Conventional Air Atomising Nozzles
Classic atomisers are devices producing an atomized spray with the assistance of compressed air, where the liquid is broken into droplets when its outer surface is subjected to shear action from the high speed air flow. By assembling together a range of standard components in different materials, several different capacity values, spray patterns, spray angles and operation modes can be obtained. In addition, specific application problems can be addressed by the use of special accessories available on request.
The set-up is the device where air and liquid flow come in contact and produce the atomised jet. It consists of a liquid nozzle and an air nozzle, whose orifice dimensions are combined in several different ways in order to obtain the capacity, the spray pattern and the spray angle required.
The above spray parameters are given in the performance tables, beside each set-up code on the Conventional Air Atomising Spray Nozzle Data Sheet.
The atomiser body serves the purpose of conveniently connecting the set-up to the feed lines for air and water, and it may include some options like shut-off or orifice cleaning needles.
In addition to the MW type, the standard body, a more complete MX type includes an air operated cylinder for remote control of spray operation.
Accessories and Options
In addition to the standard range of components some specific requirements like resistance to internal erosion or solid build-up from water borne foreign matters, body options with a different design or different spray control procedures, can be addressed with special parts.
An atomising system is often used to control the humidity value in a confined room, like a wine cellar, or to spray some special products in the ambient atmosphere for different purposes.
In addition to our range of high quality atomisers we can supply regulation cabinets and spray control panels which allow to assemble of a professional and highly efficient atomising system.
A spray set-up is made out of a liquid nozzle and an air nozzle. When assembled the air nozzle fits precisely onto the liquid nozzle and the combination of the two provides the correct inside geometry to produce the spray.
Such parameters of the two parts like the number, dimensions and profile of their inside passages determines all the characteristics of the atomised spray produced by that given set-up.
A set-up can be selected according to the choices below.
The capacity tables in the following catalogue pages show the specification of each individual set-up, that is air and liquid capacities as a function of air and liquid feed pressures, and spray dimensions.
Spray dimensions are understood measured in still air for several pressure values, and cannot be precisely defined, therefore we give indicative values of the maximum throw and of the distance for which the spray maintains a consistent shape.
The set-up code, complete with the material code, can be used to order air and liquid nozzle together. Under the set-up code, air (An) and liquid nozzle (Ln) codes are shown separately for ordering them as spare parts, while Teflon seal and locknut can be ordered with the codes shown on the Conventional Air Atomising Spray Nozzle Data Sheet.
All PNR components are made interchangeable and can be combined even if made in different materials, like for example assembling an erosion resistant set-up in stainless steel with a brass body.
Complete Atomiser Code
Once the set-up code (and therefore the spray characteristics, has been choosen) it is necessary to choose the body and the options required to come to the complete atomiser code. A set-up can be assembled basically on two different body types:
Air Actuated Body
This body serves the only purpose of connecting the set-up inlets to the air and liquid feed lines. The plug an the body top can be replaced by several option equipment as shown on next page.
This body has a built in air cylinder allowing to start and stop the spray from a remote location. Additional options are shown at page 10 and 21.
An atomiser can work on two different liquid feed principles, that is:
• Liquid is supplied to the atomiser through a line under pressure
• Liquid is aspirated by the atomiser from a container at ambient pressure
It is the most widely used, and therefore a large range of capacities and spray patterns are available. Liquid capacity, air capacity and droplet sizes can be adjusted by regulating the air and liquid feed pressures and the two fluids are mixed inside the atomiser prior to be ejected.
(Internal mix atomisers). A different type allows for mixing the fluids just after they are ejected from the orifice, avoiding mutual influence of the two fluid pressure values inside a mixing chamber and allowing wider regulation range. (External mix atomisers).
These atomisers offer lower capacity values for liquids and a simpler layout since the liquid is aspirated from the atomiser through a Venturi effect. The liquid is simply supplied from an open container, whose level can be lower or higher than the atomiser one to fine tune the liquid capacity.
The atomising air provides the vacuum necessary into the mixing chamber for the Venturi effect.
The set-up can be designed in two different ways so as to obtain the following actions:
• Air and liquid are mixed up in a mixing chamber inside the atomiser and then they are ejected through the orifice as a spray.
• Air and liquid are ejected from the atomiser through different orifices, and the spray is generated by the impact of the two jets.
Internal Mix Set-ups
The spray is ejected from one or more orifices in the wall of a mixing chamber. In these atomisers a change in the pressure of one of the fluids inside the mixing chamber has an influence on the capacity of the second fluid and this effect reduces the ease of regulation.
As an example, increasing the air pressure will decrease the liquid quantity being atomised and the droplet size, and vice-versa.
External Mix Set-ups
The two fluids are ejected trough different orifices, their mixing LIQUID happens outside the orifice. Therefore their pressure values can be adjusted avoiding cross influence with a more precise and stabile regulation. External mix set-ups can only work with liquid feed under pressure, and only produce flat jet sprays.