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है”ह”ह

IS 9127-5 (2004): Methods for Petrographic analysis ofcoal, Part 5: Microscopical determination of thereflectance of vitrinite [PCD 7: Solid Mineral Fuels]

IS 9127( Part 5 ) :20041s07404-5:1994

Indian Standard

METHODS FOR THE PETROGRAPHIC ANALYSISOF BITUMINOUS COAL AND ANTHRACITE

PART 5 METHOD OF DETERMINING MICROSCOPICALLY THEREFLECTANCE OF VITRINITE

( First Revision)

Ics 73.040

@ BIS 2004

BUREAU OF INDIAN STANDARDSMANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG

NEW DELHI 110002

November 2004 Price Group 6

Solid Mineral Fuels Sectional Committee, PCD 7

NATIONAL FOREWORD

This Indian Standard ( Part 5 ) ( First Revision ) which is identical with ISO 7404-5:1994 ‘Methodsfor the petrographic analysis of bituminous coal and anthracite — Part 5 : Method of determiningmicroscopically the reflectance of vitrinite’ issued by the International Organization for Standardization( ISO ) was adopted by the Bureau of Indian Standards on the recommendations of the Solid MineralFuels Sectional Committee and approval of the Petroleum, Coal and Related Products Division Council.

This standard was first published in 1987 which was largely based on lSO/DIS 7404-5. ISO 7404-5 wasfirst published in 1984 and then revised in 1994 as ISO 7404-5 :1994. The Committee, therefore,decided to revise this Indian Standard to completely align it with ISO 7404-5:1994 and publish as dual 4,number standard. Consequently, the title has been modified. ~j

The text of ISO Standard has been approved as suitable for publication as an Indian Standard without

I

i

deviations. Certain conventions are, however, not identical to those used in Indian Standards. Attentionis particularly drawn to the following: ,“-

a) Wherever the words ‘International Standard’ appear referring to this standard, they should beread as ‘Indian Standard’.

b) Comma ( , ) has been used as a decimal marker while in Indian Standards, the current practiceis to use a point ( . ) as the decimal marker.

CROSS REFERENCES

In this adopted standard reference appears to certain International Standards for which IndianStandards also exist. The corresponding Indian Standards which are to be substituted in their placeare listed below along with their degree of equivalence for the editions indicated.

International Standard Corresponding Indian Standard Degree of Equivalence

ISO 7404-1 :1994 Methods for the IS 9127 ( Part 1 ) :1992 Methods of Technically equivalentpetrographic analysis of bituminous petrographic analysis of coal: Part 1 with minor deviationscoal and anthracite — Part 1 : Definition of terms relating toVocabulary petrographic analysis of coal ( first

revision )

ISO 7404-2:1985 Methods for the IS 9127 ( Part 2 ) :2002 Methods Identicalpetrographic analysis of bituminous for the petrographic analysis ofcoal and anthracite — Part 2 : bituminous coal and anthracite:Method of preparing coal samples Part 2 Method of preparing coal

samples ( first revision )

In reporting the results of a test or analysis made in accordance with this standard, if the finalvalue, observed or calculated, is to be rounded off, it shall be done in accordance with IS 2 : 1960‘Rules for rounding off numerical values ( revised)’.

““?

IS 9127 (Part 5) :2004

1s0 7404-5:1994

/ndian Standard

METHODS FOR THE PETROGRAPHIC ANALYSISOF BITUMINOUS COAL AND ANTHRACITE

PART 5 METHOD OF DETERMINING MICROSCOPICALLY THEREFLECTANCE OF VITRINITE

( First Revision)

1 scope

This part of ISO 7404 specifies the method for deter-mining microscopically the maximum and randomreflectance in oil of polished surfaces of the vitrinitecomponent of coals. The method is applicable to ei-ther coals from single seams or coal blends coveringthe whole range of bituminous coal and anthracite.By itself, this method is unsuitable for determining theproportion of components in a blend, particularlywhen the components have dissimilar measurablevitrinite contents.

