Protectoseal Series No. 670 / 6670 End-of-Line Circular Plate Flame Arresters are installed where it is not necessary to conserve vapors but where low flash point liquids must be protected against fire and explosion from exterior sources of ignition. Standard units have NPT thread connections. The accurately spaced circular flame arrester grid plates are integral with the vent housing.

These flame arresters are mounted on the end of a vent pipe from the tank. Vapors are allowed to escape into the atmosphere and air can be drawn into the tank through the specially designed flame arrester grid assembly. If an ignition source outside the tank (unconfined deflagration) is encountered, the flame arrester provides protection for the tank's vapor space.

Suitable for Group D Vapors, such as gasoline and methane, as referenced in the National Electric Code (NEC Article 500), generally equivalent to International Electrotechnical Commission (IEC) Group IIA.