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Published byTrevor White Modified over 6 years ago
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Conversion (Photo Catalytic Oxidation) Technology
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Why Now? ASHRAE’s Position Introduction Conclusions
On June 24, 2009, ASHRAE’s Board of Directors approved a position document on Airborne Infectious Diseases.(18) The document was written by a committee of engineering and health professionals from around the world. The committee examined available information on the health effects of exposure to airborne infectious diseases and the implications of this information on the design, installation, and operation of HVAC systems. CLCH-PRB023-EN 9 Introduction The paper discusses three methods of disease transmission: Direct contact, large droplet contact, and droplet nuclei inhalation. It acknowledges that the HVAC professional is likely to have direct influence only on the transmission of droplet nuclei. As contact transmission control procedures, such as hand sanitizers and masks, become more commonly used, the transmission of airborne droplet nuclei by natural air currents and HVAC systems will receive more attention as an important pathway of airborne infectious disease. ASHRAE’s position is that: • • Many infectious diseases are transmitted through inhalation of droplet nuclei. • • Droplet nuclei can be disseminated through building ventilation systems. • • Airborne infectious disease transmission can be reduced by using dilution ventilation, inroom flow regimens, room pressure differentials, personalized and source capture ventilation and air cleaning. ASHRAE recommends that further research be conducted on the development of more engineering control strategies to reduce infectious disease transmission. In the meantime, it seems practical for design professionals to understand and consider the control measures available today, including dilution ventilation, space pressure differential, and air cleaning. Conclusions A common finding of recent research is that a significant amount of infectious particles are less than 4 mm in size. Particles of this size can remain suspended in indoor air for long periods of time and be recirculated throughout the building by natural air currents and the HVAC system (see Table 1, p. 7). This validates an airborne disease transmission path that is not being adequately addressed by the surface and close-contact precautions being used today. Based on research findings and on ASHRAE’s position, it seems prudent for infection-control professionals and building designers to consider additional control measures for airborne transmission, in addition to the precautions already in use when designing new healthcare facilities and updating existing facilities.
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Uses: To convert Volatile Organic Compounds To reduce airborne biological contaminates
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Photocatalysis Process
Conversion Redox reaction: A reaction in which electrons are transferred from a donor (the reducing agent) to an acceptor molecule (the oxidizing agent) Photocatalysis Process
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What is Photocatalysis? The Oxidation of Carbon using Hydroxyl Radicals
Filtration has been in common use for many years – PCO is not filtration (Capture). PCO does not capture Photolysis is understood and used in multiple applications throughout the world – PCO is not Photolysis (Cleaning surfaces) PCO does not clean surfaces - (the UVC lamps used for energy will clean exposed surfaces) Photocatalysis (PCO) using a semi-conductor such as titanium dioxide (TiO²) has been known and pursued for at least twenty-five years but it has application and production constraints PCO produces Hydroxyl Radicals Photo Catalytic Oxidation is a Conversion Process Conversion = Reduction of Organic Contaminants (lower energy cost) vs Dilution by introducing ODA (issues: equipment sizing, energy costs and pollutant introduction) Challenges with capture alone: Pressure Space Energy Cost Sustainability 5
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What is Conversion? The Oxidation of Carbon
The Reduction of Volatile Organic Compounds Destruction of Cellular Structure of Pollen, Mold, Bacteria and Virus Production of H20 and CO2 Note: PCO is not a scavenger technology The oxidizing agent is not broadcast into the space.
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What is that thing that looks like a filter with a light in it?
Think of my car’s Catalytic Converter Mechanical Reduction Device
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This is a Filter with Light? Are all PCO products the same?
Advantages: Low Static Pressure Drop Smaller AHU Life Cycle Destruction or Conversion Difference: Dwell Time Energy Distribution Self- Renewing Caution: Does the product produce harmful intermediaries? PCO completes the IAQ Puzzle 9
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Testing to be sure RTI AO3230902 – LBNL58936 Results
In conclusion, the Office Mixture was introduced into the Populated Catalyst Panel Air Cleaner at three air flow rates. Sampling for aldehydes and volatile organics showed no statistically significant production of aldehydes or VOCs at the α = 0.05 level except for a small increase in acetone at one flowrate. Bacillus atrophaeus Anthracis, Staph, E. Coli, -Aspergillus, MS2 Virus, - TB,Cladosporium -VOCs - Mold in a VA Hospital -Aspergillus Niger, MS2 Virus, Bacillus Subtilus stimulate for (Anthrax) -VOCs University of Cincinnati Environmental Tobacco Smoke MEK/Methanol Reduction Thermal Oxidizer Checking for production of by-products RTI International R Keith Esch, Ph.D Microbiologist G.D. Air Testing, George Dai, Ph.D HRA Environmental, Dr. Hamid Arabzadeh, MS, CIH, CSP, REA, CHMM U.S. Army Developmental Test Command - Dugway Proving Ground Douglas A. Tamilio LTC, IN Commander, West Desert Test Center Prism Analytical Technologies Randall S Fike, Ph.D Quality Environmental Services Joe Boatman, Ph.D Eastmount Environmental Services LLC Thomas G. Hopper, PE RTI International Kathleen Owen, Chemical Engineer
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Types of testing: Recognized third party
National Labs / Published Papers Protocol: Device on and off – establish baseline With and Without pre-filter Recirculated and Single pass (500fpm.) Agents: Those that will not commit suicide in an air- stream Case Studies / Published Reports
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Concentration Reduction
By Conversion (500fpm.) IMPORTANT NOTE: Even without filtration, PCO shows a reduction in microbial contaminants! 12
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Mechanical Dilution by Conversion
“As designed and tested the PCO system was able to remove or neutralize better than 98% of the airborne material as it processed the test chamber.” Dugway Proving Grounds Western Desert Test Center (2006). WDTC-TR ,3.8,33.
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Dugway and Bio-graphs
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Will PCO Work ? Inorganic - No Organic - Yes Best use:
Reduction of VOC’s Reduction of Airborne Biohazards
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