Electricity failure
4
E lectricity failure is a major threat facing poultry producers. It may be a rare occurrence in countries with a good power supply system but it is a real and frequent problem in some areas. As a result, back-up electricity generators are in use on almost all farms around the world. Nevertheless, sometimes the unexpected happens - the back-up system also fails and disaster looms. A few years ago, a study was conducted on a research farm to examine the effects of an electricity failure on growing caged birds (hens) in winter when the outside temperature was below zero. Which birds were the first to be affected? What was the cause of death - carbon dioxide or ammonia build-up or excessive temperatures? It had been general practice in that region to maintain the temperature in the house by turning off the ventilation system and sealing any cracks in the building. Trial set-up To measure the carbon dioxide concentration in the poultry house, a gas collection system was fitted into poultry house, as shown in Figure 1. Five sets of filters were placed in different locations and at different heights on the cages and exhaust fan (Figure 2). Each filter was connected to a PVC tube, which was in turn connected to a main panel with valves. Each valve controlled one filter. All five tubes led to the service room of the poultry house. A vacuum compressor was connected to the main valve panel through a fin filter. The compressor pumped the air to an aquarium, which was upside-down and samples were taken from another tube placed on the base of aquarium. There was a further filter outside the poultry house to flush the system with fresh air after each sampling. The samples were analysed chemically, using a commercial colorimeter and carbon dioxide tube model 126SA with a range of 0.1-2.6%. Measurements with low readings were repeated and the average value was used. How do birds react to a power failure? After an electricity failure, the birds will initially breathe normally. When the oxygen concentration in the air begins to fall, they start to breathe more rapidly for two reasons: firstly, the temperature in the house increases because of the birds’ body heat and 28 POULTRY INTERNATIONAL SEPTEMBER 2002 Electricity failure – limiting the damage Electricity failure – limiting the damage A power cut shuts down the ventilation system, leading to a build-up of carbon dioxide and rising temperature, often with dire consequences for the birds. Regular checking and maintenance of the back-up electricity generator is essential. The author has invented a system to keep the birds more comfortable until the power supply is re-established. —Dr Dhia Alchalabi Filter Filter Compressor Aquarium PVC Tube Valves Figure 1 Carbon dioxide collection system Figure 2 Filter locations in the poultry house 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 1 2 3 5 4
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Transcript of Electricity failure
Electricity failure is a major threat facing poultryproducers. It may be a rare occurrence incountries with a good power supply system but
it is a real and frequent problem in some areas. As aresult, back-up electricity generators are in use onalmost all farms around the world. Nevertheless,sometimes the unexpected happens - the back-upsystem also fails and disaster looms.
A few years ago, a study was conducted on aresearch farm to examine the effects of an electricityfailure on growing caged birds (hens) in winter whenthe outside temperature was below zero. Which birdswere the first to be affected? What was the cause ofdeath - carbon dioxide or ammonia build-up orexcessive temperatures? It had been general practicein that region to maintain the temperature in thehouse by turning off the ventilation system andsealing any cracks in the building.
TTrriiaall sseett--uupp
To measure the carbon dioxide concentration inthe poultry house, a gas collection system was fittedinto poultry house, as shown in Figure 1. Five sets offilters were placed in different locations and at
different heights on the cages and exhaust fan (Figure2). Each filter was connected to a PVC tube, whichwas in turn connected to a main panel with valves.Each valve controlled one filter. All five tubes led tothe service room of the poultry house. A vacuumcompressor was connected to the main valve panelthrough a fin filter. The compressor pumped the air toan aquarium, which was upside-down and sampleswere taken from another tube placed on the base ofaquarium.
There was a further filter outside the poultry houseto flush the system with fresh air after each sampling.The samples were analysed chemically, using acommercial colorimeter and carbon dioxide tubemodel 126SA with a range of 0.1-2.6%. Measurementswith low readings were repeated and the averagevalue was used.
HHooww ddoo bbiirrddss rreeaacctt ttoo aa ppoowweerr ffaaiilluurree??
