EPA issued a Process Safety Alert in 2007 in response to several investigations by the National Transportation Safety Board’s (NTSB) which involved the failure of excess flow valves (EFV). While EFVs are in extensive service and have prevented numerous pipe or hose breaks from becoming much more serious incidents, experience has shown that in some cases the EFV did not perform as intended, usually because of misapplication. Also, undue reliance must NOT be placed on EFVs as the SOLE or PRIMARY protection to control accidental chemical releases from tanks or piping.
Applications and Limitations of Excess Flow Valves
