How to design the ventilation system of the pig house reasonably?
We know that for pig farms, maintaining good ventilation in the pig house has a great impact on the growth and development of pigs. Reasonable ventilation conditions can not only maintain a good temperature and humidity balance in the pig house, but also discharge harmful gases such as ammonia in the house in time, reducing the incidence of respiratory diseases in the pig herd. Therefore, a reasonable design of the ventilation system of the pig house is very important for the construction of the pig farm. So, how to design the ventilation system of the pig house to be more reasonable? Before understanding the design of the ventilation system, let us first understand what factors may affect the design of the ventilation system?
1. Factors affecting the design of ventilation system
The main factors that affect the design of the ventilation system are temperature, humidity, uniformity of temperature throughout the year, wind speed blowing through the pig, the amount of suspended dust and pathogens, the concentration of ammonia and toxic gases, etc.
(1) Temperature and humidity balance
Compared with the previous breeds, the current pig breeds have much higher heat production. Therefore, there is basically no need to increase the temperature artificially in the growing and finishing barn. There are two main purposes for ventilating the pig house in winter. One is to allow fresh air to enter the house; the other is to reduce the humidity in the house to prevent pathogenic microorganisms from breeding. In addition, the amount of ventilation that should be achieved for pigs at different stages of production is different in different seasons. The pig house should not be built too high, so as not to reach the proper ventilation rate in summer; the general pig house only lists the minimum and maximum ventilation rate, but in actual production, it cannot be directly changed from low to high. There must be a transition. Therefore, it is best to have large, medium and small fans in the pig house.
(2) Toxic and harmful gas
The accumulation of toxic and harmful gases (mainly ammonia, carbon monoxide, methane, hydrogen sulfide, etc.) in the pig house is a problem that requires great attention. In the pig house where manure is stored, the process of extracting pig manure, especially When there is agitation, there must be adequate ventilation, otherwise these harmful gases will be fatal to people and pigs.
2. Type of ventilation system-negative pressure ventilation system
Negative pressure ventilation is a ventilation mode in which indoor air is forced out by an exhaust fan in a relatively sealed space to form an instantaneous negative pressure, and outdoor air automatically flows into the room through the air inlet under atmospheric pressure. The whole system includes: exhaust fan, air inlet, controller, heater (winter), evaporative cooling device (summer), etc.
(1) Air inlet
①Requirements: to make the air evenly distributed: the size should be able to meet the maximum ventilation needs, should be able to be adjusted appropriately, and the ceiling should have enough space to install the air inlet.
②Arrangement: The arrangement of air inlets determines the distribution of air. Only good air distribution can eliminate dead corners and limit harmful wind; use different air inlets in winter and summer to make the air flow to the pig’s butt or head unit.
(2) Exhaust fan
Choose different models and sizes of fans for cold, mild and hot seasons.
①Installation requirements: The distance between each fan installation should not exceed the recommended maximum distance value; it should be along the center of the pig house: avoid corners; it should be convenient for wiring and maintenance.
②Factors that should be considered when choosing: air flow, fan surface shape, power, noise, quality, after-sales service, and price.
③Control of noise. Avoid speed close to 3500 r/min, because the fan will produce a lot of noise. Therefore, the direct motor-driven fan should be lower than 1800 r/min, and the belt-driven fan generally rotates around 500 r/min, the fan will be relatively quiet.
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