The method necessitates the identification of vitriniteby the operator. Reflectance measurements onvitrinite obtained by interpreting the results of a com-puterized automated system of microscopic analysisare outside the scope of this part of ISO 7404.

2 Normative references

The following standards contain provisions which,through reference in this text, constitute provisionsof this part of ISO 7404. At the time of publication, theeditions indicated were valid. All standards are subjectto revision, and parties to agreements based on thispart of ISO 7404 are encouraged to investigate thepossibility of applying the most recent editions of thestandards indicated below. Members of IEC and ISOmaintain registers of currently valid InternationalStandards.

ISO 7404-1:1994, Methods for the petrographicanalysis of bituminous coal and anthracite — Part 1.“Vocabulary.

ISO 7404-2:1985, Methods for the petrographicanalysis of bituminous coal and anthracite — Part 2.”Method of preparing coal samples.

3 Definitions

For the purposes of this part of ISO 7404, the defi-nitions given in ISO 7404-1 apply.

4 Principle

Light, with a wavelength of 546 nm, reflected at nearnormal incidence from a specified area of well-polished vitrinite, measured under oil immersion usinga photomultiplier (or sirhilar device), is compared withlight reflected under identical conditions from a num-ber of standards of known reflectance. Because dif-ferent vitrinite particles within a single coal seaminvariably differ slightly from one another in opticalproperties, enough readings on different particles aretaken to ensure that the results are representative.

5 Materials

5.1 Immersion oil, of a non-drying, non-corrosivetype, with a refractive index of 1,5180 * 0,0004 at23 “C and a wavelength of 546 nm and with a tem-

‘n f less than 0,0005 K-1.perature coefficient – ~ o

1

IS 9127 (Part 5) :2004

1s0 7404-5: 1994

NOTES

1 Oil from a bottle which was first opened more than ayear previously should not be used unless the refractiveindex has been checked,

2 The oil should not contain polychlorinated biphenyls orother

5.2

toxic components.

Calibration standards

5.2.1 Reflectance standards, consisting of polishedsurfaces of materials that

a) are isotropic (or basal sections of uniaxial min-erals);

b) are durable and resistant to corrosion;

c) have constant reflectance over a long period;

d) are free from inclusions, grain boundaries, dis-continuities, internal flaws and fractures;

e) have negligibly low absorptance.

To avoid significant amounts of light other than thatreflected from the top surface returning to the objec-tive, the body of the standard shall be either deeperthan 5 mm or wedge-shaped. The lower surface shallbe matt if it makes an angle of less than 10“ with theupper polished surface.

The sides shall be shielded from external light.

The reflectance of the standards shall be in the regionof the reflectance of the coal to be measured. Use atleast three such standards with well-spacedreflectance (see note 3).

If a coal with a reflectance greater than 2,0 YO is tobe measured, use one or more additional standardswith reflectance greater than 2,0 Yo.

Table 1 gives mean values of refractive index and ofreflectance for reflectance standards in common use.Determine exactly the reflectance of any optical glassstandard by using a comparable standard or by meansof a determination of the refractive index.

Where the refractive index, n, and (if significant) theabsorptance, u, of the standard material are known fora wavelength of 546 nm, calculate the reflectance, R,as a percentage using the equation

R= (n-l,518)2+n2a2 ~ ,00

(n.+ 1,518)2 + n2a2

Table 1 — Reflectance standards in common use

Reflectance in

Refractiveimmersion oil

Designationindex

of 1,518 at546 nm (see

5.1)

0/0

Optical glasses 1,70 to 1,97 0,32 to 1,66

Spinel 1,73 0,42

Leucosapphire 1,77 0,59

Yttrium aluminium1,84 0,92

garnet (YAG)

Gadolinium gallium 1,98 1,73garnet (3G)

Diamond 2,42 5,28

Silicon carbide 2,66 7,50

Where the refractive index is not known, or where itis suspected that the surface properties may not ex-actly match the nominal bulk properties, determinethe reflectance by careful comparison with a standardof known reflectance (see note 4).

