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Norms and certifications for wood pellets

DIN 51731

DIN 51731 for wood pellets and its criteria are no proper indicator for quality because important parameter such as abrasion are not defined. Furthermore, an independent examination of the manufacturing process does not exist.



ÖNorm 7135

This Austrian norm is far more restrictive concerning quality. Abrasion (criterion for hardness and stability of pellets) for example is tested by exposing pellets to a certain stress in a Lignotester. Subsequently the resulting dust is measured and noted down in percentage. The less the figure of abrasion, the more solid are the pellets and that means less dust during the process of blowing them into the bunker.

Certification programmes according to

With certification according to DINplus the norms mentioned above are combined. The criteria that are stricter are laid down as parameter. The procedure of certification is conducted by members of an inspection institute according to DIN Certco standards at the plant. Controls take place regularly to ensure high quality at all times.

GGuaranty seal of the Pellet Association Germany (PVD)
The PVD has developed a guaranty seal, whose criteria are comparable to those of DINplus.

The following table shows a comparison between the criteria for Önorm M7135, DIN 51731 and DINplus.


Wood pellets quality norms
ÖNorm M 7135
DIN 51731
DIN plus
4 to 10 mm
4 to 10 mm
5 x D¹ < 50 5 x D¹
> 1,12 1,0 < Dichte< 1,4 > 1,12
< 10 < 12 < 10
< 0,50 < 1,50 < 0,50
Heating value
> 18 17,5 < HW< 19,5 > 18
< 0,04 < 0,08 < 0,04
< 0,3 < 0,3 < 0,3
< 0,02 < 0,03 < 0,02
< 2,3 - < 2,3
Press aid
< 2 ( ² < 2
no more than 20% of the pellets may be longer than 7.5 x Diametre
DIN prohibits additional matter. This prohibition however, is not valid for small heating systems


ÖNorm 7136 transport and storage of pellets

The criteria of DIN, Önorm and DINplus apply to production and the condition of pellets until they are loaded.
The transport of pellets is regulated by Önorm 7136. Considerable damage can arise from unprofessional transport or storage.
High demands are made on bunker, transport-vehicle and supplier. Criteria are for instance calibrated on-board scales, protection against humidity and suction devices.
The norm is aiming at establishing professional handling of pellets during the whole chain of transport.

© Holz-Energie-Zentrum Olsberg GmbH, 59939 Olsberg, Deutschland, 2006. All rights reserved.