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IS 1528-22 (2007): Methods of Sampling and Physical Testsfor Refractory Materials, Part 22: Methods forDetermination of Permeability to Gases of Dense ShapedRefractoy Products [MTD 15: Refractories]

IS 1528 (Part 22) :2007ISO 8841:1991

Indian Standard

METHODS OF SAMPLING AND PHYSICAL TESTSFOR REFRACTORY MATERIALS

PART 22 METHOD FOR DETERMINATION OF PERMEABILITY TO GASES OF DENSESHAPED REFRACTORY PRODUCTS

Ics 81.080

@ BIS 2007

BUREAU OF INDIAN STANDARDSMANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG

NEW DELHI 110002

September 2007 Price Group 3

Refractories Sectional Committee, MTD 15

NATIONAL FOREWORD

This Indian Standard (Part 22) which is identical with ISO 8841 : 1991 ‘Dense, shaped refractoryproducts — Determination of permeability to gases’ issued by the International Organization forStandardization (ISO) was adopted by the Bureau of Indian Standards on the recommendation of theRefractories Sectional Committee and approval of the Metallurgical Engineering Division Council.

The text of ISO Standard has been approved as suitable for publication as an Indian Standard withoutdeviations. Certain conventions are, however, not identical to those used in Indian Standards.Attention is particularly drawn to the following:

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

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

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 theirplaces, are listed below along with their degree of equivalence for the editions indicated:

International Standard

ISO 6906 : 1984 Vernier calipersreading to 0.02 mm

ISO 5022 : 1979 Shaped refractoryproducts — Sampling and acceptancetesting

Corresponding Indian Standard

IS 3651 (Part 2) : 1985 Specification forvernier calipers: Part 2 Vernier caliperswith least count 0.02 mm (second revision)

IS 1528 (Part 7) : 1974 Methods ofsampling and physical tests for refractorymaterials: Part 7 Methods of samplingand criteria for conformity (first revision)

Degree ofEquivalence

TechnicallyEquivalent

do

For the purpose of deciding whether a particular requirement of this standard is complied with, thefinal value, observed or cal&lated, expressing the result of a test or analysis, shall be “rounded off inaccordance with IS 2 : 1960 ‘Rules for rounding off numerical values (revised)’. The number ofsignificant places retained in the rounded off value should be the same as that of the specified valuein this standard.

IS 1528( Part22) :2007ISO 8841:1991

Indian Standard

METHODS OF SAMPLING AND PHYSICAL TESTSFOR REFRACTORY MATERIALS

PART 22 METHOD FOR DETERMINATION OF PERMEABILITY TO GASES OF DENSESHAPED REFRACTORY PRODUCTS

1 Scope

This International Standard specifies a method for

the measurement of the permeability to gases of

dense, shaped refractory products.

NOTE 1 The method specified takes account of the dy-namic viscosity of the gas, and therefore the results ob-

tained may not be directly comparable with thoseobtained by earlier methods which took no account ofviscosity. The determination is generally made by thepassage of air. Other gases may be used when required,and the viscosities of air and nitrogen are given.

2 Normative reference

The following standard contains provisions which,through reference in this text, constitute provisionsof this International Standard. At the time of publi-cation, the edition indicated was valid, All standardsare subject to revision, and parties to agreementsbased on this International Standard are encour-aged to investigate the possibility of applying themost recent edition of the standard indicated below.Members of IEC and ISO maintain registers of cur-rently valid International Standards,

ISO 6906:1984, Vernier callipers reading to 0,02 mm.

3 Definition

For the purposes of this International Standard, thefollowing definition applies.

3,1 permeability of a material: The property bywhich the material allows a gas to pass through itwhen under a difference of pressure.

The permeability (~) is calculated using the follow-ing equation, given for the volume of gas passingthrough a test piece in a given time:

v7

where

p’

(

//

v

A

h

P

PI

172

NOTES

(p, + p,)‘ A ‘h –P2)” *P)1~’ * . . . (4)

is the volume of gas passing through thematerial, in cubic metres;

is the time, in seconds, in which that vol-ume of gas passes through the material;

is the permeability of the material, insquare metres;

is the dynamic viscosity, in pascal sec-onds, of the gas at the temperature of thetest;

is the cross-sectional area, in squaremetres, of the material traversed;

is the thickness, in metres, of the ma-

terial traversed;

is the absolute pressure, in pascals, ofthe gas;

is the absolute pressure, in pascals,where the gas enters the material;

is the absolute pressure, in pascals,where the gas leaves the material.

2 Equation (1) corresponds to Darcy’s Law, and is de-duced from the Hagen Poiseuille Law.

3 Since p is the pressure under which the volume of gasis measured, p = p, when operating under positivepressure, and p = p2 when operating under negativepressure.

4 The factor (pI + pJ/2p is usually very close to unityand may be neglected when operating with small pressuredifferences, e.g. when (pl – p2) is less than 1000 Pa.

