be used to validate the analytical data.

[4.1.5 Note amended by 48 FR 49459, October 25. 1983] 4.2 Single-Point. Integrated Sampling and Analytical Procedure. 4.2.1 The sampling point in the duct shall be located as specified in Section 4.1.1. 4.2.2 Leak-check (mandatory) the nexible bag as in Section 2.2.6. Set up the equipment as shown in Figure 3-2. Just prior to sampling. leak-check (mandatory) the train by placing a vacuum gauge at the condenser inlet, pulling a vacuum of a least 250 mm Hg (10 in. Hg). plugging the outlet at the quick disconnect, and then turning off the pump. The vacuum shall remain stable for at least 0.5 minute. Evacuate the flexible bag. Connect the probe and place It in the stack, with the tip of the probe positioned at the sampling point; purge the sampling line. Next, connect the bag and make sure that all connections are tight and leak free. 4.2.3 Sample at a constant rate. or as specified by the Administrator. The sampling run must be simultaneous with, and for the same total lengh of time as, the pollutant emission rate determination. Collect at least 30 liters (1.00 ft') of sample gas. Smaller volumes may be collected, subject to approval of the Administrator. 4.2.4 Obtain one integrated flue gas sample during each pollutant emission rate determination. For emission rate correction factor determination, analyze the sample within 4 hours after it is taken for percent CO, or percent O, (as outlined in Sections 4.2.5 through 4.2.7). The Orsat analyzer must be leak-check (see Section 5) before the analysis. If excess air is desired. proceed as follows: (1) within 4 hours after the sample is taken, analyze it (as in Sections 4.2.5 through 4.2.7) for percent CO2. O,, and CO: (2) determine the percentage of the gas that is N, by subtracting the sum of the percent CO., percent O., and percent CO from 100 percent: (3) calculate percent excess air, as outlined in Section 6.2. 4.2.5 To insure complete absorption of the CO2. O,, or if applicable, CO. make repeated passes through each absorbing solution until two consecutive readings are the same. Several passes (three of four) should be make between readings. (If constant readings cannot be obtained after three consecutive readings. replace the absorbing SO. lution.) 4.2.6 Repeat the analysis until the following criteria are met: 4.2.6.1 For percent CO2. repeat the analytical procedure until the results of any three analyses differ by no more that (a) 0.3 percent by volume when CO2 is greater than 4.0 percent or (b) 0.2 percent by volume when CO. is less than or equal to 4.0 percent. Average the three acceptable values of percent CO, and report the results to the nearest 0.1 percent. 121:1574.1 4.2.6.2 For percent O,, repeat the analytical procedure until the results of any three analyses differ by no more than (a) 0.3 percent by volume when O, is less than 15.0 percent or (b) 0.2 percent by volume when O2 is greater than or equal to 15.0 percent. Average the three acceptable values of percent O, and report the results to the nearest 0.1 percent. 4.2.6.3 For percent CO. repeat the analytical procedure until the results of any three analyses differ by no more than 0.3 percent. Average the three acceptable values of percent CO and report the results to the nearest 0.1 percent. 4.2.7 After the analysis is completed. leak-check (mandatory) the Orsat analyzer once again. as described in Section 5. For the results of the analysis to be valid, the Orsat analyzer must pass this leak test before an after the analysis. NOTE: Although in most instances only CO, or O2 is required, it is recommended that both CO2 and O, be measured, and that