Tiêu chuẩn iso 13909 2 2016

© ISO 2016 Hard coal and coke — Mechanical sampling — Part 2 Coal — Sampling from moving streams Houille et coke — Échantillonnage mécanique — Partie 2 Charbon — Échantillonnage en continu INTERNATION[.]

Hard c oal and c oke — Mechanical

Part 2:

Ho ille et coke — Éch ntillo n ge méca ique —

Partie 2: Ch rb n — Éch ntillo n ge en co tinu

S con edition

2 16-07-0

Refer ence n mb r

ISO 1 9 9-2:2 16(E)

COPYRIGHT PROTECTED DOCUMENT

© ISO 2016, P blshed in Sw itz rlan

A ll rig hts r eserved Unles otherw ise spe ified, nopar of this p blc tion ma y be r epr od c d or utilz d otherw ise in an form

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written permis ion Permis ion c n be req esed from either ISO at the ad r es below or ISO’s member bod y in the c u try of

F reword v

1 Sc ope 1

2 Nor mati ve r eferenc es 1

3 Terms an definitions 1

4 Establshing a sampl ng s heme 1

4.1 General 1

4.2 Desig n of the samplng scheme 2

4.2.1 Mate ial to be sampled 2

4.2.2 Division of lots 2

4.2.3 Basis of samplng 2

4.2.4 Pr ecision of sampl ng 2

4.2.5 Bias of samplng 3

4.3 Pr ecision of r esult 3

4.3.1 Pr ecision an total v rianc 3

4.3.2 Primary incr ement v rianc 4

4.3.3 Pr ep ration an testing v rianc 4

4.3.4 Numbe of sub-lots an n mbe of increment pe sub-lot 4

4.4 Minimum mas of sample 7

4.5 Mas of primary increment 9

4.6 Siz analysis 9

5 Metho s of samplng 10

5.1 General 1

5.2 Time-b sis samplng 1

5.2.1 Method of taking primary incr ement 1

5.2.2 Samplng inte v l 1

5.2.3 Mas of incr ement 1

5.3 Mas -b sis samplng 1

5.3.1 Method of taking primary incr ement 1

5.3.2 Samplng inte v l 1

5.3.3 Mas of incr ement 1

5.4 Stratified ran om sampl ng 1

5.4.1 General 1

5.4.2 Time-b sis s r atified random samplng 1

5.4.3 Mas -b sis stratified r an om samplng 1

5.5 Referenc samplng 1

6 Desig n of mechanical sampler .13

6.1 Safety 1

6.2 Information 1

6.3 Basic r eq ir ement 1

6.4 L cation of sampl ng eq ipment 14

6.5 Pr ovision for che king pr ecision 14

6.6 Pr ovision for tes ing for bias 14

6.7 General r eq ir ements for desig ning me hanical sample s 14

6.8 Desig n of fal ng -str eam-type sample s 14

6.8.1 General 14

6.8.2 Cute velocity

1 6.9 Cr os -belt-type primary sample s 1

6.9.1 Operation 1

6.9.2 Desig n of cr os -belt sample s 2

6.1 Maintenanc an che king of samplng eq ipment 2

7 Handlng and storag e of samples 22

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ISO cola orat es closely with the Int ernational Ele trot ech ical C mmis ion (IEC) on al matt ers of

ele trot ech ical s an ardization

The proc d r s used t o develo this document an those int en ed for it furthe maint enanc ar

desc ibed in the ISO/IEC Dir ctives, Part 1 In p rticular the dife ent a pro al c it eria ne ded for the

dife ent ty es of ISO document should be not ed This document was draft ed in ac ordanc with the

edit orial rules of the ISO/IEC Dir ctives, Part 2 ( e www.iso.org dir ctives)

A tt ention is drawn t o the p s ibi ity that some of the element of this document ma be the subje t of

p t ent right ISO shal not be held r sponsible for identifying any or al such p t ent right Detais of

any p t ent right identified d ring the develo ment of the document wi be in the Introd ction an / r

on the ISO ls of p t ent de larations r c ived ( e www.iso.org p t ent )

Any trade name used in this document is information given for the convenienc of use s an does not

cons itut e an en orsement

F or an ex lanation on the meaning of ISO spe if ic t erms an ex r s ions r lat ed t o conformity

as es ment, as wel as information a out ISO’ s adhe enc t o the WTO principles in the Te h ical

Bar ie s t o Trade (TBT), se thefolowing URL:F or word - Sup lementary information

