ISO 20904:2020

INTERNATIONAL ISO
STANDARD 20904
Second edition
2020-02
Hard coal — Sampling of slurries
Houille — Échantillonnage des schlamms
Reference number
©
ISO 2020
© ISO 2020
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Published in Switzerland
ii © ISO 2020 – All rights reserved

Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principles of sampling slurries . 2
4.1 General . 2
4.2 Sampling errors . 3
4.2.1 General. 3
4.2.2 Preparation error . 4
4.2.3 Delimitation and extraction errors . 4
4.2.4 Weighting error, E . 5
W
4.2.5 Periodic quality fluctuation error, E . 6
Q3
4.3 Sampling and overall variance . 6
4.3.1 Sampling variance. 6
4.3.2 Overall variance . 6
5 Sampling schemes . 7
6 Minimization of bias and unbiased increment mass .13
6.1 Minimizing bias .13
6.2 Volume of increment for falling stream samplers to avoid bias .14
6.3 Volume of increment for manual sampling to avoid bias .14
7 Precision of sampling and determination of increment variance .15
7.1 Overall precision .15
7.2 Primary increment variance .15
7.3 Preparation and testing variance .16
8 Number of sub-lots and number of increments per sub-lot .16
9 Minimum mass of solids in lot and sub-lot samples .17
9.1 General .17
9.2 Minimum mass of solids in lot samples .17
9.3 Minimum mass of solids in sub-lot samples .17
9.4 Minimum mass of solids in lot and sub-lot samples after size reduction .17
10 Time-basis sampling .18
10.1 General .18
10.2 Sampling interval .18
10.3 Cutters .18
10.4 Taking of increments .18
10.5 Constitution of lot or sub-lot samples .19
10.6 Division of increments and sub-lot samples .19
10.7 Division of lot samples .19
10.8 Number of cuts for division .19
11 Stratified random sampling within fixed time intervals.19
12 Mechanical sampling from moving streams .20
12.1 General .20
12.2 Design of the sampling system .20
12.2.1 Safety of operators .20
12.2.2 Location of sample cutters .20
12.2.3 Provision for duplicate sampling .20
12.2.4 System for checking the precision and bias.20
12.2.5 Minimizing bias .21
12.3 Slurry sample cutters .22
12.3.1 General.22
12.3.2 Falling-stream cutters .22
12.3.3 Cutter velocities .22
12.4 Mass of solids in increments .22
12.5 Number of primary increments .23
12.6 Routine checking .23
13 Manual sampling from moving streams .23
13.1 General .23
13.2 Choosing the sampling location .23
13.3 Sampling implements .24
13.4 Mass of solids in increments .24
13.5 Number of primary increments .24
13.6 Sampling procedures .24
14 Sampling of stationary slurries .25
15 Sample preparation procedures .25
15.1 General .25
15.2 Reduction mills .25
15.3 Sample division.25
15.4 Chemical analysis samples . .25
15.5 Physical test samples .25
16 Packing and marking of samples .26
Annex A (informative) Examples of correct slurry devices .27
Annex B (informative) Examples of incorrect slurry sampling devices .30
Annex C (normative) Manual sampling implements .34
Bibliography .35
iv © ISO 2020 – All rights reserved

Foreword
ISO (the International Organization for Standard
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