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IS 15209 (2002): Work-Place Air - Determination of MassConcentration of Nitrogen Dioxide - Method Using DetectorTubes for Short-Term Sampling with Direct Indication [CHD32: Environmental Protection and Waste Management]

IS 15209:2002ISO 8761 :1989

I\ WORK-PLACE AIR — DETERMINATION OF MASS

CONCENTRATION OF NITROGEN DIOXIDE —METHOD USING DETECTOR TUBES FOR SHORT-

TERM SAMPLING WITH DIRECT INDICATION

I

Ics 13.040,30

.

@ BIS 2002

BUREAU OF INDIAN STANDARDSMANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MAI?G

NEW DELHI 110002

.September 2002 Price Group 4

I

Environment Protection and Waste Management Sectional Committee, CHD 32

NATIONAL FOREWORD

This Indian Standard which is identical with ISO 8761:1989 ‘Work-place air — Determination of mass

concentration of nitrogen dioxide — Method using detector tubes for short-term sampling with direct

indication’ issued by the International Organization for Standardization (ISO) was adopted by the Bureau

of Indian Standards on the recommendations of Environment Protection and Waste Management Sectional

Committee and approval of the Chemical Division Council.

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

deviations. 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 should be

read as ‘Indian Standard’. ..

f

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

q

CROSS REFERENCE(.

In this adopted standard, ISO 6879:1983 ‘Air quality — Performance characteristics and related concepts

for air quality measuring methods’ has been referred, against which there is no Indian Standard.

For tropical countries like India, the standard temperature and the relative humidity shall be taken as27 i 20C and 65* 5 percent respectively.

For the purpose of deciding whether a particular requirement of this standard is complied with, the final

value, observed or calculated, expressing the result of a test or analysis, shall be rounded off in accordance

with IS 2:1960 ‘R~les for rounding off numerical values (revLse~.’The number of significant places retained

in the rounded off value should be the same as that of the specified value in this standard.

i

.*

IS 15209:2002

ISO 8761 :1989

Indian Standard

WORK-PLACE AIR — DETERMINATION OF MASSCONCENTRATION OF NITROGEN DIOXIDE —

METHOD USING DETECTOR TUBES FOR SHORT-TERM SAMPLING WITH DIRECT INDICATION

4 Scope

This International Standard specifies a method forthe determination of the mass concentration of ni-trogen dioxide present in the air at work places(work areas or stationary posts) within the range ofapproximately, 1 mg/ms to 50 mg/ms using detectortubes

Substances which, if contained in the air mass underinvestigation and thus in the air sample, are knownto have an effect on the instrument reading, are in-dicated in clause 5. Information on performancecharacteristics is given in 9,2; in applications re-quiring better precision or freedom from interfer-ences, the use of classical chemical or instrumentalmethods is recommended.

The method is suitable for personal, breathing-zonesampling as well as for the general area sampling,

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 687!9:1983, Air quality – Performance character-istics and related concepts for air quality measuringmethods,

3 Definitions

For the purposes of this International Standard, thefollowing definitions apply.

3.1 length-of-stain detector tube: A tube containinga reagent which reacts rapidly with nitrogen dioxidepresent in the air sample, producing a sharply de-fined interface between reacted and unreacted rea-gent system.

3,2 voiume per stroke: The amount of air or othergas mixture drawn by the detector-tube pump duringthe opening time per stroke.

3.3 opening time per stroke: The time taken for onecomplete cycle of the detector-tube pump air cham-ber.

4 Prlnclple

Reaction of nitrogen dioxide present in the air sam-ple passing through a detector tube within a givenperiod with reagents coated on a solid support con-tained in the tube, Fesulting in the formation of acoloured reaction product which provides a sharplydefined stain in the tube.

Determination of the mass concentration of nitrogendioxide by comparing the observed length of staindeveloped to lengths of stain prepared using cali-bration gas mixtures, taking into account the effectof interferents on the instrument reading and thecorrection factors for pressure. temperature andrelative humidity.

5 Reactions and interferents

Several colour-producing ~eactions by which nitro-gen dioxide can be detected are known. The follow-ing are used in detector tubes.

