40 CFR § 60.204 - Test methods and procedures.
(a) In conducting the performance tests required in § 60.8, the owner or operator shall use as reference methods and procedures the test methods in appendix A of this part or other methods and procedures as specified in this section, except as provided in § 60.8(b).
(2) Method 13A or 13B shall be used to determine the total fluorides concentration (Csi) and volumetric flow rate (Qsdi) of the effluent gas from each of the emission points. The sampling time and sample volume for each run shall be at least 60 minutes and 0.85 dscm (30 dscf).
(3) The equivalent P2O5 feed rate (P) shall be computed for each run using the following equation:
(i) The accountability system of § 60.203(a) shall be used to determine the mass flow rate (Mp) of the phosphorus-bearing feed.
(ii) The Association of Official Analytical Chemists (AOAC) Method 9 (incorporated by reference - see § 60.17) shall be used to determine the P2O5 content (Rp) of the feed.