The hatchery is where optimal conditions are created for life to develop, but while those conditions are meant for the development of chicken embryos, there are many other — unwanted — forms of life, like fungi and bacteria, that can also take advantage of these conditions in the hatchery, Maciej Kolanczyk, senior hatchery specialist with Royal Pas Reform, wrote in a white paper from the Pas Reform Academy.
That makes hygiene an important concern, he said, noting that it is relatively easy to create sanitary barriers on the floor of a hatchery, but air is a difficult carrier to control.
The air pressure system in the hatchery was originally created as a hygiene measure. Contamination in the hatchery progresses in tandem with the incubation process: setting = “clean,” and hatch = “dirty”. That makes the parts of the building easy to define. Air should move consistently in one direction: from “clean” to “dirty”. That is logical and may sound easy — but it is not, Kolanczyk said.
Forcing the air to go in one direction requires a system of devices that measure and control the air pressure so it goes from high in the “clean” part to lower in the “dirty” part. The hatchery building is a complex construction, with many obstacles and opportunities for leakages, Kolanczyk pointed out. Making the system work requires a certain amount of discipline so that the air is forced to move as planned. In addition, fresh air, preconditioned by air handling units, is a costly product and must be used economically.
The pressure differences are not only of hygienic value; the difference in air pressure between the incubator air inlet and the outlet supports the ventilation rate in the machine, Kolanczyk said. However, more does not necessarily mean better. The air supply must be balanced by adequate air exhaust.
A too-high pressure difference may create a shortcut in the air circuit. Air will take the easiest way from the inlet to the exhaust and leave dead spots elsewhere, causing poor uniformity of temperature and ventilation, Kolanczyk said.
The balance — an equilibrium between supply and removal — has a dynamic character. Demand for air exchange fluctuates depending on the phase of the incubation cycle and volume of the load. The hatchery’s air pressure control system must be reactive and flexible. The air supply demand for the entire installation also changes with the number of machines in use.
He noted that air pressure at supply and exhaust are relative values, and a reference — external air pressure — is used to measure them. External air pressure is measured by sensors located outdoors, where they are potentially exposed to the wind. It is essential to make sure this reference is reliable, so it is very important to ensure that the reference sensors are correctly located and protected.
Kolanczyk provided several points of advice:
- Make sure the airflow in the building is in line with the concept.
- Always keep all doors and windows closed.
- Control the status of fans used to maintain the pressure system in the building.
- Pay attention to the technical status of air handling units, controlling their filters, heating and cooling coils and motors.
- Maintain the incubator's inlet and exhaust pressures as recommended by the machine manufacturer.
- Make sure the incubators are well sealed and that no air escapes though the dampers of machines that are not in use.
- Install the reference pressure sensors so they are out of the direct influence of the wind.
- In case of doubt, check the distribution of eggshell temperatures in the incubators and the hatch in different parts of the hatcher. An increased spread may be an indication of an incorrect pressure ratio between inlet and exhaust.