NOTES

3 For measuring a coal reflectance of about 1,09’., stan-dards with reflectance of approximately 0,6 %, 1,0 % and1,6 % should be used.

4 Standards need careful cleaning to avoid scratching thepolished surface. Tarnishing may also occur with somestandard materials, particularly glasses. When the surfacebecomes scratched, or when comparison with the otherstandards shows that the reflectance value has changed,polishing is necessaty.

5.2.2 Zero standard

NOTE 5 A suitable non-reflecting standard consists of acoal or opaque resin block with a hole about 5 mm in di-ameter and 5 mm deep, drilled in its upper surface and filledwith immersion oil. Alternatively, optical glasses ofrefractive index lower than that of the immersion oil maybe used.

6 Apparatus

6.1 Binocular reflected light microscope withphotometer.

NOTE 6 The reference letters refer to figure 1.

2

6.1.1 Light source (A).

Any light source with a stable output may be used; aquartz halogen lamp with a rating of 100 W is rec-ommended.

6.1.2 Polarizer (E) (optional): A sheet or prismpolarizer.

6.1.3 Light-controlling apertures, consisting oftwo variable diaphragms, one of which is focused onthe back focal plane of the objective [illuminator ap-erture (C)] and the other on the surface of the speci-men [field stop (F)]. It shall be possible to centre bothdiaphragms on the optical axis of the microscopesystem. The optical parts of a typical reflectancemeasuring microscope are shown in figure 1,

NOTE 7 The component parts may not always be in thesame sequence.

6.1.4 Vertical illuminator, Berek prism, simplecoated glass plate or Smith illuminator (a combinedmirror and glass plate). Typical light paths are shownin figure 2.

6.1.5 Objective (l), Strain-free objective, designedfor use with polarized light and an immersion oil ofrefractive index 1,518, with a magnification of be-tween x 25 and x 60 and a low value for the parasiticreflection (see 8.2.3).

NOTE 8 The diameter of the objective should be as largeas possible. A larger objective gives increased light inten-sity, thereby reducing the signal amplification and hence theelectronic noise; it also makes it possible to work with asmaller measuring aperture.

6.1.6 Eyepieces (L), Two viewing eyepieces, oneof which is fitted with crosslines which may bescaled, such that the total magnification given by theobjective, eyepiece and tube factor (if any) is betweenx 250 and x 750.

NOTE 9 A third eyepiece (M) may be necessary in thelight path leading to the photomultiplier.

6.1.7 Microscope tube, with the following features:

a) measuring aperture (N) which restricts the lightreaching the photomultiplier to that reflected froman ~area of the specimen (J) less than 80 Vmz and

which can be aligned with the crosslines in theviewing eyepiece;

b) a means of optically isolating the viewing eye-pieces if they permit the entry of extraneous lightduring measurement;

c) adequate blackening

NOTE 10 Subiect to the

IS 9127 (Part 5) :2004

1s0 7404-5:1994

to absorb stray light.

above precautions, part of thelight beam may ‘be diverted to the eyepieces or to a tele-vision camera for continuous observation during reflectancemeasurement.

6.1.8 Filter(s) (0), with a peak transmittance in therange of 546 nm ~ 5 nm and a half-peak

transmittance band of less than 30 nm.

NOTE 11 The filters should be inserted into the light pathimmediately before the photomultiplier.

6.1.9 Photomultiplier tube (P), fitted in a housingattached to the microscope, permitting the lightpassing through the measuring aperture and filter tofall onto the photomultiplier window.

NOTES

12 The photomultiplier tube should be of a type rec-ommended for low light-level applications, and should haveadequate sensitivity at 546 nm with low dark current. Itshould have a linear response over the range of themeasurement and the output should be stable over periodsof Up to 1 h.

