe and healthy environment.
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