ISO 21945:2020 pdf free.Solid biofuels一Simplified sampling method for small scale appl ications.
5 Principle
The main principle of sampling is to obtain (a) representative sample(s) from the whole lot concerned. Every particle in the lot or sub-lot to be represented by the sample should have an equal probability of being included in the sample. In order to do so a sampling plan is needed. Figure 1 shows the main steps of a sampling procedure.
Under certain circumstances (e.g. certain construction types of built in storages, silos or containers) representative sampling might not be possible.
6 Visual inspection
Visual inspection shall be used for the choice or verification of the classification of the solid biofuels. Based on the sampling plan, verification or selection of the sampling equipment and the sampling method shall also be made by visual inspection. If the lot/sub-lot consists of substantially inhomogeneous material or if it contains impurities (such as soil or pieces of metal) this shall be stated in the sampling report. If the biofuel type or the quality of it is diverging strongly from the one expected, the sampler shall report without any delay to the appropriate party for further instructions.
If the particle size distribution should be analysed the visible surface of the complete lot should be inspected for the longest particle — in addition to the sampling and testing — and its length shall be noted in the sampling report.
NOTE 1 It is advisable to take photographs of deviations noted during visual inspection.
NOTE 2 For documentation of oversized particles photographs are useful. Therefore, it is advisable to include a folding rule or any other scale into the photograph to enable the estimation of the particles size.
8 Methods for sampling
8.1 General
It is difficult to take samples in a way that satisfies the principle of correct sampling, stating that all individual parts of the lot shall have an equal probability of becoming part of the final sample. The chance that this can be achieved when the material is stationary (for example in a silo, or stockpile, or in a lorry) is low. It is easier when the material is moving (for example, on a conveyor belt, or being loaded into or unloaded from transport equipment). Hence sampling from moving materials is to be preferred wherever possible, care shall be taken that fuel parameters (physical properties) to be analysed are not affected.
The following general aspects of sampling shall be considered:
a) Sampling equipment shall be properly cleaned and maintained. The equipment shall be controlled after every sampling to avoid contamination of following samples.
b) The integrity of the sampled material shall be ensured, e.g. avoiding loss or gain of moisture, formation of fines etc. E.g. working quickly and storing the sample in an airtight container, e.g. plastic bag or bucket during sampling could help avoiding loss or gain of moisture.
c) All increments belonging to one combined sample shall be:
1) extracted in a uniform way,
2) of equal weight or volume,
3) transferred to the sampling bucket without any contamination or loss of material.ISO 21945 pdf download.