13 A 50 mm diameter straight tube with an end windowand containing 11 dynodes is frequently used.

6.1.10 Microscope stage (K), fitted with a mech-anical stage capable of advancing the specimen by0,5 mm steps in the X and Y directions and providedwith a means for making small adjusting movements.For maximum reflectance, the stage shall be capableof being rotated through 360” perpendicular to theoptical axis, and being centred by adjusting either thestage or the objective.

6.2 Stabilized d.c. power supply unit for the lightsource.

The following characteristics have been found to besatisfactory:

a) a lamp output of between 90 ‘%o and 95 YO of ratedoutput;

b) an output variation of less than 0,02 Y. for a sup-ply variation of 10 ‘%0;

c) a ripple content at full load of less than 0,07 9!o

peak to peak;

d) a temperature coefficient of less than0,05 % K-1.

r-l

IS 9127 (Part 5) :2004

1s0 7404-5: 1994

A LampB Collector lenaC Illuminator apertureD Heat filterE PolarizerF Field stopG Field-stop focusing lensH Vertical illuminatorI ObjectiveJ SpecimenK StageL Viewing eye-piecesM Third eye-pieceN Measuring apertureO 546nm interferencefilterP Photomultiplier tube

—P

~o—N

.Figure 1 — Optical pans of a typical reflectance measuring microscope

4

IS 9127 (Part 5) :2004

1s0 7404-5:1994

A 8C D E F

ABcDEFG

HI

Lamp filwnentCollector lensIlluminator ●perture (position of filamant imaga)Fiald atopField-atopfoouaing IonsBwek prismBackfocal plane of objeotive (position of imagaa of thefilamant and the illuminator aperture)ObjectiveSurfaoa of apaciman (position of image of fiald atop)

●l Ber*k prism vwticd Illuminator

-! JThin glaaa reflector

Coetad glaaa plate

I

/

! II 1f

D E D E

J-—>_A. -&-r-— G

&- H

I ,SP_b) Glaaaplot. illuminator c) Smith Illumlnetof

Figure 2 — Typesof verticalilluminators

5

IS 9127 (Part 5):2004

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6.3 Stabilized d.c. voltage power supply unit forthe photomultiplier tube,

The following characteristics have been found to besatisfacto~:

a) an output variation of less than 0,05 ‘Mo for a10 ‘Yo variation in supply voltage;

b) a ripple content at full load of less than 0,07 %peak to peak;

c) a temperature coefficient of less than0,05 ‘%. K-l;

d) a change in load from zero to full rated load thatcauses less than 0,1 YO variation in output voltage.

NOTE 14 If the mains voltage at peak periods is expectedto fall below 90 ‘XO of the normal rated value, a suitably ratedstabilizing autotransformer should be connected betweenthe mains power point and the two stabilized power sup-plies (see 6.2 and 6.3).

6,4 Display, comprising one of the following de-vices:

a) galvanometers with a minimum sensitivity of10-10 A/mm;

b) a chart recorder;

c) a digital voltmeter or digital indicator.

The device used shall be so adjusted that its responsetime for full-scale deflection is less than 1 s, and shallbe capable of resolution of 0,01 YO reflectance. A fa-cility for backing-off the small positive voltage due toglare and photomultiplier dark current shall be pro-vided.

NOTES

15 It is an advantage to have a maximum seeking facilityincorporated with the digital voltmeter or digital indicator toenable values for the maximum reflectance to be indicatedwhen the specimen on the stage is rotated. Individualreflectance values may also be stored electronically ormagnetically for later processing.

16 A low noise variable gain amplifier may be used ifnecessary to amplify the signal from the photomultiplierbefore it is passed to the display.

6.5 Sample mounting apparatus,slides, modelling clay and Ievelling device.

comprising

7 Preparation of coal sample

Prepare and polishISO 7404-2.

8 Procedure

a particulate block as described in

8.1 Settingup the apparatus

NOTE 17 In 8.1.3 and 8.1.4 letters in parentheses relateto the key in figure 1.

8.1.1 Starting procedure

Ensure that the room temperature remains within the ,range 18 “C to 28 “C. Switch on the lamp, power isupplies and other electrical parts of the apparatus.

