Iowa State University Extension ag engineers say cases of manure pit fires and explosions highlight the caution needed when farmers and custom manure applicators are agitating and pumping manure from pits beneath buildings. The ISU specialists offer steps you can take to minimize risk of injuries and flash fires.
Last year there were several documented cases of manure pit fires and explosions in Iowa, says Shawn Shouse, an ISU Extension ag engineer field specialist in southwest Iowa. Not all of these incidents happened during agitation and pumping, nor did all of the pits have foam present when fires or explosions happened.
Liquid manure in pits undergoes slow decomposition which creates several gases including methane and hydrogen sulfide, both of which can create dangerous situations, he explains. The rate of gas release from manure can be drastically increased when manure is agitated (stirred) during pumping. This increase is especially true for hydrogen sulfide, which can have a lethal paralyzing effect.
Caution needed when agitating, pumping manure from pits beneath buildings
In addition to concern about gas release from pumping and agitation is concern about rapid gas release in pits with excessive foam. "It's believed that pits with substantial foam prevent the normal release of methane from deep-pit facilities," says Shouse. "Captured methane can be released quickly when foam is disturbed by agitation or other activities such as power-washing. The rapid release of methane mixing with fresh air can create an explosive mixture. If this mixture comes into contact with an ignition source, it can cause a flash fire or explosion."
To minimize risk of injuries and flash fires, manure handlers should follow these steps from extension:
* Review your emergency action plan with all workers and have emergency contact numbers available at the site. The publication Emergency Action Plans has additional information.
* Prior to agitation or pumping, turn off electrical power to any non-ventilation equipment such as lights and feed motors, and extinguish any pilot lights or other ignition sources. 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. The Iowa Pork Producers Association has door hang tags available to pork producers and commercial manure applicators. To request tags, contact IPPA at 515-225-7675.
* If significant foam is present, consider pumping without agitation to reduce risk of fire or explosion, and monitor solids accumulation to decide if agitation is advised at the next pumping event.
* Don't agitate manure until manure has been pumped and level is at least 2 feet below the slats. When agitating manure, keep 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 doesn't allow agitation below the liquid surface.
Continue maximum ventilation for 30 minutes to an hour 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.
Watch video which discusses safety practices for pumping from deep pits
A video discussing safety practices for pumping from deep pits is available. "Manure gases are an unavoidable byproduct of liquid manure storage," sums up Shouse. "Strict safety protocols along with proper ventilation and agitation practices can minimize the risk of flash fires and explosions during manure pumping."
Got a question? Get it answered: The following ISU contacts (Extension ag engineers) are available to answer questions related to safety practices for pumping manure from deep pits or to answer other manure management questions.
* Shawn Shouse, 712-769-2600, [email protected]
* Kris Kohl, 712-732-5056, [email protected]
* Greg Brenneman, 319-337-2145, [email protected]
* Kapil Arora, 515-382-6551, [email protected]
* Dan Huyser, 641-435-4864, [email protected]
* Jay Harmon, 515-294-0554, [email protected]
* Steve Hoff, 515-291-2726, [email protected]