Final answer:
A reverse flow valve prevents a flashback from traveling back through hoses or pipes, enhancing safety in flammable gas systems.
Step-by-step explanation:
A reverse flow valve is designed to prevent the reverse flow of gases in a system, which can be essential for safety in processes involving flammable gases. It serves as a critical component to stop a potential flashback from a flame traveling back through hoses or pipes, which could cause damage or even an explosion. In applications such as welding, where gas mixtures are used to create a flame, the reverse flow valve ensures that any flame or surge in pressure does not result in an unsafe situation by traveling back to the gas source.