4Set the power supply to the photomultiplier to within {the voltage range recommended by the manufacturer ‘.of the particular photomultiplier tube. Allow about

.

30 min to elapse for stability of the apparatus to beattained prior to making any measurements.

8.12 Adjusting the microscope for random ormaximum measurements

If random reflectance measurements are to be made,remove the polarizer. If maximum reflectancemeasurements are to be made, set the polarizer tozero if using a glass plate or Smith illuminator, or to45° if using a Berek prism. If a sheet polarizer is used,check and replace it if it shows significant discolor-ation. If the microscope has an analyser, remove thisfrom the light path.

8.1.3 Illumination

Apply immersion oil to the polished surface of apa~iculate coal block, mounted and Ievelled on a glassslide, and place the specimen on the stage.

Check that the microscope has been correctly ad-justed for Kohler illumination. Adjust the illuminatedfield by means of the field stop (F) so that its diameteris about one-third of the diameter of the full field.Adjust the illuminator aperture (C) to reduce glare butwithout reducing the light intensity excessively. Onceadjusted, do not alter the size of the apertures.

8.1.4 Alignment

Centre and focus the image of the field stop, centrethe objective (1)with respect to the axis of rotation ofthe stage and adjust the centre of the measuring ap-erture (N) to be coincident with either the crosslinesor a known datum point in the viewing system.

6

IS 9127 (Part 5):2004

1s0 7404-5:1994

If it is not possible to view the image of the measur- backing-off control (see 6.4). Continue making adjust-ing aperture superimposed on the specimen, select a ments using the highest standard as in 8.2.1 and thefield of view that contains a small bright inclusion, zero standard in turn until no futiher adjustment issuch as a crystal of pyrite, and align this directly under necessary.the crossline. Adjust the centring of the measuringaperture (N) until the photomultiplier reading is at its 8.2.4 Linearity of the signal from thehighest value. photomultiplier

8.2 Checking the reliability and calibrationof the apparatus

8.2.1 Stability of apparatus

Place the standard with the highest reflectance valueunder the microscope and focus under oil immersion.

Adjust the amplifier or the voltage to thephotomultiplier until the reading on the display has thesame numerical value as the reflectance of the stan-dard (for example, 173 mV might correspond to areflectance of 1,73 ?40). Ensure that the signal is stableby checking that the reading changes by less than2 ‘Yo relative to the first reading within a period of15 min.

8.2.2 Variation in reading on rotating areflectance standard on the stage

Place a standard with a reflectance in oil between1,6 Y. and 2,0 ‘Y. on the stage and focus under oilimmersion. Slowly rotate the stage and verify that themaximum variation in the reading is less than 2 ‘Yo

relative to the reflectance of the standard being used.If this value is exceeded, check the Ievelling of thestandard, and ensure that the stage is perpendicularto the optical axis and that, it rotates in a fixed plane.If these checks do not reduce the variation to lessthan 2 ‘%., the mechanical stability of the stage and thegeomet~ of the microscope have to be checked bythe manufacturer.

8.2.3 Correction for parasitic reflections andphotomultiplier dark current

Place the zero standard on the stage and note thereading that represents the sum of the photomultiplierdark current and the parasitic reflections. If thephotomultiplier dark current and parasitic reflectionsexceed 0,04 ‘Yo reflectance in total, determine theirrelative proportions by interrupting the light reachingthe photomultiplier so that any residual signal is thendue to the photomultiplier dark current. Check thesetting of the illuminator aperture and change thephotomultiplier tube andlor the objective, as appro-priate, so that the total signal is below 0,04 Y.

reflectance. When the total signal is below 0,04 ‘%.

reflectance, adjust the display to zero using the

Measure the reflectance of the other standards whilstmaintaining the constant settings of the voltage sup-plies and light-controlling apertures in order to checkthat the measuring system has a linear response inthe range to be measured and that the standardsmatch their calculated value. Rotate each standard toensure that the mean reading attained matches thecalculated value. If the reading for any standard differsfrom its calculated reflectance value by more than2 ‘Y. relative to the calculated value, clean the stan-dard and repeat the standardizing process. Repolishany standard still displaying a reflectance differingfrom its calculated value by more than 2 ‘%..

