subpart_subject: "Calculations and Data Requirements"
section_number: "1065.659"
section_subject: "Removed water correction."
cfr_reference: "40 CFR 1065.659"
title_name: "Title 40"
title_subject: "Protection of Environment"
parts_covered: "Part 1060 to End"
revised_date: "Revised as of July 1, 2019"
publication_date: "As of July 1, 2019"
contains_description: "Containing a codification of documents of general applicability and future effect"
publication_info: "Published by the Office of the Federal Register National Archives and Records Administration as a Special Edition of the Federal Register"
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(a)If you remove water upstream of a concentration measurement, x, correct for the removed water. Perform this correction based on the amount of water at the concentration measurement, x
H2O[emission]meas, and at the flow meter, x
H2Oexh, whose flow is used to determine the mass emission rate or total mass over a test interval. For continuous analyzers downstream of a sample dryer for transient and ramped-modal cycles, you must apply this correction on a continuous basis over the test interval, even if you use one of the options in § 1065.145(e)(2) that results in a constant value for x
H2O[emission]meas because x
H2Oexh varies over the test interval. For batch analyzers, determine the flow-weighted average based on the continuous x
H2Oexh values determined as described in paragraph (c) of this section. For batch analyzers, you may determine the flow-weighted average x
H2Oexh based on a single value of x
H2Oexh determined as described in paragraphs (c)(2) and (3) of this section, using flow-weighted average or batch concentration inputs.
(b)Determine the amount of water remaining downstream of a sample dryer and at the concentration measurement using one of the methods described in § 1065.145(e)(2). If you use a sample dryer upstream of an analyzer and if the calculated amount of water remaining downstream of the sample dryer and at the concentration measurement, x
H2O[emission]meas, is higher than the amount of water at the flow meter, x
H2Oexh, set x
H2O[emission]meas equal to x
H2Oexh. If you use a sample dryer upstream of storage media, you must be able to demonstrate that the sample dryer is removing water continuously (i.e., x
H2Oexh is higher than x
H2O[emission]meas throughout the test interval).
(c)For a concentration measurement where you did not remove water, you may set x
H2O[emission]meas equal to x
H2Oexh. You may determine the amount of water at the flow meter, x
H2Oexh, using any of the following methods:
(1)Measure the dewpoint and absolute pressure and calculate the amount of water as described in § 1065.645.
(2)If the measurement comes from raw exhaust, you may determine the amount of water based on intake-air humidity, plus a chemical balance of fuel, intake air, and exhaust as described in § 1065.655.
(3)If the measurement comes from diluted exhaust, you may determine the amount of water based on intake-air humidity, dilution air humidity, and a chemical balance of fuel, intake air, and exhaust as described in § 1065.655.
(d)Perform a removed water correction to the concentration measurement using the following equation: