A Flame Arrestor is a static device which stops a flame entering into the storage tank or process vessel containing a flammable gas or vapour. An end -of-line type flame arrestor is fitted at the extreme downstream end of a pipeline.

The arrestor consists of a flame quenching element contained within a housing which incorporates thread or flange connections for fitting to pipework. The element is often of greater diameter than the pipework in order to compensate for pressure drop and therefore the housing is enlarged accordingly.