5.1. Size of Droplets:-The size of the droplets produced by the Atomiser depends mainly on: rotation speed, flow rate, liquid surface tension. When supplied with pure water at minimal input pressure, an Atomiser with standard Feed Tube has a flow rate of about 5 litres/hour, and on 24 VDC runs at about 30,000 rpm, giving an average droplet diameter of 40 m m.

The higher the speed, the smaller the droplet size.
The maximum speed is obtained with 25 volts input; above this speed droplet size would not reduce much anyway. If the dc voltage to the Atomiser is reduced, the speed is reduced and larger droplets are obtained. The lowest speed is obtained with 10 volts input, where the relatively large, but consistently sized droplets are useful in some coating applications. Note that the Atomiser's speed is affected slightly by the flow rate - the higher the flow rate, the lower the speed.

The lower the flow rate, the smaller the droplet size.
Flow rate can be reduced and hence droplet size reduced by restricting the input flow. A Flow Controller is available from Newland Design, which incorporates a needle valve, as well as a indication of flow rate (with aqueous liquids only).Flow rate can be increased by increasing the pressure on the input, but flow rate must never exceed 25 litres/hour. Note, that flow rate also increases slightly with the speed of the Atomiser, due to suction generated by the unit.

The lower the surface tension, the smaller the droplet size.
Surface tension has a large effect on atomisation, because it represents the energy needed to break the liquid up into droplets. Note that surface tension is not the same as viscosity, and some viscous liquids (including most oils) have much lower surface tensions than water and can be handled veryeffectively by the unit. Pure water has a high surface tension, and a tiny amount of surfactant (eg. detergent) dissolved in it will reduce it significantly, so improving atomisation.

5.2. Size of Spray Cloud:-The size of the spray cloud produced by the Atomiser depends mainly on: liquid flow rate, rotation speed, liquid surface tension, and air conditions, such as air velocity and humidity &c.. When supplied with water at about 5 litres/hour, an Atomiser running at full speed produces in still air, an average spray cloud diameter of about 1 metre.

The higher the flow rate, the larger the spray cloud. The higher the rotation speed, the larger the spray cloud. At low flow rates and high speeds, the droplet size is too small and the spray too diffuse for a spray cloud to be defined. At high flow rates and low speeds the spray cloud takes a parabolic shape, with the droplets falling like drizzle, useful in some coating applications.

The low-momentum spray produced by the Atomiser and the small droplet size, mean that in some applications, forced air movement helps to improve spray dispersion or evaporation.

In humidification applications an air velocity of at least 1 metre/second is preferable, and at flow rates of up to about 10 litres/hour, an evaporation time of at least one second should be allowed for.

5.3. Alternative Spray Heads:- The standard Spray Head is of porous polypropylene. For certain applications Spray Heads of other materials may be fitted - porous polyethylene, porous PVDF, and porous stainless steel are available.

5.4. Running in:-The Atomiser has a running-in period from new, of about 100 hours - during which power consumption reduces, speed increases, and atomisation performance improves. Also, if a unit is left unused for some time, grease in the bearings will settle, giving rise to another brief running-in period when it is started again.