The committ ee r sponsible for this document is ISO/TC 2 , S lid mine al f els , Subcommitt ee SC 4,

S mpln

This se on edition canc ls an r plac s the firs edition (ISO 1 9 9- 2:2 0 ), w hich has be n

t ech icaly r vised

ISO 1 9 9 consis s of the fol owing p rt , un e the g ene al title Hard c oal a d c oke — Mecha ic al

s ampln :

— Part 1: G ene al introduc tio

— Part 2 : Co l — S mpln from mov in s tr ams

— Part 3: Co l — S mpln froms tatio ar y lot

— Part 4: Co l — Prep ratio o tes t s amples

— Part 5: Coke — S mpln from mov in s tr ams

— Part 6 : Coke — Prep ratio o tes t s amples

— Part 7: Meth ds fr dete minin the pr c i s io o s ampln ,s ample pr p ratio a d tes tin

— Part 8: Meth ds o tes tin fr bias

An ex B forms a normative p rt of this p rt of ISO 1 9 9 An ex A of this part of ISO 1 9 9 is for

information only

Hard c oal and c oke — Mechanical sampling —

Part 2:

This part of ISO 1 9 9 spe ifies proc d r s an r q ir ment for the design an es a l shment

of me hanical sample s for the samplng of co l from mo ing s r ams an desc ibes the methods of

samplng used

It does not co e me hanical sampl ng from s ationary lot w hich is dealt with in ISO 1 9 9-3

[1]

2 Normati ve r eferences

The folowing document , in w hole or in p rt, ar normatively r fe enc d in this document an ar

in ispensa le for it a pl cation F or dat ed r fe enc s, only the edition cit ed a pl es F or u dat ed

r fe enc s, the lat es edition of the r fe enc d document ( inclu ing any amen ment )a pl es

ISO 1 9 9-1:2 1 , Hard c oal a d c oke — Mecha ic al s ampln — Part 1: G ene al introduc tio

ISO 1 9 9-4, Hard c oal a d c oke — Me h nic al s ampln — Part 4 : Co l — Prep ratio o tes t s amples

ISO 1 9 9-7, Hard c oal a d c oke — Mecha ic al s ampln — Part 7: Meth ds fr dete minin the pr c i s io

o s ampln ,s ample pr p ratio a d tes tin

ISO 1 9 9-8, Hard c oal a d c oke — Mecha ic al s ampln — Part 8: Meth ds o tes tin fr bias

ISO 2 3 8, Hard c oal a d c oke — Guida c e to the ins pec tio o mecha ic al s ampln sys tems

3 Terms and definitions

F or the purposes of this document, the t erms an def initions given in ISO 1 9 9-1a ply

4 Establ shing a sampl ng scheme

The g ene al proc d r for es a l shing a samplng scheme is as fol ow s

a) Define the q alty p ramet ers t o be det ermined an the ty es of samples r q ir d

b) Define the lot

c) Define or as ume the pr cision r q ir d ( e 4.3.1)

d) Det ermine the method of combining the inc ement int o samples and the method of sample

pr paration ( e ISO 1 9 9-4 )

e) Det ermine or as ume the v ria i ty of the co l ( e 4.3.2) an the v rianc of pr p ration an

t es ing ( e 4.3.3) Methods for det ermining v ria i ity an the v rianc of pr p ration an t es ing

ar given in ISO 1 90 -7

f) Es a lsh the n mbe of sub-lot an the n mbe of inc ement pe sub-lot r q ir d t o at ain the

desir d pr cision ( e 4.3.4)

g) De ide w hethe t o use time-b sis or mas -b sis samplng ( e Clause 5) and def ine the samplng

int erv ls in min t esfor time-basis samplng or in t on es for mas -b sis sampl ng

h) Asc rtain the nominal t op siz of co l for the purpose of det ermining the minimum mas of sample

( e 4.4 an Ta le 1)

NOTE T e nominal top size may initial y b as ertained by consulting the consignment details, or by visual

estimation, an may b verif ied, if neces ary, by preliminary test work

i) Det erminethe minimum a e ag e inc ement mas ( e 4.5)

