AAF International SAH - Manual (Page 18)

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5.10.4 Duct and System Integrity: Examine the entire system to
ensure that contaminated air cannot leak around the filter system.
Check all perimeter seals and repair as necessary.
5.10.5 Corrosion: If metal components are corroded repair the
corrosion and provide protective coatings as necessary. Be mindful
of the impact of painting on the performance and life of the gas-phase
chemical filters and take appropriate precautions to protect the
system. Determine the source of the corrosion and rectify.
6.0 Troubleshooting
6.1 High Pressure Drop Reading Across the Filter System:
6.1.1 High Dust Loading: The most probable cause of high
pressure drop will be high dust loading of the particulate filters.
The rate of dust loading may not always be constant and may be
significantly affected by season and location, e.g. the timing of pollen
blooms, production schedules, and rural versus urban locations.
6.1.2 High Airflow Volume: High airflow volume may result from
improper fan sizing or improper control of the fan. When clean
particulate filters are installed in the system the pressure drop across
the system will decrease and the airflow will normally increase. The
airflow should be controlled through the use of modulating dampers
which are designed to keep the system pressure constant or with the
use of variable speed drives. The filter system may also be slightly
oversized so that it will handle the higher airflow at the lowest system
pressure without exceeding the recommended filter face velocity.
6.1.3 Condensation: Humid air combined with cold surfaces may
result in condensation of moisture and blinding of both the
particulate and gas-phase filters. This moisture can also result in
mold growth and corrosion which may also impact the performance
of the filter system. If condensation is a recurring problem
dehumidification or other tempering of the air may be required.
Additional system insulation may also be necessary. If the source of
the moisture is at the intake, weather hoods, or weather louvers to
remove sensible moisture in the form of rain should be considered.
If the source of moisture is from leaking ducts repair the leaks.
6.1.4 Freezing: On air intake systems the presence of moisture in the
filters when caused by or combined with condensation, rain, snow,
sleet, or ice, and when subjected to freezing temperatures, can cause
the filters to freeze and become impassible. In such cases provide
intake protection systems to remove the cause of the problem.
6.2 Visible Discharge of Particulate:
6.2.1 Check for missing or damaged filters and system leaks.
Replace filters and reseal as necessary.
5.7 Gas-phase Chemical Filter Cassette Face Sealing Gaskets:
The proper maintenance of the hollow core gaskets located in the
track on the leaving air, or sealing, face of each cassette is critical to
the performance of the system. Check the gaskets carefully whenever
the gas-phase chemical filters are replaced. If gaskets are worn,
frayed, or damaged in any way they should be replaced. Check the
seal between the gas-phase chemical filter cassette and the hollow
core gasket on the air leaving face of the gas-phase cassettes
whenever new SAAF Cassettes are installed.
5.8 After-Filter and High Efficiency Particulate Filter Sealing
Gaskets: The proper maintenance of the hollow core gaskets located
in the after-filter and high efficiency particulate filter tracks are critical
to the performance of the system. Check the gaskets carefully
whenever the after-filters and high efficiency particulate filters are
replaced. If gaskets are worn, frayed, or damaged in any way they
should be replaced. Check the seal between the filters and the hollow
core gaskets whenever new particulate filters are installed.
5.9 Access Door Sealing Gaskets: The proper maintenance of the
access door sealing gaskets is critical to the performance of the
system. Check the gaskets carefully whenever the gas-phase
chemical filters are replaced. If gaskets are worn, frayed, or damaged
in any way they should be replaced. Check the seal between the door
and the housing whenever new SAAF Cassettes are installed.
5.10 General System Maintenance: Ducts, external SAH surfaces,
access doors, and other system infrastructure should be checked at
least every 6 months. Internal SAH surfaces shall be examined
whenever filters are replaced. Examine all components for the following:
5.10.1 Cleanliness: Sweep and vacuum all standing dust or dirt in the
system and damp wipe all surfaces. Be mindful of the impact of
cleaning solvents on the performance and life of the gas-phase
chemical filters and take appropriate precautions to protect the system.
5.10.2 Water: The system should be completely dry at all times.
The presence of standing water, condensation, or dampness is
detrimental to the performance and life of the system. Determine
and remove the cause for the presence of water in the system, dry
the system, and examine all components for the presence of mold
and other biological growth. Remove all contamination, clean, and
sterilize as necessary.
5.10.3 Filter System Integrity: Ensure that all filter frames contain
the appropriate filter elements, both particulate and gas-phase, and
that these elements are correctly installed. Check for missing or
improperly installed components and review the filter seals. Check
for air leaks at joints and seams and replace gaskets, worn
hardware, and seal with caulk as necessary.