Q86. Does Tier 3 have to be used if a unit is less than or equal to 250 mmBtu per hour, but has a continuous gas chromatograph to determine carbon content?

A86. Tier 3 is not required for any unit that is less than or equal to 250 mmBtu/hr, except as otherwise specified by another part of this subpart.  However a source may opt to use Tier 3 if it has the capability of determining carbon content and (if applicable) molecular weight at the required frequency specified in §98.34(b)(3). (See §98.33(b)(3).)