4.2 Desig n of the sampl ng s heme

4.2.1 Mater ial to be sampled

The firs s ag e in the design of the scheme is t o identify the co l t o be sampled Samples ma be

r q ir d for t echnical ev luation, proc s control, q al ty control and for comme cial r asons b b th

the prod c r an the cust ome It is es ential t o asc rtain ex ctly at w hat s ag e in the co l-han lng

proc s the sample is r q ir d an , as far as practica le, t o design the scheme ac ordingly In some

ins anc s, howeve , it ma pro e impractica le t o o tain samples at the pr fe r d point an , in such

cases, a mor practica le alt ernative is r q ir d

4.2.2 Di visio of lots

A lot ma be sampled as a w hole or as a se ies of sub-lot , e.g co l dispat ched or delve ed o e a pe iod

of time, a ship lo d, a train lo d, a wag on lo d or co l prod c d in a c rtain pe iod, e.g a shif

It ma be ne es ary t o divide a lot int o a n mbe of sub-lot in orde t o impro e the pr cision ofthe

r sult F or lot sampled o e long pe iods, it ma be ex edient t o divide the lot int o a se ies of sub-lot ,

o taining a sample for each

4.2.3 Basis of sampl ng

Samplng ma be car ied out on eithe a time-b sis or a mas -b sis In time-b sis sampl ng, the samplng

int erv l is def ined in min t es an se onds an the inc ement mas is pro ortional t o the flow rat e at

the time of taking the inc ement In mas -b sis samplng, the samplng int erv l is def ined in t on es

an the mas of inc ement cons ituting the sample is u iform Of these two alt ernatives, time-b sis

samplng is easie t o implement an ve ify, be ause only a f ix ed spe d cutt er an a timing devic ar

r q ir d On the othe han , for mas -b sis sampl ng, a convey r belt weight omet er is r q ir d as wel

as a devic that is controled suff iciently t o adjus the primary cutt er spe d inc ement b inc ement t o

achieve uniform inc ement mas

4.2.4 Precisio of samplng

Aft er the desir d samplng pr cision has be n sele t ed, the n mbe of sub-lot an the minimum

n mbe of inc ement pe sub-lot cole t ed shal be det ermined as desc ibed in 4.3.4, an the a e ag e

mas of the primary inc ement shal be det ermined as desc ibed in 4.5

F or single lot , the q al ty v riation shal be as umed as the wors case ( e 4.3.2) The pr cision of

samplng achieved ma be measur d using the proc d r of r plcat e samplng ( e ISO 1 9 9-7)

A t the s art of r gular sampl ng of u k own co ls, the wors -case q alty v riation shal be as umed,

in ac ordanc with 4.3.2 When samplng is in o e ation, a che k ma be car ied out t o con rm that the

desir d pr cision has be n achieved, using the proc d r s desc ibed in ISO 1 9 9-7

If any subseq ent chang e in pr cision is r q ir d, the n mbe of sub-lot an ofinc ement shal be

chang ed as det ermined in 4.3.4 an the pr cision at ained shal be r che ked The pr cision shal also

be che ked if the e is any r ason t o sup ose that the v ria i ty of the co l being sampled has inc eased

The n mbe of inc ement det ermined in 4.3.4 a pl es t o the pr cision of the r sult w hen thesamplng

e rors ar larg e r lative t o thet es ing e rors, e.g for mois ur cont ent

4.2.5 Bias of samplng

It is of p rticular importanc in samplng t o ensur , as far as p s ible, that the p ramet er t o be measur d

is not alt er d b the sampl ng an sample pr p ration proc s or b subseq ent st orag e prior t o t es ing

This ma r q ir , in some cir ums anc s, a l mit on the minimum mas of primary inc ement se 4.5)

When cole ting samples for mois ur det ermination from lot o e an ext en ed pe iod, it ma be

ne es ary t o lmit the s an ing time of samples b dividing thelot int o a n mbe of sub-lot ( e 4.3.4)

Samplng sy st ems shal be t est ed for bias in ac ordanc with the methods given in ISO 1 9 9-8

4.3 Precision of r esults

4.3.1 Pr ecisio and total varianc e

In al methods of samplng, sample pr p ration and analy sis, e rors ar incur ed an the ex e imental

r sult o tained from such methods for any given paramet er wi l deviat e from the true v lue of that

p ramet er Whie the a solut e deviation of a single r sult rom the “ rue” v lue cannot be det ermined,

it is pos ible t o make an es imat e of the pr cision of the ex e imental r sult This is the closenes with

w hich the r sult of a se ies of measur ment made on the same co l a r e among themselves, and the

deviation of the mean of the r sult from an ac ept ed r fe enc v lue, i.e the bias of the r sult ( e

ISO 1 9 9-8)