1

IS 15209:2002

ISO 8761 :1989

5.1 N, Af’-diphenylbenzldine reaction

Tubes containing a reagent system based onN, N’-diphenyl-benzidine are length-of-stain detectortubes; the change of inteqsity of colour is from greyto blue-grey.

5,1.1 Reaction equation

NOz+C6H~–NH–CeHd–C8 Hd–NH–CeH~ + colouredcompounds

5.1.2 Interferents

Chlorine and ozone produce stains similar to thoseproduced by nitrogen dioxide, but with lower sensi-tivity. For example, at the mass concentration ofchlorine of 3 mg/ms, a length of stain correspondingto the length of stain at the mass concentration ofnitrogen dioxide of 0,8 mg/ms is produced; at themass concentration of chlorine of 6 mf$rns, a lengthof stain corresponding to the length of stain at themass concentration of nitrogen dioxide of1,6 mg/ms is produced; and at the mass concen-tration of ozone of 2 mg/ms, a length of stain corre-sponding to the length of stain at the massconcentration of nitrogen dioxide of 0,4 mg/ms isproduced.

5.2 N-(1- naphthyl)-ethylenedlaminedihydrochloride reaction

Tubes containing a reagent system based onN-(1 -naphthyl)-ethy lenecfiamine dihydrochloride arelength-of-stain detector tubes; the change of inten-sity of colour is from white to red.

5.2.1 Reaction equation

N02+CIOH7-NH-CH2 -–CH2–NH2, 2HCI++H2N–C6H4–S03H ~ diazo complex

5.2.2 Interferents

Chlorine and ozone are positive interferents.

5.3 o-Toiidine reaction

Tubes containing a reagent system based ono-tolidine are length-of-stain detector tubes; thechange of intensity of colour is from white toyellow-orange.

5.3.? Reaction equation

NOz+NH2(CHJCGHq-CGHJCHJNH2 ~ colouredcompounds

5.3.2 Interferents

Halogens and chlorine dioxide and most otheroxidizing agents produce stains similar to thatproduced by nitrogen dioxide. Sulfur dioxide at massconcentrations greater than 100 mg/rns bleach thestain produced by nitrogen dioxide.

6 Apparatus

A complete measurement system consists of acompatible detector tube and detector-tube pump.These systems are normally calibrated and suppliedby the same manufacturer.

6,1 Detector tubes, containing a reagent that iscoated on a solid support and is suitable for acolour-producing reaction by which the mass con-centration of nitrogen dioxide present in the air atwork places (work areas or stationa~ posts) can bedetermined, with measuring range approximately1 mg/ms to greater than 50 mg/ms, within the ac-ceptable ranges of temperature, pressure and rela-tive humidity stated by the manufacturer.

Use only detector tubes which

a) are uniformly packed, i.e. uniform packingtightness with no obvious segregation;

b) contain filling layers, the surfaces of which areperpendicular to the tube axis;

c) are free from leaks;

and, in addition, meet the following requirement:

d) length-of-stain detector tubes shall be designedto have an inaccuracy of less than & 25 ‘A anda length of stain of at least 15 mm at the appli-cable maximum permissible value, for exampleThreshold Limit Value (TLV) of the mass con-centration of nitrogen dioxide.

Store the detector tubes in accordance with themanufacturer’s instructions.

WARNING – Detector tubes not used within the sta-bility period of the reagent system stated by themanufacturer shall be discarded (see 8.3).

6,2 Detector-tube pump, hand-operated or battery-powered.

Use only the detector-tube pump specified for usewith the detector tube, which has a volume perstroke not differing by more than t 5 0/0 from thenominal volume per stroke, which is free from leaks,and which, when operated, gives the volume flowrate referred to in the calibration of the detectortube.

2

IS 15209:2002ISO 8761 :1989

Handle the detector-tube pump carefully and main-tain it according to the manufacturer’s instructions.Test the detector-tube pump as specified in 8.1.

