Check valves
Check valves are one of the most simple valve designs. Within the body of the valve, there's a slanted metal plate that opens when there is pressure on one side, or if the pressure is greater on the opposite side. This valve rests in the closed position.
The flashback arrestor is a valve is more complicated than a check valve. It is designed to have the same purpose as a check valve but with more fail-safes installed. This valve is designed to prevent flame from going from the end of a welding torch through the line to the fuel source.
The Check valve could not stop a flame from going backward through a line. The pressure of the fuel being pumped through would keep the valve open, so the fuel tank would always be vulnerable to the flame. The reason flashback arrestors were invented is to prevent these types of incidents.
