PURPOSE: To provide titled equipment capable of varying magnetic flux density according to the type and property of fuels to make fuel cost lower and suppress pollutant generation, by setting pair(s) of magnetic poles on both side of a fuel- feed pipe and a rotatable masking shield between the magnetic poles, respectively, to enable the magnetic flux density to be finely adjusted.

CONSTITUTION: A fuel-or combusting medium-feed pipe 2 is inserted into and fixed at the center of the casing 1. On both sides of the pipe 2, one or more pairs of permanent magnets with opposite pole each other 3, 4 fixed to the casing 1 are set with one surface facing to the other in each pair. A rotatable magnetic masking shield 5 is placed between the magnetic poles 3 and 4 being fixed to the supporting plate 6. The fixing procedure is as follows: The stem 7 of the masking shield 5 with an arci-form section, projected outward from the supporting plate 6 with the pipe 2 inserted through the center hole, is fitted to the arci-form groove 8 of the casing 1 so as to be free to slide, and the end is embedded into the lug 9 of the casing 1, thus achieving the fixing.