After an electricity failure, the birds will initiallybreathe normally. When the oxygen concentration inthe air begins to fall, they start to breathe morerapidly for two reasons: firstly, the temperature in thehouse increases because of the birds’ body heat and
28 POULTRY INTERNATIONAL SEPTEMBER 2002
Electricity failure –limiting the damageElectricity failure –limiting the damage
A power cut shuts down the ventilation system, leading to a build-up of carbondioxide and rising temperature, often with dire consequences for the birds.Regular checking and maintenance of the back-up electricity generator isessential. The author has invented a system to keep the birds more comfortableuntil the power supply is re-established. —Dr Dhia Alchalabi
Filter
Filter
Compressor
Aquarium
PVC Tube
Valves
Figure 1 Carbon dioxide collection system Figure 2 Filter locations in the poultry house
1
2
3
45
6
7
89
10
11
1213
14
15
16
12
3
5
4
30 POULTRY INTERNATIONAL SEPTEMBER 2002
Electricity failure
Figure 3
Figure 5 Figure 6
Figure 4
the lack of air movement and exchange and secondly,carbon dioxide causes an increase in breathing ratewhen it is present in high concentration. This resultsin a vicious circle as the birds breathe ever morequickly to get more oxygen but at the same time, thisraises the carbon dioxide concentration and thehouse temperature further. Without an emergencyventilation system, the conditions become lethal.
IInntteerreessttiinngg rreessuullttss
Figures 3 to 6 show the carbon dioxide andtemperature levels at the different locations in thepoultry house after all the fans have been switchedoff.
Figure 2 shows the results from location 2. As theelectricity fails, the carbon dioxide level is at anacceptable 0.21% but after just 40 minutes, it hasrisen to 0.90% in the danger zone and thetemperature is close to 29°C. The birds will be understress. After another 40 minutes, carbon dioxide hasreached a lethal level of 1.40% and the temperature isover 31°C as the birds are now breathing rapidly to getmore oxygen and get rid of body heat. The birds willbe restless and noisy. After a further 40 minutes, thetemperature and the carbon dioxide levels at thatlocation will be unbearable and the weaker birds willdie from the combined effects of heat and carbondioxide.
The picture is similar at locations 3 and 4 (Figures 4and 5) but with higher levels of carbon dioxide andtemperature. Location 5 (Figure 6) was a littledifferent because here, carbon dioxide andtemperature increased more rapidly. After just 30minutes, the level of carbon dioxide was already fourtimes greater than at location 2, and three timeshigher than location 3.
This indicates which birds suffer first in the housewith a power failure. In less than two hours underthese conditions, the birds will start to die, startingfrom the upper tiers because of the combination oftemperature, relative humidity and the build-up ofcarbon dioxide.
Although the carbon dioxide concentration almostdoubled in less than two hours, the ammonia levelhardly changed from the normal level of 20 ppm.
The trial was terminated at that stage to save thebirds. By using emergency fans, the temperature andcarbon dioxide level were back to recommendedlevels within 10 minutes.
MMiinniimmiissiinngg tthhee ddaammaaggee wwhheenn tthhee ppoowweerr ffaaiillss
The best method of prevention is regular checks onthe back-up generator. The system must be run for atleast 30 minutes, for example, each times the house isempty between batches. This ensures the system is in
Electricity failure
See us atEurotier 2002
Hall 17 Booth B36
good condition and can handle a long run. Keep asupply of spare parts, e.g. belts, filters, oil. Check thebattery charger and make sure that the batteries arealways fully charged. Clear and clean the electricitygenerator shed and do not store other items there.Follow local regulations on storing flammablematerials and fluids. The shed should have a goodwaterproof and well-insulated roof.
Failure of the power system may seem highlyunlikely where all systems are fully computerised andthere is high-tech equipment to run the varioussystems. However, this is does not apply in all casesand from my experience, accidents happen even onthe most sophisticated farms. Faults go unrecognisedduring regular maintenance and checks.
AAuuttoommaattiicc rrooooff ooppeenniinngg
One way to prevent disasters is with an automaticroof opener (ARO). One type has been invented by theauthor. It operates mechanically in case of electricityfailure. The idea is simple and practical. The AROworks by an electromagnetic field generated by astrong coil when the power supply is operating,
keeping the roof vent closed. When the electricityfails, a rod is released by the spring, allowing somenatural ventilation of the house. The operation of thisARO is shown in Figure 7.
Dr. Dhia Alchalabi, poultry environmentconsultant, New Zealand.
Further information on the ARO system is availablefrom the author
34 POULTRY INTERNATIONAL SEPTEMBER 2002
Electricity failure Rod
Spring
Coil
On
Off
Emergency Auto-roof openerOn
Emergency Auto-roof openerOff
Figure 7 Design of an automatic roof opener
Normal operation
See us at EuroTier 2002 Hall 26 Stand B14
