Livestock producers face explosion hazards
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.
To minimize risk of injuries and flash fires, manure handlers should follow these steps:
• Review your emergency action plan with all workers and have emergency contact numbers available at the site.
• Prior to agitation or pumping, turn off electrical power to any non-ventilation equipment, and extinguish any pilot lights or other ignition sources in the building.
• Fully open all ventilation curtains or ventilation pivot-doors, but leave walk-in doors locked to prevent human entry.
• Run ventilation fans at maximum speed.
• Ensure that all people are out of the building and clearly tag all doors noting that the building is unsafe for entry during agitation and pumping.
• Agitate the manure, keeping the jet of pressurized manure below the liquid surface. Don’t let the jet of manure strike walls or columns in the pit.
• Stop agitation when the manure level does not allow agitation below the liquid surface.
• Continue maximum ventilation for 30 minutes after pumping has ended before re-entering the building.
• Never enter a building or manure storage structure when liquid manure is being agitated or pumped.
Manure gases are an unavoidable byproduct of liquid manure storage. Strict safety protocols along with proper ventilation and agitation practices can minimize the risk of flash fires and explosions during manure pumping. — WLJ