What type of check valves is recommended to prevent gas mixing in hoses and regulators?

Back flow prevention check valves are specifically designed to prevent the reverse flow of gases, ensuring that gas does not mix between different hoses and regulators. These valves are integral in systems where maintaining the integrity of gas types is critical, such as welding or cutting applications that use different types of gas. By allowing flow in only one direction, back flow prevention valves help safeguard the system from contamination or undesired reactions that can occur if different gases were to intermix.

In contrast, pressure relief valves are meant to relieve excess pressure, and shut-off valves are used to completely stop the flow, neither of which directly addresses the issue of preventing gas mixing. Two-way valves permit flow in both directions but do not provide the necessary safeguards to ensure that gases remain separate. Therefore, the recommendation for using back flow prevention check valves in this context is based on their specific function of maintaining gas separation and system integrity.