(a) Certification test results corresponding to manual sampling as specified in § 1090.1335(b) are valid only if collected samples meet the homogeneity specifications in this section, except that the homogeneity testing requirement does not apply in the following cases:

(1) There is only a single sample using the procedure specified in § 1090.1335(b)(2).

(2) Upright cylindrical tanks that have a liquid depth of less than 10 feet.

(3) Horizontal tanks with circular or elliptical cross section with a volume less than 42,000 gallons used for storing ethanol denaturant. Draw samples from the approximate mid-depth of the product level.

(4) You draw spot samples as specified in paragraph (c) of this section, test each sample for every parameter subject to a testing requirement, and use the worst-case test result for each parameter for purposes of reporting, meeting per-gallon and average standards, and all other aspects of compliance.

(5) Your tank configuration depends on roof sampling for homogeneity demonstration, but inclement weather prevents collecting roof samples and EPA has already approved a plan for a mixing procedure to ensure a homogeneous batch for your specific tank configuration. EPA approval of the mixing procedure will include consideration of product type, fill level, and other relevant parameters for specific tank configurations and batch characteristics. Keep records to document EPA approval of the mixing procedure, your actions to follow the approved mixing procedure, and the forcing weather event.

(6) Sampling occurs at a downstream location where it is not possible to collect separate samples and steps are taken to ensure that the batch is well mixed.

(7) The product being tested is certified butane or certified pentane.

(b) Any test to establish homogeneity is considered a certification test relative to a per-gallon standard for a given parameter if the test result is the worst-case value from all testing performed for the batch. Report the highest measured value as specified in § 1090.1335(e)(1).

(c) Use spot sampling as specified in § 1090.1335(b)(2) for homogeneity testing.

(d) Demonstrate homogeneity for gasoline and TGP using two of the procedures specified in this paragraph (d) with each sample. For summer gasoline, the homogeneity demonstration must include RVP measurement.

(1) Measure density or API gravity using ASTM D287, ASTM D1298, ASTM D4052, or ASTM D7777 (incorporated by reference, see § 1090.95).

(2) Measure the sulfur content as specified in § 1090.1360.

(3) Measure the benzene content as specified § 1090.1360.

(4) Measure the RVP as specified in § 1090.1360.

(e) Homogeneity requirements apply as follows for other products:

(1) Demonstrate homogeneity for diesel fuel using one of the procedures specified in paragraph (d)(1) or (2) of this section.

(2) Demonstrate homogeneity for certified ethanol denaturant and oxygenate based on measured sulfur content as specified in § 1090.1360, except that no homogeneity testing is required for DFE if you calculate sulfur content as specified in § 1090.1330.

(f) Consider the batch to be homogeneous for a given parameter if the measured values for all tested samples vary by no more than the published reproducibility of the test method multiplied by 0.75 (R × 0.75). If reproducibility is a function of measured values, calculate reproducibility using the average value of the measured parameter representing all tested samples. Calculate using all meaningful significant figures as specified for the test method, even if § 1090.1350(c) describes a different precision. For cases that do not require a homogeneity demonstration under paragraph (a) of this section, the lack of homogeneity demonstration does not prevent a quantity of fuel, fuel additive, or regulated blendstock from being considered a batch for demonstrating compliance with the requirements of this part. The following additional provisions apply for special cases:

(1) Do not use test results for a given test method for a parameter to demonstrate homogeneity if multiple measured values are at or below the test method's PLOQ, LLOQ, or valid range, as applicable. You may instead use a different test method as allowed under this subpart to get test results with the same parameter or with a different parameter.

(2) If you have homogeneity test results for more than the required number of parameters and not all parameters meet the criteria, all testing results except density or API gravity must meet applicable homogeneity criteria to demonstrate that the batch is homogeneous.

(3) If using ASTM D4052 (incorporated by reference; see § 1090.95) for measuring density or API gravity to demonstrate homogeneity through December 31, 2026, you may calculate the homogeneity criterion based on the reproducibility of the test method at the limit of the valid range for testing, even if measured results extend beyond the valid range. You may request to use an updated version of ASTM D4052 if the updated version has expanded the range of reproducibility to include your measured results. You may also request to use the provisions of this paragraph (f)(3) beyond December 31, 2026, if there is no updated version of ASTM D4052 with reproducibility that applies for your measured results.