General purpose nozzles
A spray nozzle is a device which makes use of the pressure energy of a liquid to increase its speed through an orifice and break it into drops.
Its performances can be identified and described precisely, so that the design engineer can specify exactly the spray nozzle required for a given process.
The relevant characteristics which identify the performances of a nozzle are the following:
– The liquid flow delivered as a function of the nozzle feed pressure.
– The opening angle of the produced spray.
– The nozzle efficiency, as the ratio between the energy of the spray and the energy used by the nozzle.
– The evenness of the flow distribution over the target.
– The droplet size distribution of the spray.
Flat Fan Nozzles
In a flat jet spray the liquid droplets are sprayed in the shape of a flat liquid layer, with different thickness according to the principle used to generate the spray. A flat jet spray nozzle serves the purpose of spraying onto a surface or an object moving in a transverse direction with respect to the one of the jet surface, a typical example being the nozzles in a car washing tunnel. The vast majority of flat spray nozzles used in the industry work according to one of the following principles.
Full Cone Nozzles
In a full cone spray the droplets are distributed into a volume which is limited by a cone, having its origin point at the nozzle orifice. Such spray pattern is commonly used in a large variety of industrial processes, since it is the one which allows to distribute in an even way the water flow onto a surface: the full cone spray pattern is therefore useful, as a typical example, to evenly spray cooling liquid on a still surface. Another typical use is to distribute liquid droplets within a certain volume, like for example evenly distributing water droplets in he inside volume of a cooling tower. Because of the wide number of processes performed by means of full cone nozzles the original shape has evolved into a range of specialised types, where the full cone spray pattern, or a pattern similar to a full cone one, is obtained by different techniques.
Hollow Cone Nozzles
A hollow cone spray pattern consists of droplets concentrated onto the outer surface of a conical shape volume, with no droplets contained in the inside of the conical jet shape. These nozzles are normally used for smoke washing or gas cooling applications in several industrial processes.
Straight Jet Nozzles
This is the general purpose flat jet nozzle, where the liquid enters the nozzle in line with the axis length and is fed to a pressure chamber, from where it is ejected through the nozzle orifice. Flow value and spray angle are determined respectively from the orifice cross section and the orifice edge profile.
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