An Introduction to GasPhase Filtration

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Energy Savings by Integrating a Total Filtration
Strategy in HVAC

• Brian Monk, P.Eng.
• Carrier Corporation
• ASHRAE DL

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Energy reduction using a strategic filter
selection

• Reduce O.A. required
• Minimize pressure drop increase from dirt build
  up in AHU
• Properly cleaned air can be re-circulated if O.A.
  is deemed deficient

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Pertinent Standards Adopted by Many Building Codes

• ASHRAE Standard 62.1, Ventilation for Acceptable
  Indoor Air Quality
• ASHRAE Standard 90.1, Energy Efficient Design of
  New Buildings Except New Low-Rise Residential
  Buildings

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ASHRAE 62.1-2007

• Prescriptive standard which dictates minimum
  amounts of outdoor air to maintain acceptable
  indoor air quality within a space.

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ASHRAE 90.1-2001

• A standard which provides minimum energy
  efficiency requirements for the design and
  construction of new and existing buildings.

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Pertinent Excerpt from 90.1

• 6.3.6.1 Exhaust Air Energy Recovery
• Individual fan systems that havea design supply
  air capacity of 5000-CFM or greater and have a
  minimum outside air supply of 70 or
  greatershall have an energy recovery system with
  at least 50 recovery effectiveness.which
  shall mean a change in the enthalpy of thesupply
  equal to 50 of the difference between the
  outdoor air and return air at design conditions.

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Filtration CommitteesTC 2.3TC 2.4TRG. UVGI

• TRG. BCBR Blast, Chemical, Biological
  Remediation

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History
The revised Standard 62-1981, "Ventilation for
Acceptable Indoor Air Quality" recommended
outdoor air flow rates for smoking-permitted and
for smoking-prohibited conditions in most spaces.
The 1981 standard also introduced an alternative
air quality procedure to permit innovative,
energy-conserving ventilation practices. The
alternative procedure allowed the engineer to use
whatever amount of outdoor air he deemed
necessary if he could show that the levels of
indoor air contaminants were held below
recommended limits.
Key excerpts from ASHRAE Standard 62-2001
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History
The revised Standard retains the two procedures
for ventilation design, the Ventilation Rate
Procedure and the Air Quality Procedure. The
goals of achieving acceptable indoor air quality
and of minimizing energy consumption appear to
imply a compromise. An interdisciplinary
committee of engineers, architects, chemists,
physiologists, product manufacturers and industry
representatives has endeavored to achieve the
necessary balance between energy consumption and
indoor air quality in this Standard.
Key excerpts from ASHRAE Standard 62-2001
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Filtration Document is a Companion Document
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Ventilation Load Index (VLI)
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A chemical, biological, or radiological airborne
threat can come from a wartime attack, terrorist
attack, or from an industrial accident Industria
l accidents To provide collective protection for
a facilityclosing the O.A. intakes during a
release, or protecting the air intakes with a
filtration system is required. Terrorist
Threat For facilities that require continuous
operation during a short duration with little or
no warning, such as a terrorist attack,
continuous filtration of the ventilation air
intakes is required. Key excerpts from Design
of Collective Protection Shelters to Resist
Chemical, Biological, and Radiological Agents
(U.S. Army Corps of Engineers, Feb.1999)
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Class II Filtration with little or no
pressurization This class of protection is
applicable to a terrorist attack with little or
no warning that produces a short duration
small-scale release of agent. Outdoor air intakes
will be protected by continuously operating
filtration units.. The filtration system will
be sized for the normal facility air intake
requirements and need provide little or no
facility overpressure. Toxic-free Area
Overpressure The TFA will be designed for a
minimum overpressure goal of 0.02 wg. Key
excerpts from Design of Collective Protection
Shelters to Resist Chemical, Biological, and
Radiological Agents (U.S. Army Corps of
Engineers, Feb.1999)
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outdoor source controlAmbient Air Quality

• Regional outdoor air quality must be evaluated

ASHRAE Std 62-2004 4.1 Regional Air Quality.
The status of compliance with national ambient
air quality standards shall be determined for the
geographic area of the building site. In the
United States, compliance status shall be either
in attainment or non-attainment with
...NAAQS
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Space Ventilation Rates

• Table 2 prescribes rates (Rp cfm/p, Ra cfm/sf)

6201(visitor)Rp cfm/p 20 15 15 0 15
62-01 (visitor)Ra cfm/sf 0 0 0 0.3 0

• Space Type
• Office _at_ 5p/1000 sf
• K2 Classroom _at_ 25p/1000 sf
• Lecture Classroom _at_ 65p/1000 sf
• Retail Sales _at_ 15p/1000 sf
• Auditorium _at_ 150p/1000 sf

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Emission Trends (1970-1995)
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Emission Trends (1970-1995)
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outdoor source controlIntake Separation

• Should separate intakes from strong outdoor
  sources
• Currently, no requirements
• In the future, minimum separation distance from
  intake for specific outdoor sources
• Dumpster -- 15 ft
• Cooling tower exhaust -- 25 ft
• Loading dock -- 25 ft

