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The nozzle is the final component of the system and through which the water passes to be broken up into droplets according to its interior design, orifice and water pressure. As such it determines flow rate, droplet size and droplet size distribution. These characteristics, as well as material technology and the arrangement (size, density and spacing) of nozzles in the overhead system or on the cool pad, determine its success or failure in reducing house temperature to acceptable levels.
Installation of misting/fogging nozzles offers poultry producers the opportunity for application within a wide pressure range of 3 to 14 bar (40 to 200 psi) and fine droplets of less than 50 µm, which are considered optimum for rapid evaporation and effective cooling.
Misting and fogging nozzles may be installed in traditional overhead atomiser (nozzle) arrangements using PVC pipe and solvent-welded fittings with 3 m between each atomiser line, 2.5 to 3.0 m between atomisers in the line and a separation distance of 3 m between atomisers and the house eaves (roof rafters or struts).
Nozzle tips are most effective when used as the atomising element in a cool pad/tunnel air system for poultry house cooling. Banks of fogging nozzles are installed so that they are deployed 450 to 600 millimetres (mm) away from the pads, with spray directed at the pads so that they are permanently and uniformly wetted for maximum performance and long life.
Pad designers recommend fogging nozzles with a flow rate of 3.8 litres per hour and a spray angle of at least 80 degrees. A pad of 1.8 m in height should be provided with three rows of fogging nozzles on pipes 450 mm apart with a separation distance of 450 mm between individual nozzles along each pipe.
Several factors including the thickness of the pads used will determine cooling efficiency level obtained. A carefully worked out nozzle arrangement so that there are no dry spots on the pad, as well as regular cleaning and flushing of the pads to avoid plugging (blockage), is vital. Low-level siting of cool pads means that the nozzles are easy to clean and change.
Dr Terry Mabbett
Take the heat out of poultry house and off your flock
Birds do not possess sweat glands but instead lose water by evaporation from facial appendages and through panting. (Image source: Stephen Luke/Flickr)
