§ 1060.525 How do I test fuel systems for diurnal emissions?
Use the procedures of this section to determine whether your fuel tanks meet diurnal emission standards as specified in § 1060.105.
(a) Use the following procedure to measure diurnal emissions:
(1) Diurnal measurements are based on representative temperature cycles, as follows:
(i) Diurnal fuel temperatures for marine fuel tanks that will be installed in nontrailerable boats must undergo repeat temperature swings of 2.6 °C between nominal values of 27.6 and 30.2 °C.
(ii) Diurnal fuel temperatures for other installed marine fuel tanks must undergo repeat temperature swings of 6.6 °C between nominal values of 25.6 and 32.2 °C.
(iii) For fuel tanks installed in equipment other than marine vessels, the following table specifies a profile of ambient temperatures:
Table 1 to § 1060.525—Diurnal Temperature Profiles for Nonmarine Fuel Tanks
| Time (hours) | Ambient temperature profile ( °C) |
|---|---|
| 0 | 22.2 |
| 1 | 22.5 |
| 2 | 24.2 |
| 3 | 26.8 |
| 4 | 29.6 |
| 5 | 31.9 |
| 6 | 33.9 |
| 7 | 35.1 |
| 8 | 35.4 |
| 9 | 35.6 |
| 10 | 35.3 |
| 11 | 34.5 |
| 12 | 33.2 |
| 13 | 31.4 |
| 14 | 29.7 |
| 15 | 28.2 |
| 16 | 27.2 |
| 17 | 26.1 |
| 18 | 25.1 |
| 19 | 24.3 |
| 20 | 23.7 |
| 21 | 23.3 |
| 22 | 22.9 |
| 23 | 22.6 |
| 24 | 22.2 |
(2) Fill the fuel tank to 40 percent of nominal capacity with the gasoline specified in 40 CFR 1065.710(c) for general testing.
(3) Install a vapor line from any vent ports that would not be sealed in the final in-use configuration. Use a length of vapor line representing the largest inside diameter and shortest length that would be expected with the range of in-use installations for the emission family.