Abstract: A system for preventing backflash in a pre-mixed hydrogen burner includes a hydrogen burner including a mixture pipe connected to a hydrogen supply flow-path tube along which hydrogen is guided and a combustion air supply flow-path tube along which combustion air is guided, wherein a mixture of the hydrogen and the combustion air is combusted at a combustion nozzle end portion of a pipe connected to the mixture pipe, and a control unit configured to perform a first control to purge the pipe and to interrupt supply of the hydrogen, in a case where backflash propagates or is likely to propagate from the combustion nozzle end portion to the mixture pipe during the combustion.

Abstract: The present invention relates to a micro metal mold for manufacturing micro metal sheet products provided with a fine or micro opening(s) or an aperture(s) together with or independently of a groove(s) and/or a protrusion(s), a method for making the mold by the electroforming or electroplating method, a method for making the mold and micro metal sheet products manufactured by using the micro metal mold. According to the invention, it is possible to manufacture micro metal sheet products, provided with fine and precise dimensions of an opening(s) as well as a groove(s) and/or a protrusion(s), under a mass production.