IS 1528 (Part 22):2007ISO 8841:1991

Equation (1) may be rearranged as

(2)

Writing equation (2) in the units involved, the unit forpermeability is square metres, derived from

If, in equation (l), 6 is expressed in centimetres, Ain square centimetres and V in cubic centimetres(the units for the other quantities being unchanged),an alternative unit for permeability may be derived,namely square centimetres, However, since com-pound prefixes are not permissible, the conventionalprefixes may be used only with the unit square me-tres, thus 10-B cm2 = 10- ‘2m2 = lpm2.

4 Principle

A stream of dry gas is passed through the test piece,and the pressure drop across the test piece is re-corded for at least three different rates of flow. Fromthese values, and from the size and shape of the testpiece, the permeability of the material is determinedby calculation,

5 Apparatus

5.f General

The general layout of the apparatus is showndiagrammatically in figures 1 and 2. Figure 1 showsthe arrangement for the passage of gas underpressure and figure 2 for the passage of gas undersuction. The connecting piping shall be made ofglass in preference to rubber, and shall be as shortas possible, so that the pressure loss in the appa-ratus is very small when compared with the press-ure loss produced by the test piece.

5.1.1 Supply of gas (under pressure or suction),consisting of a reservoir of gas at constant pressure.

5.1.2 Test piece holder, with gas-tight seals at thesides of the test piece. Gas tightness shall be en-sured by a rubber membrane that is inflated to apressure of 0,2 N/mm* to 0,4 N/mm*. See figure 3.

NOTE 5 Modifications will be required if the alternativetest piece size (see note to 6.1) is used.

5.1.3 Llquld manometer, of the U-tube type, formeasuring the difference in pressure between thetwo faces of the test piece. The usual experimentalprecautions for this type of measurement shall betaken, so that the error in the pressure determi-nation does not exceed 1 ~0 (including error in

reading column height, meniscus error, error in theverticality of the manometer, and measurement ofthe density of the manometer liquid). The pressureshall be determined close to one face of the testpiece in the vessel containing the test piece holder(5.1.2).

NOTE 6 A lower pressure reading may result when thepressure away from the test piece is determined in theconnecting tubes.

5.1.4 Gas flow measuring equipment, consisting ofa sensitive floating flowmeter calibrated for a giventemperature and pressure of entry. The flowmetershall be accurate to within 2 O/.. The flowmeter shallbe calibrated periodically for the gas to be used, andonly the middle section of its measuring scale shallbe used.

For the measurement of permeability to air only, therate of air ffow is measured by the displacement of

air by water, using a graduated cylinder device anda chronometer.

5,1.5 Vernier callipers, in accordance withISO 6906.

5.1.6 Drying oven, capable of being controlled at11O”C*5”C.

5.1,7 Impermeable dummy test piece, for examplean aiuminium cylinder.

6 Test pieces

6.1 Dimensions

The test pieces shall50 mm + 0,5 mm and

be cylindrical, with diameterheight 50 mm * 0,5 mm. The

perpendicularity of the axis of the test piece to thefaces, and the paraHelism between the top and bot-tom faces of the test piece shall both be within0,5 mm.

NOTE 7 A 50 mm cube test piece may also be usedwhere necessary. In this case the test piece holder (seenote to 5.1.2) will need to be modified and the calculationof the results (see 8.3) will be slightly different.

6.2 Preparation

The test pieces shall be cut in such a way that nomaterial is included that was within 4 mm of a faceof the brick or item. The direction in which the testpieces are cut, relative to the direction of pressing,shall be stated in the test report.

The faces shall be freed from dust formed during thecutting, by brushing under a jet of water followingwet cutting, or by a jet of compressed air followingdry cutting.

2

IS 1528( Part22) :2007ISO 8841:1991

6.3 Drying

The test pieces shall be dried to constant mass inthe drying oven (5.1.6) at 110 “C + 5 ‘C. Beforemeasurement, the test pieces shall be allowed tocool to room temperature in a desiccator; the timeof cooling shall be at least 2 h

d11

KE’f

123

45

T30 3b

.+7f.,

5

Sourco of gas (comweaead !rascylinderor water rear?rvoir)Desiccator;or the gas -Floating flowmeters: (at O to Z30 cm3/min, (b) 200 cm3/min to1 500 cm31 min

Holder for cylindrical sampleU-tube menometer, filled with liquid

Figure1 — Arrangementof instrumentsformeasuringgaspermeability(measuredundera

pressurehead)

!L!x!-7 5 5

6

KEY

1234

567

21

\2

Entry of the gas, via a desiccatorHolder for cylindrical eamdeU-tube manometer filled &ith liquidFloating flowmeters: (a) O to 2C0 cm3/min, (b) 200 cm3/min to1500 cm3/minWoulff safety bottlesRegulating ventDiaphragm or water pump

Figure 2 – Arrangement of instruments formeasuring gas permeability (measured under

suction)

For preaaurameasurement J?!

Figure 3 – Test piece hoider

7 Procedure

7.1 Carry out a blank determination to estabiishthat the test rig is gas-tight using an impermeabledummy test piece (5.1.7) in the place of the normaitest piece,

7.2 Measure the diameter and the height of thetest piece to 0,1 mm, using the Vernier callipers(5.1.5).

7.3 Place the test piece in the holder (5.1.2), en-suring that the pressure on the rubber membrane issufficient to render the cylindrical surface of the testpiece gas-tight, This may be checked by increasingthe pressure on the membrane; there should be nochange in the pressure difference between the planefaces and no change in the rate of gas flow.

