scope:

This DIN SPEC describes a process for the characterization of atomized coating materials, like paint sprays or, more specifically, drops or wetted particles forming a paint spray. For this purpose, guidelines for the size measurement of spherical drops or nearly spherical drops have been defined. In such cases, the drop size is solely defined by the diameter. This DIN SPEC includes requirements about the necessary spatial resolution of the employed technique. Furthermore, guidelines for the acquisition of drop velocities and the related mass flux densities are provided. Beyond that, recommendations for the acceptable uncertainty of the measurement results are given.

This DIN SPEC is valid for applications, where the drop diameters are in the range of approximately 5 μm to 500 μm. In order to cover the most common paint spray applications, spray processes in explosive atmospheres, with high voltage applications and PWIS-free (free of paint-wetting impairment substances) are included.

Guidelines have been defined for the detection of outliers, i.e. drops whose diameters or velocities strongly deviate from mean or characteristic values of the overall spray.

NOTE An interesting value for the coating user is the transfer efficiency (compare DIN EN 13966-1). To determine this value, normally it is necessary to measure the coating process in the presence of the substrate. This DIN SPEC focuses on the characterization of the atomized material without a substrate. With the knowledge of the pure atomization process (local volume flux measurement compare DIN SPEC 91342) it is possible to deduce features of the coated surface (spray pattern on the substrate), for example by using numerical simulations. Therefore, the focus of the present DIN SPEC is on the atomized spray propagating unhindered by a substrate.