It is p s ible t o design a sampl ng scheme b w hich, in principle, an arbitrary level of pr cision can be

achieved

The desir d o e al pr cision for a lot is normaly a r ed betwe n the p rties conc rned In the a senc

of such a r ement, a v lue of one t enth of the ash cont ent ma be as umed up t o 1 % ash, subje t t o a

ma imum of 1% a solut e for ash cont ent a o e1 %

The theory of the es imation of pr cision is discus ed in ISO 1 9 9-7 The folowing formula is de ived:

is thees imat ed in ex of o e al pr cision of samplng, sample pr p ration an t es ing for

the lot, ex r s ed as a pe c ntag e a solut e;

V

I

is theprimary inc ement v rianc ;

n is then mbe of inc ement pe sub-lot ;

m is then mbe of sub-lot in the lot ;

V

P

is thepr p ration an t es ing v rianc

If the q alty of a co l of a ty e not pr viously sampled is r q ir d, then in orde t o devise a samplng

scheme, as umptions ha e t o be made a out the v ria i ty ( e 4.3.2) The pr cision actual y achieved

for a p rticular lot b the scheme devised can be measur d b the proc d r s given in ISO 1 9 9-7

4.3.2 Pr imar y increment var ianc e

The primary inc ement v rianc , V

Idepen s up n the ty e an nominal t op siz of co l, the degr e

of pr -tr atment an mixing, the a solut e v lue of the p ramet er t o be det ermined an the mas of

inc ement taken

The n mbe of inc ement r q ir d for the g ene al-analy sis sample an the mois ur sample shal be

calculat ed separat ely using the r lev nt v lues of inc ement v rianc an the desir d pr cision If a

common sample is r q ir d, the n mbe of inc ement r q ir d for that sample shal be the gr at er of

the n mbe s calculat ed for the g ene al-analy sis sample an the mois ur sample r spe tively

NOTE For man co ls, the inc ement variance for ash is higher than that or moisture an hence, for the same

precision, the n mb r of inc ements req ired for the g eneral-analysis sample wil b adeq at e for the moisture

sample an for the common sample

The v lue of the primary inc ement v rianc , V

I

r q ir d for the calculation of the pr cision using

F ormula (1) can be o tained b eithe

a) dir ct determination on the co l to be sampled using one of the methods desc ibed in ISO 1 9 9-7, or

b) as uming a v luedet ermined for a simi ar co l from a simi ar co l han l ng an sampl ng sy st em

If neithe of these v lues is a ai a le, a v lue of V

I

= 5 for the ash cont ent of unwashed an blen ed co ls

I

= 3 for the ash cont ent of washed co ls can beas umed initial y an che ked, aft er thesamplng

has be n car ied out, using one of the methods desc ibed in ISO 1 9 9-7

4.3.3 Preparatio and testin var ianc e

The v lue of the pr p ration an t es ing v rianc , V

P, r q ir d for the calculation of the pr cision

using F rmula (1)can be o tained b eithe

a) dir ct determination on the co l to be sampled using one of the methods desc ibed in ISO 1 9 9-7, or

b) as uming a v luedet ermined for a simi ar co l from a simi ar sample pr p ration scheme

If neithe of these v lues is a ai a le, a v lue of 0,2 for ash cont ent can be as umed initialy an

che ked, aft er the pr p ration an t es ing has be n car ied out, using one of the methods desc ibed in

ISO 1 9 9-7

4.3.4 Number of sub-ots and numbe of incr ements per sub-ot

4.3.4.1 General

Then mbe of inc ement taken from a lot in orde t o achieve a p rticular pr cision is a function of the

v ria i ity of the q al ty of the co l in the lot, ir espe tive of the mas of the lot The lot ma be sampled

as a w hole, r sulting in one sample, or divided int o a n mbe of sub-lot r sulting in a sample from each

Such division ma bene es ary in orde t o achieve the r q ir d pr cision, an the ne es ary n mbe of

sub-lot shal be calculat ed using the proc d r given in 4.3.4.2

Anothe important r ason for dividing the lot is t o maintain the int egrity of the sample, i.e t o avoid

bias aft er taking the inc ement, p rticularly, in orde t o minimiz los of mois ur d e t o s an ing The

ne d t o do thisis dependent on fact ors such as the time taken t o cole t samples, ambient t empe atur

an h midity con itions, the ease of keeping the sample in sealed containe s d ring cole tion an the

particle siz of the co l It is r commen ed that, if mois ur los is suspe t ed, a bias t es be car ied

out t o comp r the q alty of a r fe enc sample immediat ely aft er extraction with the sample aft er

s an ing for the normal time If bias isfou d, the sample s an ing time should be r d c d b cole ting

samples mor fr q ently, i.e inc easing the n mbe of sub-lot

The ema be othe practical r asonsfor dividing the lot such as the folowing:

a) for convenienc w hen samplng o e a long pe iod;

b) t o keep sample mas es manag ea le.