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6.2.1 OUTDOOR AIR TREATMENT
If Outdoor Air is judged to be unacceptable in
accordance with Section 4.1 (National Ambient Air
Quality Standard), each ventilation system that
provides outdoor air through a supply fan shall
comply with sections following. Key excerpts
from ASHRAE Standard 62-2004
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National Primary Ambient- Air Quality Standard
(for O.A. as set by the US EPA)
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6.2.1.3 Other Outdoor Contaminants
When the building is located in an area where the
national standard for one or more contaminants
not specifically addressed in Section 6.2.1 is
exceeded, any design assumption and/or
calculation related to the impact on indoor air
quality shall be included in the design
documents. Key excerpts from ASHRAE Standard
62-2004
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5.17.2.1 Air Cleaning
If air leaving a space or location passes through
an air-cleaning system, the cleaned air may be
reclassified to a cleaner classification, using
the subjective criteria noted above, with the
approval of the authority having
jurisdiction. 5.17 Air Classification and
Recirculation Key excerpts from ASHRAE Standard
62-2004
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Filtration

• For cleanliness, must filter at MERV 6 or more
  upstream of wet equipment

Std 62-2004 5.9 Particulate Matter Removal.
Particulate matter filters or air cleaners having
a minimum efficiency reporting value (MERV) of
not less than 6shall be provided upstream of
all cooling coils or other devices with wetted
surfaces...
G
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Recirculation with Filtration

• Outdoor Air is not always acceptable
• The use of Outdoor Air for Dilution ventilation
  is not possible when contaminants in O.A are
  above odor threshold or TLV.
• Properly cleaned air CAN be recirculated using
  the Air Quality Method Section 6.3 ASHRAE Std.
  62-2004

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AHU Design
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MERV Ratings for Particle Filtration
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Operating Cost
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Air Contaminant Sizes
SCAN. ELEC. MICROSCOPE
OPT. MICROSCOPE
EYE
SMOG
FUMES
DUSTS
SPORES
TOBACCO SMOKE
BACTERIA
HUMAN HAIR
VIRUSES
MOLECULES
POLLEN
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High Efficiency Gas Absorbers

• POTASSIUM IMPREGNATED ALUMINA

• COAL BASED ACTIVATED CARBON

• ACTIVATED CARBON IMPREGNATED WITH PHOSPHORIC
• ACTIVATED CARBON IMPREGNATED WITH POTASSIUM
  HYDROXIDE

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Removal Mechanisms

• ADSORPTION
• ABSORPTION
• CHEMISORPTION
• CATALYSIS

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Properties of a Good Adsorbent

• Adsorptive Properties
• Substrate Surface Area (BET N2)
• Substrate Carbon Tetrachloride (CTC Activity)
• Capacity

• Physical Properties
• Hardness
• Bulk Density
• Pressure Drop

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Pore Structure

• Macropores (r gt 25 nm)
• Used to enter
• Mesopores (r 1-25 nm)
• Used to transport
• Micropores (r lt 1 nm)
• Used to adsorb

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Adsorption IsothermActivated Carbon vs General
HC
100.00
10.00
1.00
Cubic feet of Activated Carbon at 1000 CFM
0.10
0.01
0.00
1
10
100
1000
Operation Time, days
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Pressure Drop

• Pressure drop refers to the difference in
  pressure across a media bed, usually expressed in
  inches of water per bed depth.
• The most important physical characteristics
  related to pressure drop are size and shape of
  the granule.
• Pressure drop does not increase across a media
  bed as air is being purified.

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Properties of Sorbent Materials
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Chemisorption

• Oxidation Reaction
• Oxidant Contaminant Oxygen Carbon
  Dioxide Water
• Acid-Base Reaction
• Acid Base Salt Water

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Adsorption Wave
T1
T2
T3
Unused Media
Unused Media
Unused Media
Active Media
MTZ
Active Media
MTZ
Active Media
MTZ
Spent Media
Spent Media
Spent Media
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Residence Time, TRS

• The superficial amount of time that an air-stream
  is in contact with the chemical media.
• Ft3 of Media
• CFM

TRS
x 60
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FLOW SCHEMATICTHIN BED SYSTEM (TRS L.T. 0.4s)
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FLOW SCHEMATICDEEP BED SYSTEM (TRS G.T. 0.4s)
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FRONT ACCESS FILTRATION SYSTEM

• FEATURES
• Continuous Filtration
• Single or Multi-Pass Applications
• New or Retrofit Applications
• Available For Field Assembled Banks

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THIN BED Filtration SYSTEM

• FEATURES
• High Sealing Integrity
• Size Flexibility
• Multiple Stages of Particulate and Gas-Phase
  Filtration
• Optional Bi-Polar Ionization Section

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BI-POLAR IONIZATION (BPI) TECHNOLOGY

• BPI delivers ionization energy to force existing
  electrons out of a neutral gas molecule. This
  produces an ion pair which consists of a detached
  negative ion and a resultant positive ion.

