Hydrogen
sulfide gas continues to be a serious issue both in and around barns with
liquid manure storages. The decomposition of organic matter in manure results in the
release of several gases, ammonia, carbon dioxide, methane, and hydrogen
sulfide among them. Most
of the time these gases are emitted slowly, but any time manure is being agitated,
pumped, or the surface is disturbed, hydrogen sulfide can be rapidly released. Although all are
potentially dangerous, hydrogen sulfide tends to be the one of most concern in
these cases. Hydrogen sulfide has an intense rotten egg smell, so it is
relatively easy to detect its presence, even in very low concentrations.
However, since we can smell it at such low levels, there is not a clear
indication of when it reaches a potentially hazardous conditions that we can
detect without the use of analytical instruments.
Hydrogen sulfide can spike quickly and
without warning during pit pumping.
People should NEVER enter a building or facility
while agitation is occurring. Use yellow caution tape to mark barn entrances and
alter everyone that manure agitation and pumping is occurring. Consider lockout
tags during pumping.
If possible, remove animals before pumping. For barns with multiple
pits move cattle out of the room with the pit being agitated to reduce risk.
Agitation
Strategy
·
Don’t
agitate until manure the manure level is 1 ½ to 2 feet below the slats.
o Hydrogen sulfide is denser than air and
as a result will tend to pool on the manure surface, sufficient separation is
required to minimize hydrogen sulfide in the animal breathing zone
· Avoid aggressive agitation when animals
are in the building (no rooster tailing).
o Surface agitation causes more
turbulence and greatly increases the release of hydrogen sulfide
· Do not direct agitator
nozzles toward pillars, walls, or towards a corner.
o Pillars
and walls stop flow quickly and cause the manure to churn, increasing the rate
hydrogen sulfide is off gassed from the manure.
o Corners
are often dead air zones; releases off hydrogen sulfide in this area are more
likely to result in animal loss
· Stop agitating when bottom nozzle is
less than 6” below the manure surface.
o
Keep
the agitation below the surface at all times.
· Avoid sudden changes in agitator depth
and intensity.
o Quick changes can result in large
amounts of solids that haven’t previously been agitated and result in rapid gas
release.
o Slower changes in both power, flow
direction, and depth, allow slower, more continuous release that is safer for
animals and workers.
