Optical gas imaging instrument
(4) Optical gas imaging instrument means an instrument that makes visible emissions that may otherwise be invisible to the naked eye. (5) Repair means that equipment is adjusted, or otherwise altered, in order to eliminate a leak. (6) Leak means: (i) Any emissions imaged by the optical gas instrument; (ii) Indications of liquids dripping; (iii) Indications by a sensor that a seal or barrier fluid system has failed; or (iv) Screening results using a 40 CFR part 60, appendix A-7, Method 21 monitor that exceed the leak definition in the applicable subpart to which the equipment is subject.