(a) Periodic testing. When required by this chapter, the owner or operator of any stationary internal combustion engine shall test engine nitrogen oxides (NOX ) and carbon monoxide (CO) emissions as follows.
  (1) The methods specified in §117.8000 of this title (relating to Stack Testing Requirements) must be used.
  (2) The owner or operators shall sample:
    (A) on a biennial calendar basis; or
    (B) within 15,000 hours of engine operation after the previous emission test, under the following conditions:
      (i) install and operate an elapsed operating time meter; and
      (ii) submit, in writing, to the executive director and any local air pollution agency having jurisdiction, biennially after the initial demonstration of compliance:
        (I) documentation of the actual recorded hours of engine operation since the previous emission test; and
        (II) an estimate of the date of the next required sampling.
  (3) Engines used exclusively in emergency situations are not required to conduct the testing specified in paragraph (2) of this subsection.
(b) Proper operation. When required by this chapter, the owner or operator of any stationary internal combustion engine shall check the engine for proper operation by recorded measurements of engine NO X and CO emissions at least quarterly and as soon as practicable within two weeks after each occurrence of engine maintenance that may reasonably be expected to increase emissions, oxygen sensor replacement, or catalyst cleaning or catalyst replacement. Stain tube indicators specifically designed to measure NOX concentrations may be acceptable for this documentation, provided a hot air probe or equivalent device is used to prevent error due to high stack temperature, and three sets of concentration measurements are made and averaged. Portable NOX analyzers are also acceptable for this documentation. Quarterly emission testing is not required for those engines whose monthly run time does not exceed ten hours. This exemption does not diminish the requirement to test emissions after the installation of controls, major repair work, and any time the owner or operator believes emissions may have changed.

Source Note: The provisions of this §117.8140 adopted to be effective June 14, 2007, 32 TexReg 3206