News reports have surfaced again detailing flash fires and explosions in livestock buildings while liquid pit manure was being agitated and pumped. Iowa State University Extension agricultural engineers say these episodes highlight the caution needed when agitating and pumping manure from pits beneath buildings.

Liquid manure in pits undergoes slow decomposition which creates several gases including methane and hydrogen sulfide, both of which are flammable. The rate of gas release from the manure can be drastically increased when the manure is agitated (stirred) during pumping. This increase is especially true for hydrogen sulfide, which can have a lethal paralyzing effect in addition to being flammable.

Get hints to safely empty pits here.

Source: eXtension.org