The Rural Voice, 2004-03, Page 26immediately. Researchers have
measured levels of up to 1600 ppm
of hydrogen sulfide and greater than
17 per cent carbon dioxide by using
this technique.
• Assume the gas is present even
after the manure is gone. Many
people have died entering empty or
near empty manure tanks or
spreaders assuming that the gas had
left with the manure. "Any time you
must enter a confined space where
this gas may be present, a trained
individual must wear a self-contained
breathing apparatus," Chambers says.
"Limit access to all confined spaces
at all times."
• Check the ventilation system to
verify that barn fans are pulling air
from the air inlets and not from the
manure pit. Many animal deaths
have resulted from air coming into
the barn through the manure tank
after the pit access covers are
removed or a pull plug was left open.
• Manure gas can rise around the
outside open access hole to
dangerous levels. While this may not
pose a risk while standing, if the
situation requires someone to bend
down to repair or adjust a pump
component, they may be overcome
by fumes and fall into the pit.
• Small children and pets should be
kept away during agitation and
manure removal because both
hydrogen sulfide and carbon dioxide
are heavier than air and the child or
pet might be exposed to a fatal dose
before someone taller notices.
• If something goes wrong whether it
be with animals in the barn or
someone entering or falling into a pit
or manure spreader, do not go in,
Chambers warns. Shut down the
pump if it is operating and phone the
fire department. "Under no
circumstances should you attempt to
perform a rescue. Many multiple
death have occurred as person after
person has died trying to rescue the
initial victim. The ,dangers of
hydrogen sulfide do not permit
mistakes — always assume it is
present in and around any liquid
manure storages, pumping pits or
spreaders. Make sure everyone on the
farm is aware of the dangers as well."
One of the , ways to protect
yourself, your family and staff and
your animals can be by installing a
hydrogen sulfide detector. If you buy
22 THE RURAL VOICE
one of these detectors, which are
made primarily for the oil and gas
industry, be sure to choose one that
can handle the rigors of in -barn use,
Chambers said. "The dusty, humid.
gassy environment of a swine facility
is not friendly to sensitive electronic
equipment such as a detector unless
that equipment is designed for that
situation. Consult the vendor to
question whether their product, to
which you, your family and
employees trust your lives to, is
going to function as required if the
situation arises."
"Follow the operating instructions
to the letter," Chambers advised.
"Most of these units are failsafe, but
recognize and respect any limitations
or maintenance schedule the unit may
have. Like the brakes on your truck,
it must work flawlessly when you
need it the most."
While carbon dioxide is less toxic
than hydrogen sulfide, it shares many
of the same properties. It has no
odour at any concentration and could
be fatal after a few minutes at levels
exceeding seven to 10 per cent.
"The dangers of hydrogen
sulfide do not permit
mistakes always assume
it is present..."
Levels of carbon dioxide gas have
measured to exceed 17 per cent, well
in excess of fatal levels. It has a
specific gravity of 1.53 so it is found
in the same location as hydrogen
sulfide. The levels of carbon dioxide
gas rise during agitation more slowly
than hydrogen sulfide and it requires
a longer relative exposure time to
cause death so that any precaution
you take for hydrogen sulfide should
also work for carbon dioxide.
However, if you are using a breathing
apparatus, it must be rated for both
hydrogen sulfide and carbon dioxide.
"Ignoring one or the other may
very well lead to your death,"
Chambers warned.
While ammonia can cause
respiratory spasms in levels greater
than 5000 ppm, it has several
properties that make it less dangerous
than hydrogen sulfide, Chambers
said.
The safety issue with ammonia is
one of Tong -term exposure for
humans and animals in constant
average values greater than 25 ppm.
Ammonia has a specific gravity of
0.6 so it rises into the barn space
from the manure storage. The easiest
method to maintain proper levels is
to ensure that the ventilation system
is functioning properly, Chambers
said. Levels of 30-50 ppm will cause
eye irritation.
One of the major factors that
affect production of ammonia is pH.
Liquid manure with a pH above 7.5
will cause ammonium in the manure
liquid to be converted more readily to
the gas ammonia. "If high levels of
ammonia are a concern, have the
manure tested with a pH meter,"
Chambers advised. "There are many
products on the market that cause the
pH to drop to an acceptable level."
Of the four gases most common
from manure, methane is the most
benign in terms of toxicity. It would
asphyxiate by replacing oxygen at
levels greater than 500,000 ppm but
this works out to 50 per cent of the.
volume of the air whereas hydrogen
sulfide can kill at the first breath at
just 0.1 per cent of volume.
"The main danger with methane is
with explosions," Chambers said.
"Methane is one of the main
constituents of natural gas."
It is odourless and has a specific
gravity of 0.5 so, being lighter than
air, it tends to be removed through
ventilation as the gas is produced.
The main danger is when the gas
accumulates over time in an
unventilated room over manure
storages and is exposed to a spark or
flame. All such places should be
opened up or constantly ventilated.
Chambers said.
Learn about each of these
dangerous gasses, he advises.
"Improper exposure to manure gases
can lead to injury or death of farm
workers. By knowing each of their
properties and the precautions to
take, the hazards associated with
them can be minimized."
More information can be obtained
from the Ontario Farm Safety
Association in Guelph at 519-823-
5600, from the OMAF factsheet
Hazardous Gases or from Canada
Plan Service plan M-8710 Manure
Gas by emailing
john.johnston@omaf.gov.on.ca or
telephoning 519-873-4096 and
requesting the plan.0