What device is used to prevent the movement of flammable cargo vapors or liquids between spaces?

Gas tight glands are critical in preventing the movement of flammable cargo vapors or liquids between spaces. These devices create a tight seal where pipes pass through bulkheads or decks, effectively isolating areas to minimize the risk of vapor leakage or liquid spills. This tight sealing is essential in maintaining the safety of tankers, preventing flammable vapors from migrating into non-hazardous areas, which could pose a serious risk of ignition.

In contrast, check valves are generally used to prevent backflow in piping systems, but they do not provide a seal against vapor or flammable liquid movement. Pressure relief valves are designed to vent excess pressure to avoid tank rupture but do not stop the movement of vapors or liquids between compartments. Float switches are electrical devices that monitor liquid levels and do not address the containment of vapors or liquids. Each of these alternatives serves a different purpose related to fluid control and pressure management but lacks the specific function of maintaining gas-tight integrity needed to prevent flammable vapor migration.