The designe of a samplng scheme should cat er for the wors case anticip t ed an wi then t end t o

use a highe v lue for V

Ithan ma actual y oc ur w hen the syst em is in o e ation On implementing a

new sampl ng scheme, a che k on the actual pr cision being achieved should be car ied out using the

methods desc ibed in ISO 1 9 9-7 This ma indicat e that some chang es ar r q ir d t o achieve the

r q ir d pr cision, in which case, the n mbe of sub-lot an inc ement shal be r calculat ed using

the proc d r s given in 4.3.4.2

4.3.4.2 Calculatio of numbe of sub-ots and incr ements

The n mbe of sub-lot and n mbe of inc ement r q ir d pe sub-lot ar es a lshed using the

folowing proc d r

Det ermine the minimum n mbe of sub-lot r q ir d for practical r asons ( e 4.3.4.1)

Es imat e the n mbe of inc ement , n, in each sub-lot or a desir d pr cision from the folowing formula

[o tained b transp sing F ormula (1)]:

I

(2)

A v lue of inf inity or a neg tive n mbe in icat es that the e rors of pr p ration an t es ing ar such

that the r q ir d pr cision cannot be achieved with this n mbe of sub-lot In such cases, or if n is

impractica ly larg e, inc ease the n mbe of sub-lot b one of the folowing means

a) Cho se a n mbe cor esp n ing t o a convenient mas , r calculat e n from F ormula (2) an r peat

this proc s u ti n is a practica le n mbe

b) De ide on the ma imum practica le n mbe of inc ement pe sub-lot, n

1, an calculat e m from

A djus m upwards, if ne es ary, t o a convenient n mbe an r calculat e n

Take n as 1 if the final calculat ed v lue is les than 1

NOTE T e formula given in 4.3.4.2 wil g neral y estimat e a higher n mb r for the req ired n mb r of

inc ements This is b cause it is b sed on the as umption that the q ality of co l has no serial cor elation;

however, serial cor elation is always present o some de re In ad ition, b cause a certain amou t of preparation

an t esting is req ired when me suring the inc ement variance, the preparation an testing er or are inclu ed

more than once

Example 1

The lot is 2 00 t del ve ed in 5 0 0 t train lo ds an the r q ir d pr cision, P

L, is 0,2 % ash The

q alty v riation is k own and the folowing v lues ha e be n det ermined:

primary inc ement v rianc , V

a) Initial n mbe of sub-lot

It has be n de ided that the minimum n mbe of sub-lot shal be four The efor , take sub-lot of

500 t each ( i.e one sub-lot pe train lo d in this case)

b) Numbe of inc ement pe sub-lot

a) Initial n mbe of sub-lot

Take a dai y sample ( i.e m = 2 in orde t o avoid risk of bias b o e night t orag e of samples)

b) Numbe of inc ement pe sub-lot

a) Initial n mbe of sub-lot

Take an hourly sample, i.e m = 1

b) Numbe of inc ement pe sub-lot

k own an the folowing v lues ha ebe n det ermined:

primary inc ement v rianc , V

a) Numbe of sub-lot

The cust ome r q ir s a r sult b sed on at leas two samples

b) Numbe of inc ement pe sub-lot

This neg tive n mbe in icat es that the e rors of pr p ration and t es ing ar such that the r q ir d

pr cision cannot be achieved with this n mbe of sub-lot

It could be de ided that 5 inc ement is the ma imum practica le n mbe in a sub-lot an from

4.4 Minimum mas of sample

F or mos paramet ers, p rticularly siz analy sis an those that ar particle-siz r lat ed, the pr cision

of the r sult is lmit ed b the a i ty of the sample t o r pr sent al the p rticle siz s in the mas of co l

being sampled

The minimum mas of a sample is depen ent on the nominal t opsiz of the co l, the pr cision r q ir d

for the p ramet er conc rned an the r lationship of that p ramet er t o p rticle siz Some such

r lationship a ples at al s ag es of pr paration Theat ainment of this mas wi not, in it elf, guarant ee

the r q ir d pr cision, be a use pr cision isalso depen ent on the n mbe of inc ement in the sample

an their v ria i ty ( e 4.3.4)

