Q768. What types of instruments are permissible for use in detecting equipment leaks and through valve leakage in Subpart W?

A768. For conducting leak detection required by subpart W, reporters have the option to use organic vapor analyzers according to EPA Method 21, optical gas imaging instruments, infrared laser beam illuminated instruments, or acoustic leak detection devices as outlined in 40 CFR 98.234(a).   Acoustic leak detection devices are only applicable for detecting through-valve leakage (e.g., leak from open-ended line due to leak through a closed valve) and cannot be used to identify leaks from valve stems, connectors, or other components that are not related to through-valve leakage.