ASHRAE Journal - December 2019 - 127

COLUMN HVAC APPLICATIONS

can be used to help start a high-inertia fan or keep a hightemperature fan rotating while it cools down, should also
be speciﬁed. Will the fan require frequent cleaning to
remove buildup? If yes, will this be done online while the
fan is running or during a maintenance period? What is
the cleaning medium? Air? Steam? Water?
Does the application or installation location necessitate
special protection for fan components? Perhaps the fan is
located in a humid environment or near a seashore with
a high concentration of airborne salt. If that is the case,
special paint may be necessary to protect the fan, which
should be made clear to the fan manufacturer.

Sound
Are there noise limits that must be observed? The purchaser should consider general Occupational Safety and
Health Administration limits on sound levels within and
outside a plant environment. Deﬁning acceptable noise
limits to satisfy various criteria is beyond the scope and
expertise of most fan manufacturers, so the purchaser
is encouraged to work with a qualiﬁed sound engineer.
Generally, if limits are not speciﬁed, fan manufacturers
will assume the end user has a plan to mitigate sound
once a fan is installed. Achievement of required sound
levels is possible with minor design modiﬁcations, so it is
beneﬁcial to address issues at the time fans are quoted.
Typical noise-abatement strategies include inlet and/
or outlet silencers to reduce noise being transmitted
through ductwork and proper insulation to reduce noise
transmitted through fan casings. Attenuation can be
improved by increasing casing-material thickness or
adding a fan-shaft seal.

Testing and Quality Assurance
What sort of testing is required to validate a fan?
What kind of test standard should be followed? Smaller
fans can often be run-tested in the factory at minimal
expense, providing assurance that the fan will operate
trouble-free once installed.
For larger fans, performance testing at the factory is
possible but may not be practical. If a fan is going to be
tested, the acceptance criteria should be speciﬁed or
agreed upon prior to design and construction.
Are there any special analytical requirements and
acceptance criteria, such as low-cycle fatigue or torsional critical speed? The results of these analyses can
affect material and component selection.

Spare Parts
Does the site require spare parts for the new fan?
Having items such as bearings and shaft seals on hand
can be helpful in the event of a minor upset during the
ﬁrst run. Though this may add a small cost, it will ensure
startup is not delayed.

Storage
Will the fan be installed and started right away, or will
it be stored? If it will be stored, for how long and under
what conditions? Will it be stored inside a heated warehouse or in an outdoor "laydown" area? Answers to these
questions will impact packing requirements. If the fan
is assembled, ongoing maintenance may be needed to
ensure it remains in ready-to-run condition.

To Learn More
For further information on preparing fan speciﬁcations and guidance on evaluating proposals, see AMCA
Publication 801, Industrial Process/Power Generation Fans:
Speciﬁcation Guidelines.

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