§ 1065.659 - Removed water correction.

§ 1065.659 Removed water correction.

Cross Reference

Link to an amendment published at 86 FR 34566, June 29, 2021.

(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, DEF, 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, DEF, intake air, and exhaust as described in § 1065.655.

(d) Perform a removed water correction to the concentration measurement using the following equation:

[73 FR 37335, June 30, 2008, as amended at 76 FR 57462, Sept. 15, 2011; 79 FR 23804, Apr. 28, 2014; 86 FR 34566, June 29, 2021]