Values for the minimum mas of samples for g ene al analy sis t o r d c the v rianc d e t o the

p rticulat e natur of the co l t o 0,0 , cor esp n ing t o a pr cision of 0,2 % with r g rd t o ash, ar

given in column 2 of Ta le 1 ( e R efe enc [3]) C lumn 3 of Ta le 1 gives the cor esp n ing minimum

mas es of divided samples for t otal mois ur analy sis, w hich ar a pro imat ely 2 % of the minimum

mas es for g ene al analy sis, subje t t o an a solut e minimum of 0,6 kg

Table 1 — Minimum mas of sample for g neral analysis and determination of total

Samples for det ermination

of t otal mois ur cont ent

NO E 1 The mas es for the general analysis an c mmon samples have be n determined to

red c the varianc d e to the par iculate nature of c al to 0,01, c r espon in to a pre ision

calculat ed from F ormula (4 )

is the r q ir d pr cision, with r g rd t o ash, d e t o the p rticulat e natur of the co l

When a co l is r gularly sampled un e the same cir ums anc s, the pr cision o tained for al the

r q ir d q alty paramet ers shal be che ked in ac ordanc with ISO 1 9 9-7 an the mas es ma be

adjust ed ac ordingly Howeve , the mas es shal not be r d c d below the minimum r q ir ment laid

down in the r lev nt analy sis s an ards

When pr paring co l t o prod c samples for multiple use, ac ount shal also be taken of the in ivid al

mas es an siz dis ribution of the t es samples r q ir d for each t es

4.5 Mas of primary increment

The mas , m

I

in ki o rams, of an inc ement taken b a me hanical cutt er with cut ing edg es normal t o

the s r am at the discharg e of a mo ing s r am can be calculat ed from F ormula (5)

m

Cb

vI

C is the flow rat e, in t on espe hour;

b is the cutt er a e tur width, in mi lmetr s;

NOTE T e cut er aperture value used for calculating the mas of an inc ement is the distance b tween the

le ding edg s of the cut er lips f ir t striking the stre m of the material

v

C

is the cut er spe d, in metres per secon (se 6.8.2)

F or a c os -belt sample , the mas , m

C is the flow rat e, in t on espe hour;

b is the cutt er a e tur width, in mi lmetr s;

v

B

is the belt pe d, in metr s pe se on

The minimum a e ag e mas of primary inc ement t o becole t ed, m

I'

, is calculat ed from F ormula (7)

is the minimum mas of sample( e Ta le 1);

n is the minimum n mbe of inc ement taken from the sub-lot ( e 4.3.4)

When measuring primary inc ement v rianc ( e ISO 1 9 9-7 :2 1 , Clause 6) at pr lminary s ag es in

the design of the sampl ng scheme, use inc ement mas es that ar close t o those ex e t ed t o be taken b

the sy st em Aft er implementation of the sampl ng scheme, the pr cision of the r sult can be es imat ed

an adjust ed ( e ISO 1 90 -7), b inc easing or de r asing the n mbe of inc ement in the sample,

keeping the same inc ement mas

4.6 Size anal ysis

W ithin thesco e of this p rt of ISO 1 9 9, the co ls t o besampled wi l exhibit larg e dife enc s in siz ,

siz rang e an siz dis ribution In ad ition, the p ramet ers t o be det ermined (pe c ntag e r tained on

a p rticular sieve, mean siz , et c ) ma dife from case t o case Furthe mor , w hen sample division is

a pled, division e rors shal be taken int o ac ou t, w he eas, they ar non-exist ent if sizing is pe formed

without any pr c ding division

Take these fact ors int o ac ou t w hen a plying thet echniq es for calculating n mbe s of inc ement for

a p rticular pr cision ( e 4.3.1 t o 4.3.4) In the a senc of any information on inc ement v rianc et c

initial y take 2 inc ement pe sample

The pr cision for the p rticular p ramet er r q ir d shal then be che ked an the n mbe of inc ement

adjust ed ac ording t o the proc d r desc ibed in ISO 1 9 9-7

Minimization of degradation of samples used for det ermination of siz dis ribution is vital t o r d c

bias in the measur d siz dis ribution To pr vent p rticle degradation, it is es ential t o ke p fr e-fal

dro st o a minimum Trial t es s should be made in ac ordanc with the method given in ISO 1 9 9-8 t o

det ermine the degr e of degradation

The minimum mas es of sample for siz analy sis ar given in Ta le 2 The mas es have be n calculat ed

on the b sis of the pr cision of the det ermination of o e siz , i.e the co l a o e the nominal t op siz

