BS/EN 14243-3-2019 pdf download.Materials obtained from end of life tyres Part 3: Shreds, cuts and chips – Methods for determining their dimension(s) including protruding filaments dimensions.
a procedure as close as possible to probabilistic sampling in his judgement (i.e. judgemental sampling) and note the limitations in the sampling plan and sampling report.
To take samples in a way that Is truly representative of the material produced is easier when the material is moving (to be avoided for example in a stockpile, big bag or silo). Regarding shreds, it Is necessary to take samples when the material is in movement.
NOTE The determination of other properties than dimensions may result in different sampling requirements. This Is the case for the determination of physical properties (such as apparent density) or chemical composition.
5.2.2 Preparation of the sampling plan for determining dimensions
The first step is to identify the properties required in the testing programme and the lot in relation to which they are defined, for instance maximum projected length on a shreds production of 300 t”.
The lot size is based on production quality management decisions or specific customer requirements. The lot size may be defined by the producer as a fixed quantity produced between machine settings or a fixed quantity In a production day/shift/week or a fixed quantity. With regards to certain pieces exhibiting large dimensions, the tools for taking an increment shall be sufficiently large in order that the large pieces are equally sampled. For shreds, this typically results in Increments of more than 200 pieces (about 3 kg to 15 kg).
NOTE 1 Larger increments would slightly improve the sampling quality. while increasing the size of the field sample, therelore complicating the size reduction Into laboratory sample(s). It Is preferable to Increase the number of increments, thus increasing directly the representativeness.
For reference testing (contractual or pre-contractual) concerning shreds dimension(s) the field sample is a composite sample constituted of three increments taken at dates selected randomly along the period of time during which the lot is produced. When at one date there are no shreds at the sampling location, the increment is taken at another date preselected prior to sampling, unless this is caused by a major change in the production process (see below).
For routine testing concerning the dimension(s) of shreds the field sample consists of one increment taken at a date selected randomly along the period of time during which the lot is produced. When at this date there are no shreds at the sampling location, the increment Is taken at another date preselected prior to sampling, unless this is caused by a major change in the production process (see below).
During a sampling step the production process may be Interrupted by a major change. Such a major change would induce in the sample two different subpopulatlons, before and after the major change. Therefore, It is necessary to consider a lot before and a lot after the major change. Major changes may occur on the feed and on the production process.
NOTE 2 The random taking of three increments allows having a first approximation of the variability inside the considered lot. The random taking of one increment in routine testing allows also another evaluation of the variability when considering the lots obtained under comparable conditions.
5.3 Procedure for taking the field sample and producing the laboratory sample(s)
Taking increment(s) at the output of the conveyer in the falling zone. The used tool is typically a rectangular open scoop, i.e. without an edge on one of the long side capable of cutting” the entire flow. Such a scoop (see Auxjjx) shall have:
a) a width Lat least 1.5 times the width of the falling flow;
b) a depth P at least 2/3 of the width Land at least 2,5 times the higher dimension IIDF;
c) an edge height H equal at least to 1/3 of the width Land at least two times the higher dimension HDF. This scoop is moved for instance with a loader according to a detailed procedure adapted to the site condition. This scoop can be the bucket of a loader, provided that its cleanliness is compatible with the requirement of the dimension measurement, I.e. the absence of deposit. The taken increment is
considered as valid if both criteria are fulfilled:
— the increment consists of at least 200 pieces for shreds (after sieving of fines);
— the mass of the increment does not exceed 15 kg for shreds.
NOTE The minimum size of the increment Is specified as a minimum number of pieces In view of the statistical evaluation of the measurements of the maximum projected length of each piece. A specification In mass would result in significant differences depending on the size of the pieces.
For the determination of dimension(s), each increment constitutes a laboratory sample for such determination. If there are several increments, the dimension of each increment is determined and the average is calculated. This Is easier than reducing the size of the field sample prior to measurement of the dimension.BS/EN 14243-3-2019 pdf download.