Although it’s not a common occurrence, even a few reports of flash fires and explosions in hog barns should serve as an good reminder that safety is paramount any time that liquid manure is being agitated and pumped from a holding pit.

As liquid manure undergoes slow decomposition in pits, it 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 stirred during pumping. This increase is especially true for hydrogen sulfide, which can have a lethal paralyzing effect in addition to being flammable, notes Shawn Shouse, an Iowa State University (ISU) Extension area agricultural engineer.

Strict safety protocols, along with proper ventilation and agitation practices, can minimize the risk of flash fires and explosions during manure pumping as outlined in the Pork Checkoff’s Safe Manure Removal Policies fact sheet. If you experience any foaming in a manure pit, be sure to contact your local Extension Service as well for additional information and management tips.

Following these tips, offered by Pork Checkoff and ISU, can provide a good basis to improve manure-handling safety.

  • Review your emergency action plan with all workers, and have emergency contact numbers available at the site. The Pork Checkoff’s Pork Production System, available here offers tips on developing and implementing an emergency action plan. It also includes sections on hazardous gasses and fires.
  • 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 thirty 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.

In case of fire…
If a fire breaks out at your facility, remember the acronym RACE: Rescue those in immediate danger (ONLY IF YOU CAN DO SO SAFELY). Announce to others the need to evacuate. Contain the fire by closing doors and windows as you exit. Evacuate immediately. Go straight to the designated meeting spot upon evacuating the building so that your head-count leader will know that you have safely made it out of the building.