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Negative pressure ventilation is the most popular method for ventilating poultry farms in cold weather due to its simplicity and relatively low initial costs.
Exhaust fans create negative pressure inside the house and give the poultry producer precise control over the amount of fresh air entering the house.
The air inlets distribute the cold outside air, sucked in by the exhaust fans, evenly throughout the house and direct it along the ceiling, where the warm air (produced by the birds and the heating system) accumulates near the ceiling; so that the fresh air will be heated before it descends to the level of the birds.
It doesn’t matter if the house is 30 or 200 meters long; it doesn’t matter if the house is 9 or 18 meters wide; it doesn’t matter if the house has broilers, layers, breeders or ducks.
With adequate air inlets and the right level of negative pressure, it is relatively simple to provide fresh, warm air to all birds in a house with minimal cost and effort.
If the cold, heavy air entering through the hatches of a house does not enter with sufficient velocity, it will tend to fall rapidly to the floor as it enters the house, causing the chicks to cool and the litter to clump.
NEGATIVE PRESSURE VENTILATION
One of the most important features of negative pressure ventilation is that it gives the poultry producer control over the rate at which clean, cool outside air enters the house.
The goal during cold weather is to maximize the distance the incoming cool air travels along the ceiling before descending to bird level.
The faster the air enters the house, the longer it will stay near the ceiling, the more it will mix with the warm air that accumulates near the ceiling and the less likely it is to cool the birds as it descends to the floor.
In addition, as the temperature of the incoming air increases, its ability to retain moisture increases, making it more effective at removing moisture from the bedding.
NEGATIVE PRESSURE VENTILATIONS AND DEPRESSION
In negative pressure ventilation, the depression determines the velocity of air entry through the house’s air inlets.
The greater the depression, the faster the air will enter the house.
The lower the depression, the slower the air enters the house.
The relationship between depression and air inlet velocity is very well defined.
In fact, the depression of the house can ...
