C NEWARK, Del. Local broiler
companies report that fuel con
sumption in the first three weeks of
January was 1.68 times higher
than it was in December based on
gallons per 1,000 birds marketed,
says E.W. Walpole, Extension
agricultural engineer with the
University of Delaware.
The severe winter is the obvious
cause, but Walpole suggests that
harsh weather only magnifies the
benefits of good management and
the penalties of poor management.
This is especially true in relation to
operating a ventilation system.
Ventilation is the controlled
exchange of polluted pen air with
clean outside air. The pollutants
produced in a broiler house are
carbon dioxide, ammonia, water
vapor, and some others in minor
quantities.
“Ammonia and water vapor are
the most troublesome and
determine the required ventilation
rate,” says Walpole. "If you
ventilate to keep ammonia at a
safe level and keep the litter moist
but not wet, you’ll automatically
care of the carbon dioxide and
vJnor pollutants.”
The other part of the picture is
the fresh air coming in. For each
amount of polluted air that is
removed, an equal amount of cold
Good ventilation takes good management
fresh air comes in to replace it.
The fresh air must be heated up to
the desired pen temperature and
this takes fuel. This is particularly
expensive when starting and this
takes fuel. This is particularly
expensive when starting new
chicks that need 90 degree
Fahrenheit temperature during
extremely cold weather.
If you’re ventilating new chicks
at 0.1 cubic feet per minute per
bird, or 100 cfm per 1,000 birds,
when the average outside tem
perature is 20 degrees Fahrenheit,
it will take about 13.5 gallons of LP
gas worth about |lO just to warm
up the incoming air for the first
week. For a 20,000 bird house this
becomes 270 gallons worth $2OO.
And if you’re ventilating at .3
cfm per bird, the numbers become
810 gallons worth $6OO. This isn’t
your total fuel cost-just that
portion due to ventilation.
The mam point, according to
Walpole, is this. If you're ven
tilating your 20,000 bird house at .3
cfm per bird when .2 cfm would be
adequate, you’re wasting |2QO
worth of fuel, or adding one cent to
the cost of producing each bird. To
your contracting company, the
addition of one cent per bird to the
cost of-production represents a lot
of money.
Overventilation wastes fuel!
This is where management enters
the picture.
A good manager knows how old
the litter is and realizes that older
litter produces more ammonia. He
uses his nose to measure the
ammonia level. If the ammonia
smell hits you as soon as you open
the door, it’s too high. What he
wants is the condition where he can
just barely smell it. A good
manager will adjust the ventilation
rate to the lowest level that will
provide adequate control.
A good manager also knows that
as he lowers pen temperature, the
amount of ammonia produced will
decrease. He may be able to
reduce the ventilation rate slightly
in the second week. By the third or
fourth week, he shold be following
the normal ventilation rate for
moisture removal. From then on
he watches litter conditions to
evaluate moisture conditions in the
house. If the litter is dry and dusty,
he reduces' the ventilation rate; if
it’s getting wet, he increases
ventilation^
"Ventilation is more than rate,
it’s a system,” says Walpole. Fans
and their controls determine the
rate and make up half of the
system. The other half is the air
inlets. The air inlets determine the
Lancaster Farming, Saturday, February 27,1982—A43
air flow patterns within the house
by their location and adjustment.
Adjustment, of course, means
management.
“If you have automatic inlet
controls, you’ve eliminated the
job. But most of our houses have
adjustable inlets which must be
managed,” he says.
If you have adjustable inlets,
Walpole prefers that they be
controlled by winches located in
the center of the house. He also
recommends investing in a
manometer. This is a device that
measures the negative pressure
that is built up when fans exhaust
air from the house. The inlets
should be adjusted to provide a
negative pressure of .06 inches
water while the fans are running.
If you don’t have a manometer,
there are some low-cost air
velocity meters available. (Check
with your serviceman.) You should
have a velocity of 600 to 800 feet per
minute through the inlets.
A good manager learns how to
adjust the inlets depending on the
number of fans running. He knows
from weather forecasts how many
fans will be running at night and
how many will be running through
the warm part of the day. He finds
time to make the necessary ad
justments at least twice a day.
HAROLD J. DIETRICH
RRI, Box 139-D. Myerstown. PA (71 7) 933-4940
Dealerships Available In Selected Areas
What about the poor manager?
The most common problem is
inlets open too wide, giving
decreased air velocity. The im
mediate result is lack of mixing of
fresh air with pen air, uneven
temperatures throughout the
house, and the development of wet
areas. To correct these symptoms
the ventilation rate is frequently
increased. This often helps, but at
the expense of the fuel bill.
Another result of inlets being
open too wide is loss of warm pen
air by chimney action while the
fans are not operating. When
ventilating by time clock some of
this loss is inevitable, but if the
openings are twice as large as
proper the heat loss will be twice
as much as necessary.
What are some other signs of a
good manager? He has made the
house as air tight as possible so all
the ventilation air must come
through the inlets where it can be
controlled. The building is well
maintained; doors fit tightly, and
the crack between the foundation
and sill has been sealed.
The good manager has clean
fans and shutters, and the fan belts
have the proper tension. He knows
if a shutter free:;''? shut (or open)
or if it doesn’t move freely because
of a mechanical defect. And he
corrects the problems as they
occur.
Good management of the ven
tilation system provides an op
timum environment for bird
growth at a minimum cost. Poor
management results in a less
desirable environment and higher
fuel bills. A final thought—if you
have ambition to be a top grower
for your company, it will only
happen if you are a top manager.