An objective reply is provided by the survey „Analysis of the grain size distribution of chips from Chippers of different brands acc. to. ÖNORM M 7122 and EN 14961-1”, prepared by the specific field “Nachhaltige Energie und Umwelttechnik NEU Tec“ (Sustainable energy and environmental technology NEU Tec) and the “3N-Kompetenzzentrum Niedersachsen Netzwerk Nachwachsende Rohstoffe e.V.” (3N Competence Center Lower Saxony Renewable Resources e.V.). Within the scope of this survey, chip samples from different chippers were taken at the occasion of the Fair „Bioenergy Decentral“ in Hanover on November 19, 2010.

The base material for all machines were equal, further details of the machines are described in detail in the analysis. The sampling was effected quite in a complex way according to the valid standards. Three sample baskets à 20 liters were filled. The screening was effected acc. to. ÖNORM M 7133 and DIN EN 1496-1. Each of the three baskets was screened three times after the two samples, in order to achieve a result which is as significant as possible. At the end of the survey the results of the individual machines were directly opposed to each other in a summary. For this purpose, corresponding mean values were created from the different tables.

The total results can be summarized in two central facts:

1. The JENZ machine produced the smallest amount of fine particles among the drum chippers in the evaluation according to ÖNORM as well as in the evaluation according to DIN EN 14961-1. Fine particles are chips smaller than 3.15 mm.

2. In the distribution of grain size up to 45 mm grain size there are no considerable differences between the examined machines.

2.Which conclusions are to be drawn from this analysis? In practice, it depends on the operator himself. He himself is responsible for the correct chip quality of his chipper by means of intensive and exact care and maintenance, sharp blades and counter-blades, the appropriate screening basket, the suitable discharge and the optimal adjustment. Finally, it can be concluded that the quality and goodness of chips depend on the actual composition and especially on the percentage of fine particles.