NFPA-99 Practice Exam

The direction of gas produced by evaporation from the secondary header in a cryogenic liquid cylinder system entering the supply system blank of the final line regulator is upstream. This means that as gas evaporates from the cryogenic liquid, it moves toward the source or back upstream in the supply line, typically towards the regulators that manage the gas distribution. In practical terms, the gas needs to flow in a direction that allows it to be controlled appropriately by the regulators in the system, ensuring that it maintains the right pressure and flow rates for safe and effective delivery. Understanding this flow direction is particularly important in the context of maintaining proper safety standards and functionality within the gas delivery system, as outlined by guidelines such as those from NFPA-99.