The essential operating data of spray nozzles is
Flow rates and spray angles are dependent on feed pressure and viscosity of the liquid to be sprayed. We have measured the flow rates stated in the catalogue with painstaking accuracy, using inductive flow meters.
The spray angle is determined right at the nozzle’s orifice. The indications given on spray widths and coverage diameters are more useful at larger distances from the orifice. Air friction losses and ballistic phenomenons influence the spray behavior and the size of the impact area in dependence on the chosen service pressure.
The pressure (p) is the feed pressure above atmospheric, which is available at the liquid inlet into the nozzle. The spraying operation is performed under counterpressure, the flow rate is dependent on the differential pressure. Minimum and maximum pressures are adjusted to the required flow rates and the spray quality.
Droplet sizes and droplet distribution
The droplet distribution of a nozzle must be known for many applications. The Laser Doppler Particle Analyzer has proved to be one of the most precise measuring devices for this purpose.
This method allows to measure simultaneously droplet sizes and droplet speeds. A full description of the spray characteristics can be obtained as a result.
Considering that the various spray patterns do not necessarily disintegrate into uniformly sized droplets, we use the Sauter diameter d32 to document the droplet size distribution.
Starting from this parameter, primarily used in process engineering, other droplet size definitions can be deduced, such as the arithmetic mean diameter d10, the mean volume diameter MVD, the logarithmic deviation LS. In the same way, other measured values may be processed to compile a full description of a measured droplet distribution.