Proposed Revisions to Reference Method
EPA published proposed revisions to
Reference Method 2H in the August 25, 2009 Federal Register. The Agency
is revising Method 2H in order to harmonize the method with
Conditional Test Method 41 (CTM-041).
The proposed revisions address wall
effects for both circular stack and rectangular duct measurement
locations and extend the improvements that were included in
CTM-041 to all units.
to Method 2H will increase the accuracy of the
method and simplify its application:
Increased accuracy while
eliminating unnecessary tests. The
revisions would significantly reduce the
uncertainty of wall effect adjustment
factors (WAFs) by requiring that at least
three wall effect runs be conducted rather
than a single run as is currently allowed.
However, consistent with EPRI and EPA field
test results showing wall effects are
independent of load and do not change over
time, the revisions allows the WAF to used
for any subsequent RATAs, provided that the
same number of traverse points are use or
changes are made to the duct or stack.
Thus, while the initial effort would be
increased, the overall testing requirements
would be reduced. Do it once but do it
Decoupled from RATA.
The revised method does not need to be
coupled with a RATA, allowing sources to
avoid the potential difficulties and
problems associated with trying to measure
wall effects using Methods 2F or 2G.
By harmonizing Method 2H and CTM-041 into
one revised method covering both circular
stack and rectangular duct sources, the
reporting should be streamlined. CAMD would
no longer have to address petitions for the
use of CTM-041 and consistent reporting
could be used for both groups of sources.
The arbitrary default WAFs and cap have been
removed under from the revised method.
Instead, the revisions include options to
determine conservative default WAF values
that are based on viscous shear theory and
take into account stack/duct geometry into
A copy of the
proposed revisions to Method 2H is available in
FTP library. Comments on the proposed rule
are due by October 26, 2009. Given the
improvements to the method, RMB encourages
positive comments in support of the proposed
revisions. If you have any questions regarding
the proposed Method 2H revisions, please contact
Steve Norfleet at (919) 791-3123 or
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February 05, 2012