The liquid seal drum is a specially designed vessel containing a predetermined level of water in the base of the drum. The main purpose of the liquid seal drum is to stop flame propagation in the unlikely event of flashback. The liquid seal also acts as a large check valve so that gas can not travel upstream for any reason. A third function of the liquid seal is to disentrain liquid droplets. Liquid seals can be designed as independent vessels or as an integral part of flare risers.
The Sentinel flame monitor reliably provides remote flame detection up to 550 feet away, durability, ease of maintenance, and rapid response time. If the monitor detects the absence of a flame for an adjustable amount of time, a set of dry form C contacts are activated and the pilot re-ignition system is set into motion. Response times are markedly quicker than those of a standard thermocouple wince the monitor can immediately sense the loss of flame. Since the Sentinel monitors a UV spectrum specific to hydrocarbons, solar ultraviolet rays have no effect on the monitor.