If the reflectance of the standards still do not give alinear plot, check the linearity of the photomultipliersignal using standards from other sources. If these failto give a linear plot, check the linearity of the signalby means of several calibrated neutral density filtersto reduce the luminous flux by known amounts. If thesignal from the photomultiplier is confirmed to benonlinear, reduce the photomultiplier voltage by 50 Vand recheck. If the signal is still nonlinear, check thesize of the measuring aperture and if necessary re-duce it, If rechecking still shows the signal to benonlinear, replace the photomultiplier tube and carryout further checks as necessav to achieve linearityof the signal.

8.2.5 Calibration of the apparatus

Having established the reliability of the apparatus,ensure that the display gives the correct readings forthe zero standard ancj the three reflectance standardsin the region of th~ reflectance of the coal to bemeasured, by carrying out the procedures specified in8.2.1 and 8.2.4. The reflectance of each standardshown on the display apparatus shall not differ fromits calculated value by more than 2 Y. relative to thecalculated value.

8.3 Measurementof the reflectanceofvitrinite

8.3.1 General

The procedure for measuring maximum reflectance isspecified in 8.3.2 and that for random reflectance isspecified in 8.3.3. In these subclauses the term

1,,,

:.,’

7

IS 9127 (Part 5) :2004

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vitrinite refers to one or morethe vitrinite group.

of the submacerals in

As explained in the last four paragraphs of the intro-duction, the choice of the submacerals on which themeasurements are made affects the results and con-sequently it is important to decide on whichsubmacerals to measure reflectance and to identifythem when reporting the results.

8.3.2 Measurement of the maximum refieotanceof vitrinite in oii

Ensure that the polarizer is fitted to the microscopeas specifed in 8.1.2 and that the appropriate checkson the apparatus have been made as specified in 8.1and 8.2.

Immediately after calibrating the apparatus, place aIevelled polished block prepared from the sample tobe tested on the mechanical stage to allow measure-ments to be made starting at one corner of the areato be traversed, apply immersion oil to the surfaceand bring the specimen into focus.

Move the specimen slightly using the mechanicalstage until the crosslines are focused on a suitablearea of vitrinite. Ensure that the measuring area con-tains no cracks, polishing defects, mineral inclusionsor relief effects, and is away from maceral boundaries.

Allow the light to pass to the photomultiplier and ro-tate the stage through 360” at a rotational frequencynot exceeding 10 rein-1 Record the highestreflectance reading obtained during the stage rotation.

NOTE 18 During rotation of the block through 360”, ide-ally two identical maximum readings should be obtained. Ifthe two readings differ significantly, the reason should besought and the fault corrected. Occasionally air bubbles inthe oil pass into the measuring area causing erraticreadings. If air bubbles are seen or suspected, ignore thereading and remove tha air bubbles by racking down thestage, wiping the front element of the objective lens witha lens tissue, adding a drop of oil to the surface and refo-cusing the specimen.

Traverse the specimen in the Xdirection stepwiseusing a step length of 0,5 mm. If the intersection ofthe crosslines covers a coal particle, use the mech-anical stage to move the specimen, if necessary, sothat the measuring area coincides with a suitable areaof vitrinite and make a measurement. Return themechanical stage to its original position and continueto make measurements at intervals of 0,5 mm. At theend of a traverse, move the specimen to the begin-ning of the next traverse keeping to an interline dis-tance of at least 0,5 mm. Choose the precise interlinedistance to ensure that the measurements are evenly

distributed over the surface of the block. Continuemaking reflectance measurements using this sam-pling procedure.

At 15 min intervals (or not more than 50 counts), re-check the calibration of the apparatus using the stan-dard nearest in reflectance to that of the highestreflecting vitrinite in the specimen (see 8.2.5). If thereflectance of the standard differs from its theoreticalvalue by more than 2 % relative to the theoreticalvalue, discard the last set of readings and repeat themafter recalibrating the apparatus using the full rangeof standards.