Pr cision for othe siz fractionswi l normal y be bett er than this

Table 2— Minimum mas of sample for size analy sis

Samplng shal be car ied out b sy st ematic samplng, eithe on a time-b sis or on a mas -b sis, or b

s ratified random samplng The proc d r s of sample pr p ration v ry in ac ordanc with the ty e of

samplng emplo ed ( e ISO 1 9 9-4 )

It is es ential that each inc ement taken from a s r am r pr sent the ful width an depth of the s r am

The consist ency of lo ding of the belt should be controled, as far as pos ible, so that sampl ng is as

efficient as p s ible The flow should be made r asona ly uniform o e the w hole c os -se tion of the

s r am at al times b means of controled lo ding or suita ledevic s such asfe d ho pe s, ploughs, et c

Whichever method of primary inc ement col e tion is used, it is es ential that the inc ement does

not complet ely f il or overflow the sampl ng devic W ith me haniz d sampl ng devic s, the primary

inc ement mas ma be conside a ly larg er than that ne es ary t o prod c the calculat ed minimum

sample mas Henc , a sy st em of primary inc ement division ma be ne es ary t o divide the inc ement

t o a manag ea le mas

Al proc s es an o e ations ups r am of the sampl ng location shal be ex mined for charact eris ics

w hich could prod c pe iodic v riations in belt lo ding or q alty an w hich ma coincide with the

o e ation of the primary sample s Such pe iodicity ma arise from the cycle of o e ations or fe de

sy st ems in use If it is not pos ible t o el minat e coincidenc betwe n the plant o e ation cycle an the

samplng cycle, s ratif ied ran om sampl ng within fix ed mas or time int erv ls shal be ado t ed

5.2 Time-basis sampl ng

5.2.1 Method of taking primary incr ements

In orde that he inc ement mas is pro ortional t o the co l flow rat e in me hanical samplng, the spe d

of the cutt er shal be cons ant throughout the sampl ng ofthe entir sub-lot ( e 6.8.1)

Primary inc ement shal be taken at pr set eq al time int erv ls throughout the lot or sub-lot If the

calculat ed n mbe of inc ement has be n taken befor the han l ng has be n complet ed, ad itional

inc ement shal be taken at the same int erv l u ti the han l ng o e ation is complet ed

is the mas of the sub-lot, in t onnes;

G is the ma imum flow rat e on the convey r belt, in t onnes pe hour;

n is the n mbe of primary inc ement in the sample ( e 4.3.4)

In orde t o minimiz the p s ibi ty of any bias being introd c d, a ran om s art within the firs

samplng int erv l is r commen ed

5.2.3 Mas of increment

The mas of the primary inc ement cor espon ing t o the a e ag e flow rat e (t otal mas / pe ating

time) of the co l s r am shal be not les than the minimum a e ag e inc ement mas calculat ed from

F ormula (7)

The mas of the inc ement shal be pro ortional t o the flow rat e of the co l s r am at the time it is taken

5.3 Mas -basis sampl ng

5.3.1 Method of taking primary incr ements

The r q ir d n mbe of inc ement shal be taken b sampl ng at a pr set mas int erv l This int erv l

shal not be chang ed d ring the samplng of the sub-lot

If the calculat ed n mbe of inc ement has be n taken befor the han lng has be n complet ed,

ad itional inc ement shal be taken at he same int erv l u ti the han l ng o e ation is complet ed

5.3.2 S mplng inter val

The inc ement shal be spr ad u iformly on a t onnag e b sis throughout the mas of thelot or sub-lot

The mas int erv l, ∆m, in t onnes, betwe n taking inc ement b mas -b sis sampl ng is det ermined

is the mas of the sub-lot, in t on es;

n is the n mbe of primary inc ement in the sample

The mas int erv l betwe n inc ement shal be eq al t o or smal e than that calculat ed from the

n mbe of inc ement spe if ied in 4.3.4, in orde t o ensur that the n mbe of inc ement wi l be at

leas the minimum n mbe spe ified

In orde t o minimiz the pos ibi ity of introd ction of bias, a ran om s art within the f irs samplng

int erv l is r commen ed

5.3.3 Mas of increment

The mas es of the individ al inc ement cons ituting the sample shal be almos cons ant, i.e the

coefficient of v riation shal be les than 2 %, and the e shal be no cor elation betwe n the flow rat e

