(a) The provisions set forth in this subpart apply at all times.

(b) You must not shut down items of equipment that are utilized for compliance with this subpart during times when emissions are being, or are otherwise required to be, routed to such items of equipment.

(c) Startup begins when fuels are ignited in the cupola. Startup ends when the cupola produces molten material.

(d) Shutdown begins when the cupola has reached the end of the melting campaign and is empty. No molten material continues to flow from the cupola during shutdown.

(e) During periods of startups and shutdowns you must operate your cupola according to one of the following methods:

(1) You must keep records showing that your emissions were controlled using air pollution control devices operated at the parameters established by the most recent performance test that showed compliance with the standard; or

(2) You must keep records showing the following:

(i) You used only clean fuels during startup and shutdown; and

(ii) You operate the cupola during startup and shutdown with three percent oxygen over the fuel demand for oxygen.