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.
Continuously sweeping a stack with purge gas can result in exorbitant operating expenses over time; especially for large diameter stacks. The Molecular Seal is a purge reduction device which allows the flare system operator to use 98% less purge gas while continually sweeping the system. The savings in daily purge gas consumption over the long run makes for a short payback period on the initial capital investment of the molecular seal, which can also be referred to as labyrinth or density seal.
84-24-3974 7541 
