This Technical Specification specifies a method for the determination of particle density of irregularly shaped pieces of compressed fuels such as pellets or briquettes. It is not applicable to soft or semi-soft pellets. NOTE 1 The term soft pellet is defined in CEN/TS 15639. NOTE 2 Particle density is subject to variation due to the susceptibility of organic material to environmental or technical impacts such as air humidity, vibration, abrasion or biodegradation. Therefore, particle density can vary during time thus the measured values should be regarded as a momentary fuel property. NOTE 3 At the time of preparing this document, the production of briquettes of solid recovered fuels could not be identified in the European market.