Flame arresters designed to prevent the transmission of a deflagration fitted with two pipe connections one on each side of the flame arrester element. They are static flame arrester measurable type to be thereby charcterised by that the quenching gaps of the flame arrester element can be technically drawn, measured and controlled. It can be designed bi-directional which prevents t flame transmission from both sides. The integrated temperature sensor integrated by the manufacturer used to indicate a stabilized flame into the flame arrester.