The US Environmental Protection Agency (EPA) once considered dry gas seal centrifugal compressors to be low-emission sources and did not subject them to control. The final regulation issued in 2023 (NSPS OOOOb) has changed that.
The EPA acknowledges that some dry gas seal compressors emit more than people previously thought. The regulation sets a maximum leak rate limit of 10 scfm (standard cubic feet per minute) for each dry gas seal, while also requiring monitoring and repair to keep the leak rate below this level. For oil-sealed compressors, the regulation requires a 95% reduction in methane and VOC emissions from the oil drain system, or the application of corresponding limits.
On July 31, 2025, the EPA issued an interim rule extending many compliance deadlines, with many deadlines moved to January 22, 2027, and this regulation was finalized in December 2025. The EPA is also reviewing OOOOb and OOOOc in their entirety, so requirements may continue to change.
This is a US regulation, not directly applicable in Vietnam, and its effectiveness may have changed after the time of writing.
EPA (summary of requirements 12/2023, announcement 12/2025), Federal Register (12/3/2025), Compressortech2. The article was compiled and reinterpreted by SNS-VN.