In Spark test, AC or DC equipment is related which has a broom. The surface from the reactor that has a glass lining is brushed employing a broom. If a defect or weakened part is available in connection with the broom, it generates a spark as being the weakened section https://ricardoprqnn.wikibriefing.com/2763511/the_basic_principles_of_glass_lined_reactor_maintenance