Section 75.36 - Missing data procedures for heat input rate determinations(a) When hourly heat input rate is determined using a flow monitoring system and a diluent gas (O2 or CO2) monitor, substitute data must be provided to calculate the heat input whenever quality-assured data are unavailable from the flow monitor, the diluent gas monitor, or both. When flow rate data are unavailable, substitute flow rate data for the heat input rate calculation shall be provided according to § 75.31 or § 75.33 , as applicable. When diluent gas data are unavailable, the owner or operator shall provide substitute O2 or CO2 data for the heat input rate calculations in accordance with paragraphs (b) and (d) of this section.(b) During the first 720 quality-assured monitor operating hours following initial certification at a particular unit or stack location (i.e., the date and time at which quality-assured data begins to be recorded by a CEMS at that location), or (when implementing these procedures for a previously certified CO2 or O2 monitor) during the 720 quality-assured monitor operating hours preceding implementation of the standard missing data procedures in paragraph (d) of this section, the owner or operator shall provide substitute CO2 or O2 data, as applicable, for the calculation of heat input (under section 5.2 of appendix F to this part) according to § 75.31(b) .(d) Upon completion of 720 quality-assured monitor operating hours using the initial missing data procedures of § 75.31(b) , the owner or operator shall provide substitute data for CO2 or O2 concentration to calculate heat input rate, as follows. Substitute CO2 data for heat input rate determinations shall be provided according to § 75.35(d) . Substitute O2 data for the heat input rate determinations shall be provided in accordance with the procedures in § 75.33(b) , except that the term "O2 concentration" shall apply rather than the term "SO2 concentration" and the term "O2 diluent monitor" shall apply rather than the term "SO2 pollutant concentration monitor." In addition, the term "substitute the lesser of" shall apply rather than "substitute the greater of;" the terms "minimum hourly O2 concentration" and "minimum potential O2 concentration, as determined under section 2.1.3.2 of appendix A to this part" shall apply rather than, respectively, the terms "maximum hourly SO2 concentration" and "maximum potential SO2 concentration, as determined under section 2.1.1.1 of appendix A to this part;" and the terms "10th percentile" and "5th percentile" shall apply rather than, respectively, the terms "90th percentile" and "95th percentile" (see Table 1 of § 75.33 ).60 FR 26530, May 17, 1995, as amended at 64 FR 28604, May 26, 1999; 67 FR 40439 , June 12, 2002