Is Your Poultry Farm Ready for Hot Weather
The following article was written by Mike Czarick,
Extension Engineer at the University of Georgia. Even
though we are well into hot weather, I thought you
would enjoy his article.
Are you ready for hot weather? One of the keys to
keeping birds cool during hot weather is making sure
that your ventilation system is in top working order
before the hot weather hits. Tunnel ventilation and
evaporative cooling systems will only work up to their
full potential if they are cleaned, inspected and
maintained. Here is a list of 13 things that should be
checked before the first heat wave of the summer.
1. Make sure that fans are clean and properly
maintained.
Are
the
fan
you
fan
fan
and
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shutters, screens and blades clean? Are any of
hub bearings in need of replacement? Unplug the
try to shake the prop. If there is movement,
want to consider replacing the bearings.
Are there any bent fan blades? Are the fan belts worn?
Even though a belt may be tight, this doesn't
necessarily mean that it doesn't need replacing. Fan
belts are designed to sit "in" pulleys and ride on
their sides. Over time the sides of the belts are worn
down as they travel through the motor and fan hub
pulleys, resulting in the belt becoming thinner. The
thinner the belt becomes the lower the belt rides in
the pulleys. This reduces the speed at which the fan
rotates. The slower the speed the lower the amount of
air the fan moves.
Is the motor pulley "V" shaped or does it have a
smooth, mirror-like finish and have more of a "U"
shape? Like fan belts, motor pulleys can also become
worn over time. A "U" shape reduces the effective size
of the motor pulley, thereby reducing fan speed and
output.
The best tool for checking to see if a fan is spinning
at the proper speed is an electronic tachometer. Fan
speed can be checked in just a few seconds and then
compared with fan manufacturer specifications. If the
fan speed is 5% below the recommended speed, the fan
belt and/or motor pulley should be replaced.
2. Make sure your houses are tight.
Close the tunnel curtain and air inlets, and turn on a
tunnel fan and measure the resulting static pressure.
The ideal static pressure is 0.20 inches; this
indicates that, for all practical purposes, the house
has no leakage. To ensure maximum bird cooling the
static pressure should be 0.13 inches at a minimum. Not
having a tight house can dramatically reduce your
ability to keep your birds cool. For instance, let's
say that it takes two of a house's eight tunnel fans to
obtain a static pressure of 0.10 inches. This basically
means that when tunnel ventilating, 25% of the fans are
pulling hot air through the cracks and not through the
house's pad system.
Repeat the static pressure test with each of the
house's tunnel fans. If the pressure decreases, it
means the fan being used is moving less air than the
first fan tested, and is in need of maintenance. If the
pressure increases, it is an indication that the
previous fan(s) tested is/are in need of maintenance.
An insect fogger can be a very useful tool in
uncovering sometimes-hard-to-find leakage areas. Close
the house tight and turn on one 48-inch fan. Stand
inside the house and have someone outside the house
walk its perimeter while fogging the side wall from top
to bottom.
3. Patch holes in dropped ceilings.
The temperature of the air in the attic of a dropped
ceiling house during the summer can exceed 130F. If
this hot air is allowed to enter a house through holes
and gaps in the ceiling vapor barrier, the temperature
difference between the fan and pad end of a house will
rise. Keep in mind that it is three to four times
easier for air to enter through a hole in the ceiling
vapor barrier than through the evaporative cooling pad.
4. Test static pressure in full tunnel mode.
Open the tunnel curtain fully; turn all the tunnel fans
on and measure the static pressure in the center of the
house. Typically, this will run between 0.08 and 0.10
inches. If the pressure is higher than 0.10 inches, it
indicates that the tunnel fans are being restricted. It
may be as simple as your tunnel curtains not being
fully opened. It could also be an indicator that the
pads need cleaning or possibly replacing. A very low
static pressure can be an indicator that the fans are
not moving the air they should.
In houses with air deflectors, static pressure
measurements (with all the tunnel fans operating)
should be taken 30 feet past the last deflector with a
magnehelic pressure gauge. Ideally, this pressure
should not exceed 0.12 inches. If the pressure is too
high, measure static pressure once more 30 feet past
the end of the tunnel curtain opening.
