Reasons and Countermeasures of Manhole Explosion

The reason of manhole explosion caused by flammable gas is analyzed with the practical situation in Hong Kong.The flammable gas enters into the confined space of the manhole through cracks and holes in the pipe connecting the manholes,and accumulates gradually until explosive gas forms.When ignition source is contacted,a manhole explosion even a series of manholes explosion are caused.The countermeasure of plugging the pipe connecting the manholes is proposed.