Step 6	Although above the maximum operational altitude of the test item, attempt to operate the test item, making and breaking electrical contacts, such as switches, mechanical relays, and connectors as often as possible for minimum of three power/operational cycles. Continue operation from this step until completion of Step 8. Note the altitude at which the test item begins proper operation. If the test item fails to operate as intended, follow the guidance in paragraph 4.3.2 for test item failure.
Step 7	To ensure adequate mixing of the fuel and air, slowly decrease the simulated chamber altitude at a rate no faster than 100 m (330 ft) per minute by bleeding air into the chamber.
Step 8	Stop decreasing the altitude at 1000 m (3300 ft) below the test altitude or at ground level, whichever is reached first, and perform an operational check, and switch off power to the test item. If the test item fails to operate as intended, follow the guidance in paragraph 4.3.2 for test item failure.
Step 9	Verify the potential explosiveness of the air-vapor mixture as in Step 5 above. If ignition does not occur, purge the chamber of the fuel vapor, and repeat the test from Step 1.
Step 10	Adjust the simulated chamber altitude to the equivalent of 2000 m (6600 ft) above site pressure.
Step 11	Slowly introduce the required volume of n-hexane into the test chamber and begin reducing the simulated altitude at a rate no faster than 100 m (330 ft) per minute. (Note: In calculating the fuel volume to be added, providing the chamber has not been purged, subtract the volume introduced in Step 3 to maintain the proper fuel-air mixture.).
Step 12	Circulate the test atmosphere for at least three minutes to allow for complete vaporization of fuel and the development of a homogeneous mixture, and for the chamber pressure to reach the test altitude.
Step 13	At a pressure equivalent to 1000 m (3300 ft) above the site pressure, verify the potential explosiveness of the fuel-air vapor by attempting to ignite a sample of the mixture taken from the test chamber using a spark-gap device or glow plug ignition source with sufficient energy to ignite a 3.82 percent hexane mixture. If ignition does not occur, purge the chamber of the fuel vapor and repeat Steps 10-13. An alternative method of determining the explosive characteristics of the vapor is by using a calibrated explosive gas meter that verifies the degree of explosiveness and the concentration of the fuel-air mixture.
Step 14	Attempt to operate the test item and continue operation from this step until completion of Step 16. Make and break electrical contacts, such as switches, mechanical relays, and connectors as often as possible for minimum of three power/operational cycles. Note whether the test item resumes proper operation. If the test item fails to operate as intended, follow the guidance in paragraph 4.3.2 for test item failure.
Step 15	To ensure adequate mixing of the fuel and air, slowly decrease the simulated chamber altitude at a rate no faster than 100 m (330 ft) per minute by bleeding air into the chamber.
Step 16	At site pressure, perform one last operational check and switch-off power to the test item. If required, ensure the test item temperature has stabilized (in accordance with Part One paragraph 5.4.1) prior to conducting the final operational check.
Step 17	Verify the potential explosiveness of the air-vapor mixture as in Step 5, above. If ignition does not occur, purge the chamber of the fuel vapor, and repeat the test from Step 10.
Step 18	Adjust the chamber to standard ambient conditions and document the test results. See paragraph 5 of this Method for analysis of results.