If static pressure is low near the tunnel curtain
opening (i.e. 0.06 inches), this is an indicator that
the deflector curtains are too low and are causing a
significant increase in pressure that the fans are
working against. Consider raising the deflectors a foot
or two. You will often find that raising deflectors
will improve air speed significantly between deflector
curtains. If the static pressure measured near the pads
is also high, it typically indicates that your pads are
dirty and are in need of cleaning.
5. Take a close look at the house's evaporative cooling
pads.
In the center of the pad system, measure the air speed
a few inches from the pad with all the fans operating
(this should be done when there is minimal outside
wind). For a 6-inch pad the air speed should be between
350 and 400 feet per minute, a 2-inch pad between 300
and 350 feet per minute and for a 4-inch pad between
225 and 275 per minute. If the air speed appears low,
take a 5-gallon bucket of water and throw the water at
the pad where you were measuring air speed. Check the
speed of the air coming through the pad once again. If
the air speed increases, the pads are in need of
cleaning. Another sign that your pads require cleaning
is if the static pressure increases more than 0.01
inches when they become wet. If the air speed is higher
than the values noted above, you may not have enough
pad on the house.
Make sure the water in the sump is low enough so the
pads are not sitting in water when the system is not
operating. This will tend to make the bottom of the
pads soft, resulting in them possibly falling out of
the system.
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Measuring air speeds across the cooling pads can give
an indication of whether or not the pads need to be
cleaned.
6. Clean the evaporative cooling pad distribution
system.
Make sure the holes in the water distribution pipe are
clean to ensure maximum water flow over the surface of
the pad can be achieved. Water flowing over the surface
of the pad helps to keep the pad clean, eliminates
streaking, minimizes mineral buildup and, therefore,
maximizes cooling. Keep in mind that water flowing over
the surface of a pad has negligible effect on static
pressure and does not affect the air moving capacity of
your fans.
7. Clean evaporative cooling pad sumps.
Dirt at the bottom of evaporative cooling pad sumps
provides food for algae and encourages its growth. Make
sure the sump pump screen is clean and that the
impeller is not damaged.
8. Check your house air speed.
Approximately 100 feet from the tunnel fans, measure
the air speed 5 feet off the floor roughly halfway
between the side wall and the center of the house. Make
sure the air velocity meter you are using has an
averaging feature and wait at least 30 seconds before
noting the air velocity. Turn the meter off and back on
and repeat the measurement. Repeat this process on the
other side of the house and average the four readings.
This should provide a fairly accurate measurement of
average house air velocity. Ideally, the average air
velocity in a tunnel-ventilated broiler house should be
between 500 and 600 feet per minute. If it is low, and
you have taken all the above steps, you may not have
enough tunnel fan capacity to obtain optimal bird
cooling. In houses with air deflectors, air velocity
measurements should be taken halfway between deflectors
roughly 100 feet from the tunnel fan end of the house.
9. Check your water system.
If you have a 6-inch pad system, turn off the water
running to the pad system reservoirs. Empty the
reservoirs in all the houses. Turn the water back on to
all the pad system reservoirs. Can you maintain 40psi
where the water comes into the house? If not, you may
not have sufficient water capacity or the size of the
pipe running from the well/street may not be large
enough.
10. Service your standby generator.
Have the fuel/air filters been changed recently?
Is the battery charging properly?
Do you have adequate fuel on hand?
Has the tightness of electrical connections at
generator and transfer switches been checked?
Have you been exercising your generator on a regular
basis?
11. Check your farm's wiring and breaker boxes.
You may want to consider having an electrician check
your farm's electrical system. An electrician can check
for common electrical problems like poor electrical
panel connections, overloaded circuits, grounding
problems and generator sizing problems.
12. Make sure that you have spare parts.
You should have spare fan belts, motors, fogging
nozzles, PVC pipe fittings, water filters and circuit
breakers on hand. Equipment never seems to break down
between 8:00 a.m. and 5:00 p.m. Monday through Friday.
Keeping spare parts at hand will save you trips to town
and the frustration of having to wait for the supply
store to open.
13. Check back-up generator and alarm system.
Test your generator and alarm system on a regular basis
to make sure they are working properly.
-James Parsons
Area Specialized Agent, Poultry
NC State University, College of Agriculture and Life
Sciences
NC Cooperative Extension, Duplin County Center
P. O. Box 949
Kenansville, NC 28349
Phone: 910.296.2143
Fax: 910.296.2191