Shown BPI tubes with voltage regulators.
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CORONA DISCHARGE

• The discharge of electricity, which causes a
  faint glow adjacent to the surface of an
  electrical conductor.
• Indicates the ionization of oxygen and the
  formation of ozone in the surrounding air.

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THE EFFECT OF CHARGED ELECTRIC FIELDS ON CHEMICAL
MEDIA PERFORMANCE

• Enhanced Removal Efficiency
• Increased Adsorptive Capacity

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ENHANCED ADSORPTION OF CHARGED GASEOUS
CONTAMINANTS
charged gaseous contaminants
ion generation
carbon surface
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BREAKING-DOWN MULTIPLE BONDS IN COMPLEX
HYDROCARBONS
complex organic molecules
simpler organic molecules
energy input
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SAMPLE REACTION
TWA 2 PPM STEL 5 PPM
(Hydrogen Sulphide)
(Sulphur Dioxide)
TWA 10 PPM STEL 15 PPM
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UVGI on coil surfacevs UVGI in air stream
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CASE STUDYSmithsonian National Museum of
American HistoryOutdoor Air Purification - Thin
Bed System

• Location Washington, D.C. (USA)
• Objective Protection of the Star Spangled
  Banner
• Equipment Custom AHU

• Outdoor air filtration to remove harmful
  pollutants such as NOx, SOx, O3 and HC

• Presurization of protected space using O.A.

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CASE STUDYHarrahs Casino, Lake Tahoe, NVThin
Bed Air Purification System

• Problem Environmental Tobacco Smoke
• Solution Minimize the amount of O.A. required
  for dilution by Filtration/Recirculation
• Equipment Custom AHU

• Eliminate both particulate and gaseous components
  of ETS
• Minimize the effect of second hand smoke on the
  non-smoker
• Meet the objectives of local codes and
  regulations

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CASE STUDYGeorge Bush Presidential Library
Museum, TX.Gas Phase Filtration for Libraries
and Museums

• Problem Preservation of Artifacts/ Documents
• Solution O.A /R.A Air Filtration
• Equipment Custom AHU

• Outdoor air filtration to remove harmful
  pollutants such as NOx, SOx, O3 and HC

• Reduce O.A. by improving filtration in R.A.

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CASE STUDYNew Midfield Concourse Facility,
Dulles Int. AirportOutdoor Air Filtration - USAH
with Bi-Polar Ionization

• Location Washington Dulles International
  Airport
• Objective Outdoor Air Filtration
• Equipment Custom AHU

Key Contaminants ? NOx ? SOx ? HC ? PM-10
Filter Selection Custom media blend with High
Efficiency (95) particulate filtration and
Bi-Polar Ionization.
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CASE STUDY Dade County School Board, Miami Air
Purification and Energy Conservation

• Location Primary Learning Center, Miami (USA)
• Objective Meet ASHRAE 62-89 with Energy
  Conservation
• Equipment APS-400 Thin Bed System

Key Contaminants ? HC ? VOC
Filter Selection A custom blend of activated
carbon and potassium impregnated alumina.
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The HVAC system must be designed, operated, and
maintained to provide uncontaminated air to the
TFA Key excerpts from Design of Collective
Protection Shelters to Resist Chemical,
Biological, and Radiological Agents (U.S. Army
Corps of Engineers, Feb.1999)
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Infiltration Bypass

• Infiltration
• Building envelope tightness and ventilation
  control are critical
• Bypass
• Filters should be air tight
• Check gaskets and seals
• Periodically check

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References

• Schoen, Larry ASHRAE Std 62, Ventilation for
  Acceptable Air Quality. Boston Society of
  Airchitects, Chapter of AIA, May 2004
• Vasselli, John Economics and Energy in
  Buildings. Bynum Training Center, Carrier
  Corporation, NOV 2006.
• U.S. Environmental Protection Agency Office of
  Mobile Sources. Air Toxics from Motor Vehicles.
  February, 1995.
• U.S. Environmental Protection Agency Office of
  Mobile Sources. Environmental Fact Sheet -
  Adopted Aircraft Engine Emission Standards.
  August, 1994.
• 1997 Current Market Outlook - World Market Demand
  and Airplane Supply Requirements. Boeing, 1997.
• Chang, K.M., The Integration of Airport Planning
  and Environmental Assessment - A focus on Air
  Quality Analysis, 1978.
• Pant, Bhuvan C., Diesel Exhaust Irritants and
  Odorants, Materials Research, Development and
  Production Center, 1987.
• Persily, Andrew ASHRAE Standard 62.1-2004
  Introduction and Overview. ASHRAE Winter
  Meeting, Orlando , FL, Feb 2005.
• Carrier Corporation" Demand Controlled
  Ventilation System Design". Saving Energy Cost
  while optimizing Indoor Air Quality. Syracuse
  2001.
• Stanke, Dennis. System Operation Dynamic Reset
  Option, Standard 62.1-2004. ASHRAE Journal
  December 2006

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Energy Savings by Integrating a Total Filtration
Strategy in HVAC

• Brian Monk, P.Eng.
• Carrier Corporation
• ASHRAE DL