Fugitive emissions, which are unintended emissions of gases or vapors from pressurized plant components, have been a key concern for operators of oil and gas, chemical and petrochemical plants as well as regulators for a long time. Fugitive emissions could be hazardous, contribute to atmospheric pollution, and could represent an economic loss for the plant. As the number of potential leak sources at large industrial facilities can be numerous and difficult to identify, controlling fugitive emissions is particularly challenging. One particularly challenging possible source of fugitive emissions is valves in general, (see Figure 1). Particularly, pressure relief valves are not exempt from fugitive emissions. Bolted and threaded components and features that constitute pressure relief valve designs suffer the same fate. Unlike manual valves, pressure relief valves are not designed with packing (or stuffing boxes) to minimize or control emissions. Another source of challenge is that, traditionally, an industry-wide acceptable standard for testing PRVs for fugitive emissions has not been established and adopted. Emerson Automation Solutions teamed up with a leading oil and gas producer and a third-party testing laboratory to embark on an industry-leading, first-of-its-kind fugitive emissions testing program for pressure relief valves. The valves that were subjected to this test program are the Anderson Greenwood pilot-operated pressure relief valves (Figure 2, left) and Crosby direct spring-operated pressure relief valves (Figure 2, right) and OMNI portable thermal relief valves.