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In December of
1992, the National Air Duct Cleaners Association (NADCA) adopted
NADCA Standard 1992-01, Mechanical Cleaning of Non-Porous Air
Conveyance System Components, as the first official cleanliness
standard industry wide. Soon thereafter, compliance with the
standard became a mandatory requirement of NADCA membership.
The primary
purpose of NADCA Standard 1992-01 is to define acceptable
cleanliness levels within HVAC systems immediately after
cleaning has been performed. The verification process within the
standard calls for two separate methods of inspection: Visual
Inspection and the NADCA Vacuum Test.
Visual inspection
is the primary, and in some cases may be the only, means to
verify the cleanliness of an HVAC system. There are several
methods which can be used to visually inspect an HVAC system.
Specialized tools such as boroscopes, duct scopes, mirrors, and
robots may be used for visual inspection. When performing a
visual inspection, one should look to see if there are any
visible contaminants within the system. NADCA Standard 1992-01
calls for the total removal of all visible contaminants. If
visible contaminants are present after cleaning has been
performed, the cleanliness level is considered unacceptable per
NADCA Standard 1992-01.
The NADCA Vacuum
Test serves as an additional, scientific method of determining
cleanliness within an HVAC system. If visual inspection leaves
any doubts as to the cleanliness of the system following
cleaning, the NADCA Vacuum Test may be performed to conclusively
determine the cleanliness level of a specific area. Basically,
the NADCA Vacuum Test physically determines the amount of debris
within a given surface area of the HVAC system. This amount must
be equal to or less than 1mg/100cm2.
NADCA Standard
1992-01 is designed to allow for the sampling of a given surface
of an HVAC system after cleaning, in order to determine if the
amount of remaining debris is acceptable. Within the standard,
the term debris is defined as "any solid materials,
including particulate substances, in the air conveyance system
not intended to be present." However, the standard does not
apply to hazardous materials, such as lead, asbestos, or
volatile organic compounds (VOCs).
NADCA Standard
1992-01 does not apply to porous HVAC system components, such as
fiber glass, concrete or drywall. NADCA is in the process of
developing an additional standard for verifying the cleanliness
of porous HVAC system components.
As with porous
materials, NADCA Standard 1992-01 does not apply to microbial
contamination, which, depending on the type of microbe, may be
considered a hazardous material.
NADCA Standard
1992-01 also contains general requirements relevant to the
cleaning process itself. Such requirements include provisions
for protecting the HVAC equipment, controlling particulate
debris originating in the HVAC system, testing of air duct
cleaning equipment, worker protection, proper procedures for
gaining access into HVAC systems, and methods for verifying the
acceptable cleanliness levels of coils.
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