at the time oftaking the inc ement an the mas of the inc ement cons ituting the sample The method

for det ermining w hethe or not these c it eria ha e be n met is spe if ied in Annex A These c it eria ma

be achieved b eithe of the folowing proc d r s:

a) take primary inc ement of almos cons ant mas using a cutt er with v ria le spe d, w hose

cutt er spe d is cons ant w hie cut ing the s r am but can be r gulat ed, inc ement b inc ement, in

pro ortion t o the flow rat e of the co l at hep int of samplng;

b) take primary inc ement using a fix ed-spe d cutt er with subseq ent division of the in ivid al

inc ement t o almos cons ant mas at a practical s ag e prior t o the cons itution of the sample

NOTE Proced re a) is prefer ed for fal ing-stre m sampler ; only proced re b) can b used for c os -b lt

sampler

5.4 Stratified random sampl ng

5.4.1 General

Cyclcal v riations in co l q alty ma oc ur d ring samplng Eve y efort shal be made t o el minat e

coincidenc of the cycle with the taking of inc ement in sy st ematic sampl ng, be it time- or mas -b sis

If this cannot be done, a bias wi l inv ria ly be introd c d that ma be of u ac epta le pro ortions

In such cir ums anc s, s ratified ran om samplng ma be ado t ed in w hich, for each time or

mas int erv l, the actual taking of the inc ement is displac d b a random amount of time or mas

r spe tively, subje t t o the lmitation that it shal be taken befor that int erv l has ex ir d

During s ratif ied ran om samplng, it is p s ible that two inc ement wi l be cole t ed ve y close

that the discharg e bin of the primary sample be of sufficient siz t o ac ept a minimum of two primary

inc ement at the ma imum flow rat e

5.4.2 Time-basis stratified random sampl ng

The sampl ng int erv l shal be det ermined as in 5.2.2 an the inc ement mas as in 5.2.3 Prior t o the

s art of each samplng int erv l, a ran om n mbe betwe n z ro an the sampl ng int erv l shal be

g ene at ed The inc ement shal then be taken aft er the time in icat ed b the ran om n mbe The

mas of the inc ement shal bepro ortional t o theflow rat e of theco l ( e 5.2.3)

5.4.3 Mas -basis stratified rand m samplng

The samplng interv al shal be determined as in 5.3.2 an the inc ement mas as in 5.3.3 Prior to the s art

of ea ch samplng interv al, a ran om n mbe betwe n z ro an the mas ofthe samplng interv al (ton es)

shal be gene ated The inc ement shal be taken after the p s age ofthe mas of co l in icated b the

ran om n umbe The mas of the inc ement shal be in epen ent ofthe flow rate of the co l ( e 5.3.3)

5.5 Referenc e sampl ng

R efe enc samples for bias t es ing of a samplng sy st em shal be taken b the st op ed-belt method

given in ISO 1 9 9-8t o ena le che king for bias

6 Desig n of mechanical samplers

From the initial s ag es of design an cons ruction of a sy st em, it is es ential that d e conside ation be

given t o the safety of the o e at ors Al safety codes a plca le at thesit e w he e the eq ipment is t o be

ins al ed shal be r spe t ed

It is es ential that r lev nt information conc rning the sampl ng scheme( ) (Cla use 4), the method of

samplng (Clause 5)an sample pr p ration ( e ISO 1 9 9-4 ), as wel asinformation a out the design

an o e ation of the co l han l ng plant ar a ai a le t o the designe

6.3 Basic r equir ements

It is important that the co l-han l ng plant be designed and engine r d t o pro ide adeq at e spac an

satis act ory o e ating and sampl ng con itions for the sampl ng sy st em The importanc of conside ing

the r q ir ment of the samplng sy st ems from the f irs s ag e of main plant design cannot be o e

s r s ed It is ne es ary t o ensur that any subseq ent chang es do not afe t the o e al pe formanc

an r l a i ty of the samplng syst em Designe s shal take he d of the che ks that ne d t o be car ied

out d ring o e ation Faci ities for taking r pl cat e samples an st op ed-belt amplng shal be inclu ed

at the design s ag e

The sy st em shal be r adi y ac es ible throughout t o faci tat e inspe tion, thorough cleaning, r p irs or

che king ex e iment , e.g t es s for bias

NOTE F or a mas -b sis sampling system, it is useful for provision to b made for conver ion from mas -b sis

t o time-b sis sampling in the event hat the mas -monitoring device bre ks down