Make reflectance measurements on the vitrinite untilthe required number has been recorded. If, for 98 YO

of the measurements, the range of reflectance valuesis

a)

b)

c)

less than 0,35 %, calculate the mean ref Iectance r!

on the basis of 100 measurements;~,,

between 0,35 % and 0,70 Yo, calculate the meanreflectance on the basis of at least 500 measure-ments;

greater than 0,70 %, calculate the meanreflectance on the basis of at least 1000measurements.

8.3.3 Measurement of the random reflectance ofvitrinite in oli

Adopt the same procedures as specified in 8.3.2, butmake the measurements without the polarizer andwithout rotation of the sample block. Calibrate theapparatus as specified in 8.2.5.

Make reflectance measurements on the vitrinite untilthe required number has been recorded. If, for 98 YO

of the measurements, the range of reflectance valuesis

a)

b)

c)

9

less than 0,40 ‘%, calculate the mean reflectanceon the basis of 100 measurements;

between 0,40 % and 0,80 Yo, calculate the meanreflectance on the basis of at least 500 measure-ments;

greater than 0,80 %, calculate the meanreflectance on the basis of at least 1000measurements,

Expression of results

The results may be reported as individual values or asnumbers of measurements in intervals of 0,05 %

8

reflectance (1/2 V-step) or in intervals of 0,1070reflectance (V-step). Calculate the mean reflectanceand the standard deviation of the distribution as fol-lows.

If individual readings are repotled, calculate the meanmaximum or mean random reflectance percentage,R, and the standard deviation, a, from equations (1)and (2) respectively.

zRii?=~ ...(1)

J“n?- (D)*u=

n(n–1). . . (2)

where

Ri is the ith individual reading of reflectance;

n is the number of measurements.

If the results are reported as the number ofmeasurements in 1/2 V-steps or V-steps, the corre-sponding equations are given as follows:

R=

(J=

where

Ri

Xi

m. . (3)

,. (4)

is the mid-value of the 1/2 V-step or V-step;

is the number of reflectance measure-ments in the 1/2 V-step or V-step.

Record the submacerals of vitrinite to which the valueof R refers, whether maximum or random reflectancemeasurements were made and the number of pointsmeasured. The percentage of the vitrinite in each 1/2V-step or V-step may be plotted as a histogram. Anexample of a suitable method of expressing results isshown in table 2 and the corresponding histogram isshown in figure3.

NOTE 19 A V-step has a range of 0,1 % reflectance anda 1/2 V-step a range of 0,05 % reflectance. In order to avoidoverlap of reflectance values expressed to two decimalplaces, the ranges of values belonging to selected V-stepsand 1/2 V-steps are, for example, as follows:

IS 9127. (Part 5) :20041s0 7404-5:1994

V-step: 0,60 to 0,69; 0,70 to 0,79; etc. (inclusive)

1/2 V-step: 0,60 to 0,64; 0,65 to 0,69; etc. (inclusive)

The mid-point of range 0,60 to 0,69 is 0,645.

The mid-point of range 0,60 to 0,64 is 0,62.

Table 2 — An example of a method of expressing .the results

Sample No. 1

Reflectance meaaured Random

Vitrinfte aubmacarals Telocollinite (60 %) and(proportion of measure- desmocollinite (40 Y.)

ments):

Reflectance 1)Number of Percentage

observations observations

0,40 to 0,440,45 to 0,490,50 to 0,540,55 to 0,590,60 to 0,640,65 to 0,690,70 to 0,740,75 to 0,790,80 to 0,840,85 to 0,89 2 —

0,90 to 0,94 12 20,95 to 0,99 12 21,00 to 1,04 15 31,05 to 1,09 14 3l,lotol ,14 39 8l,15tol ,19 78 161,20 to 1,24 47 91,25 to 1,29 39 81,30 to 1,34 18 41,35 to 1,39 20 41,40to 1,44 23 51,45 to 1,49 29 61,50 to 1,54 66 131,55 to 1,59 65 131,60 to 1,64 13 31,65 to 1,69 8* 21,70 to 1,741,75 to 1,791,80 to 1,841,85 to 1,891,90 to 1,941,95to 1,99

rotal number of measurements, n: 500

Mean reflectance, R: 1,32 %

Standard deviation of the distribution, u: 0,20%

1) Upper and lower limits can be changed as appropri-ate.

