Caleffi DirtMag Pro magnetic dirt separator for hydronic heating systems This is not for potable water systems. This dirt filter is solid brass and capable of handling high temps and pressures if needed. There are no major potential leak paths like other magnet filters. The dirt separation happens because of the slowed velocity in the bell housing. The coalescing media and magnets capture debris and ferrous material, that debris drops to the bottom of the bell housing and can be flushed out the