7.4 Determine the rate of flow through the testpiece for at least three different pressure dropsacross it. Calculate the permeability of the test piecefor each determination. (See clause 8.)

NOTE 8 Theee determination are to verify that the rateof ffow ie proportional to the pressure drop, because theequation ueed for the calculation (see clause 8) is onlyvalid for Iaminar flow.

IS 1528 (Part 22):2007ISO 8841:1991

7.5 If the calculated permeabilities at the threedifferent pressure drops differ among themselves bymore than 5 ~0, repeat the blank test, check theequipment and repeat the tests. If the repeat testsstilt differ by more than 5 ~o, state this in the testreport.

8 Expression of results

8.1 The permeability, expressed in square metresto two significant digik, is”

where

~

h

A

Ap

qv

kv

NOTE 9

given by the equation

(3)

is the dynamic viscosity, in pascal sec-onds’), of the gas passed through the testpiece at the temperature of the test;

is the height, in metres, of the test piece;

is the cross-sectional area, in squaremetres, of the test piece through whichthe gas has passed (see 7.2):

is the pressure difference across the testpiece, in pascals;

is the rate of flow, in cubic metres persecond, of gas through the test piece;

is a correction factor (see table 1) for theremoval of water vapour (used only if theair flow was measured by displacementof water),

For air temperatures from t6 “C to 24 “C thevalues for the dynamic viscosity of air (q) are given in ta-ble 1, and these may be used under the assumption thatthe pressure drop over the test piece is small (see note3 to clause 3). The values for the dynamic viscosity ofnitrogen are given in table 2, from 10 ‘C to 35 ‘C.

8.2 Equation (3) may be written in terms of theunits more likely to be directly read in the test. Thusthe value of the permeability, expressed in squarecentimetres, is given by

1) 1 poise =O,l Pas

2) 1 mmH20 = 9,807 Pa

h 4X106 1 q’ vp=rl ---

9,807Ap’ “ 60x 10%x 104

103 rcd2

2,16 X 10--2qhq”v k_—d2Ap’ v

(4)

where

v is the dynamic viscosity, in pascal sec-

onds, of the gas passed through the testpiece at the temperature of the test;

h is the height, in millimetres, of the testpiece;

d is the diameter, in millimetres, of the testpiece:

Ap’ is the pressure difference across the testpiece, in millimetres, of water columnz~;

q’v is the rate of flow, in cubic centimetresper minute, of gas through the test piece;

kv is a correction factor (see table 1) for the

removal of water vapour [used only if theair flow was measured by displa~ementof water).

8.S If the alternative test piece size and holder isused (see 6.1 and 5.1.2), equation (4) will be modi-fied as follows:

.4 x 106 106

— is replaced by—ndz X2

where x is the side, in millimetres, of a cubic testpiece. Equation (4) becomes

1,70 X 10- 2qhq:vkv

x2Ap’

Table 1 – Dynamic viscosity of air

Temperature Dynamic viscosityk,

‘c x 10-6 Pas

16 t7,88 0,982

18 17,98 0,980

20 18,08 0,911

22 18,18 0,914

24 18,28 0,971

4

I . . . . . ....” .,.._.—

IS 1528( Part22) :2007ISO 8841:1991

Table 2 – Dynamic viscositv of nitrogen

Tempe-rature

“c

10

11

12

13

14

15

16

17

18

19

20

21

22

Dynamicviscosity

x 10””E Pas

17,1

17,2

17,2

17,3

17,3

17,4

17,4

17,5

17,5

17,6

17,6

17,7

17,7

Tempe-rature

‘c

23

24

25

26

27

28

29

30

31

32

33

34

35

Dynamicviscosity

x 10” s Pas

17,7

17,8

17,8

17,9

19,9

16,0

18,0

18,1

18,1

18,2

18,2

18,2

18,3

9 Test report

The test report shall include the following infor-mation:

a)

b)

c)

d)

e)

f)

9)

h)

i)

the name of the testing establishment;

the date of the test;

a reference to this International Standard, i.e.“Determined in accordance with ISO 8841”;

a description of the material tested (manufac-turer, type, batch number, etc.);

the number of samples tested for each directionof gas flow in the brick or item;

[he gas used;

the separate pressure drops (pressure or

suction) across the test piece, and the corre-sponding rate of gas flow through the test piece;

the mean value of the permeability of the ma-terial for each direction of gas flow (relative tothe direction of pressing of the brick or item);

Preference to any variation in permeability be-

tween the three different determinations which isgreater than the permitted value (see 7.4 and7.5).

NOTE 10 The individual values are used for determiningthe mean value. The mean value is used for further stat-istical analysis, in accordance with the ISO 5022.

5“

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This Indian Standard has been developed from Dot: No. MTD 15 (4710).

Amendments Issued Since Publication

Amendment No. Date of Issue Text Affected

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