9

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Sample number

Date

Mean maximum reflectance, ‘Y.

Mean random reflectance, %

Standard deviation

Vitrinite submacerals (proportion)

Number of measurements

1’

78-11-03

—

1,32

0,20

Telocollinite (60 Y.) and desmocollinite(40 %)

500

40”

30 -

20 “

m-

1

0,4 0,5 1,0 1,5 2

Maximum reflectance, %1)Random reflectance, %!)

Dalate ●s ●ppropriate.

Figure 3 — Hktogram plotted from the results given in table 2

10 Precision , where at is the theoretical standard deviation.

The repeatability depends on a number of factors in-cluding

10.1 Repeatabilitya)

The repeatability of the determination of the meanmaximum or mean random reflectance is that value

b)of the difference between two single determinationseach based on the same number of measurementscarried out by the same operator on the same block c)using the same apparatus, below which 95 ‘Yo of suchdifferences are expected to lie. The repeatability isgiven by the formula

the limited accuracy in setting the calibration bymeans of the reflectance standards (see 8.2.5);

the permissible drift in the calibration during themeasurements (see 8.3.2);

the number of measurements made and therange of reflectance occurring within the vitriniteeven in a single coal seam.

({)22ut The combined effect of these factors can be ex-pressed as a standard deviation of the’ mean

10

IS 9127 (Part 5) :2004

1s0 7404-5:1994

reflectance of up to 0,02940 for a single seam coal.This corresponds to a repeatability of up to 0,06940.

10.2 Reproducibility

The reproducibility of the determination of the meanmaximum or mean random reflectance is that valueof the difference between two single determinationseach based on the same number of measurementscarried out by two different operators on two differentsubsamples taken from the same sample, using dif-ferent equipment, below which 95 YO of such differ-ences are expected to lie. The reproducibility is givenby the formula

([)2200

where 00 is the observed standard deviation.

Provided that operators are adequately trained in theidentification of vitrinite or the appropriatesubmacerals and that the reflectance of the stan-dards used are reliably known, determinations of themean reflectance by different operators in differentlaboratories show standard deviations in the order of0,03 Yo. The reproducibility is thus in the order of0,08 I%..

11 Test report

The test report shall include the following information:

a)

b)

c)

d)

e)

f)

g)

h)

i)

a reference to this part of 1.S0 7404;

all details necessa~ for identification of the sam-ple;

the name and address of the testing laboratory;

date of test;

the total number of measurements;

type of measurements made, i.e. maximum orrandom;

type and proportion of vitrinite submacerals usedin the determination;

the results obtained;

any other characteristics of the sample observedduring the analysis that may be relevant to theuse of the results.

,

11

IS 9127 (Part 5):2004

1s0 7404-5:1994

Annex A

(infmrnative)

Bibliography

[1] International Handbook of Coal Petrography, and Environmental Geochemistry, Drummond Building,

published by the International Committee for University of Newcastle, Newcastla-upon-Tyne, NEI 7RU,

Coal and Organic Petrology (lCCP). United Kingdom.

NOTE 20 The second edition (1963), together with the [2] ISO 7404-3:1994, Methods for the petrographicfirst supplement (1971, corrected and revised in 1985), analysis of bituminous coal and anthracite —second supplement (1975) and third supplement (1993) may Part 3: Method of determining maceral 9rOuPbe obtained from Professor D.G. Murchison, Fossil Fuels composition.

12

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Amend No. Date of Issue Text Affected

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