Manure Manager

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Farmers should be cautious when pumping deep-pits


September 27, 2010
By Iowa State University

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September 22, 2010, Ames,
IA — Several manure pit fires and explosions were documented in Iowa last year.
Not all of these incidents happened during agitation and pumping; nor did all
of the pits have foam present when the fires or explosions happened. Iowa State
University Extension agricultural engineers say these episodes highlight the
caution needed when agitating and pumping manure from pits beneath buildings.
September 22, 2010, Ames,
IA — Several manure pit fires and explosions were documented in Iowa last year.
Not all of these incidents happened during agitation and pumping; nor did all
of the pits have foam present when the fires or explosions happened. 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 can create dangerous situations. 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 the concern
about gas release from pumping and agitation is the concern about rapid gas
release in pits with excessive foam. It is believed that pits with substantial
foam prevent the normal release of methane from the deep-pit facilities.
Captured methane can be released quickly during agitation or when other
activities such as power-washing occur, that can rapidly break the foam. The
rapid release of methane mixing with fresh air causes methane to reach the
explosive limit for methane. 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:

  • 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 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.
  • Do not agitate manure until manure has been pumped
    and level is at least two feet below the slats.
  • When agitating the 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 does not 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.

The Iowa Pork Producers
Association
has door hang tags available to Iowa pork producers and commercial
manure applicators that read “STOP Manure Agitation and Pump–Out in Progress.”
To request tags, contact the IPPA at (515) 225-7675.

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.