1.1 This practice covers the procedure for certifying continuous opacity monitors. In the main part of this practice, it includes design and performance specifications, test procedures, and quality assurance requirements to ensure that continuous opacity monitors meet minimum design and calibration requirements, necessary in part, for accurate opacity monitoring measurements in regulatory environmental opacity monitoring applications subject to 10 % or higher opacity standards. In Annex A1, additional or alternative specifications are provided for certifying opacity monitors intended for use in applications where the opacity standard is less than 10 %, or where the user expects the opacity to be less than 10 % and elects to use the more restrictive criteria in Annex A1. In both cases, the error budgets for the opacity measurements are given in Appendix X1. 1.2 This practice applies specifically to the original manufacturer, or to those involved in the repair, remanufacture, or resale of opacity monitors. 1.3 Test procedures that specifically apply to the various equipment configurations of component equipment that comprise either a transmissometer, an opacity monitor, or complete opacity monitoring system are detailed in this practice. 1.4 The specifications and test procedures contained in the main part of this practice have been adopted by reference by the United States Environmental Protection Agency (U.S.EPA). For each opacity monitor or monitoring system that the manufacturer demonstrates conformance to this practice, the manufacturer may issue a certificate that states that opacity monitor or monitoring system conforms with all of the applicable design and performance requirements of 40 CFR 60, Appendix B, Performance Specification 1 except those for which tests are required after installation