NOTE 1 The intensity-of-colour development in the de-tector tube is a function of volume flow rate as well as ofthe total volume of air or other gas mixture passedthrough the detector tube at a given mass concentrationof nitrogen dioxide. The volume flow rate depends on thesuction effect on the detector-tube pump and on the re-sistance to flow of the detector tube. The opening time perstroke of the detector-tube pump is affected by leaks ofthe detector-tube pump and particles deposited on thefilter or on the wall of the flow channel of the detector-tube pump.

7 Sampling

Test the detector-tube pump (6,2) for leaks by in-serting an unopened detector-tube 16.1) into the inletport of the detector-tube pump and then operatingthe detector-tube pump. No air should flow in thesystem. If air-flow occurs, as indicated by, for ex-ample, a movement of the detector-tube pump airchamber, leaks may be present in the detector-tubepump, and the detector-tube pump shall be exam-ined and repaired or replaced, as necessary.

Also test for flow blockage by operating thedetector-tube pump without a detector-tube. Thedetector-tube pump should operate freely. If not,examine and repair or replace the detector-tubepump.

Break off both ends of the detec~or tube and insertthe opened detector tube, with the prescribed ori-entation if applicable, into the inlet port of thedetector-tube pump. Note that the opened detectortube shall be tightly linked to the detector-tubepump.

Take, by operating the detector-tube pump at the

previously determined measurement point, an

amount of air the volume of which is prescribed bythe number of detector-tube pump strokes to bemade, in accordance with the calibration data of thedetector tube.

At the end of the sampling period, remove thedetector-tube from the detector-tube pump. Flushthe detector-tube pump with clean air to protect itfrom the corrosive action of reagents or reactionproducts which may be released from the detector-tube.

NOTE 2 If a hand-operated detector-tube pump isspecified for use with the detector tube, variations in theair volume flow rates between the individual detector-tubepump strokes should be minimized by operating thedetector-tube pump in a uniform manner, and, at the endof each detector-tube pump stroke, an adequate intervalof time for equalization of pressure within the detector-tube pump should be allowed.

8 Procedure

8.1 Test of the detector-tube pump

Evaluate at stated intervals of time, or more oflen,if there is any reason to suspect the pump perform-

ances:

a)

b)

the volume per strok~ (see 3.2) of the detector-tube pump, with a representative detector tube(6.1) in place, using a soap-bubble flowmeter thecapacity of which is at least 100 ml and which isequipped with a scale with scale intervals of0,5 ml. For this test, connect the suction port ofthe detector-tube pump hermetically to the exitport of the soap-bubble flowmeter;

(additionally, for hand-operated detector tubepumps) the opening time per stroke ( 3.3) with arepresentative detector tube (6.1) attached to thedetector-tube pump, in accordance with themanufacturer’s instructions.

Compare the measured values obtained with thecorresponding calibration data of the detector-tubepump and the detector tube. If these data do notagree within the limits statedin 6.2 the detector-tubepump shall be serviced, or reconditioned.

NOTE 3 The resistance to. flow of the detector tube andthus the opening time per str~ke differs according to thetype of detector tube used.

8.2 Determlnatlon

Immediately after completion of sampling, hold theused detector tube next to an unused detector tube(6.1) against a white background in adequate light-ing, but not in direct sunlight, and proceed as spec-ified in 8.2.1 and 8.2.2.

8.2.1 Evaluation of detector tube indication

The evalua%on of the detector tube indication shouldbe made only by a person trained and experiencedin detector tube reading.

Evaluate the length of stain obtained by comparisonwith lengths of stain associated with known concen-trations of nitrogen dioxide, usually marked on thedetector tube. Apply the following rules:

a) if the leading edge of the stain is not sharply de-fined, take the reading atthe point where slightdiscoloration can just be distinguished from thecolour of the unreacted reagent system;

b) if the leading edge of the stain is not perpendic-ular to the detector tube axis, take the mean re-sulting from the shortest and the longest lengthof stain, provided that the difference between theshortest and longest length of stain is not greater

.-

3

IS 15209:2002

ISO 8761 : 1989

than 20 % of the mean. Discard the detector tubereading in cases where this requirement is notfulfilled.

Record the concentration of nitrogen dioxide asso-ciated with the length of stain obtained.

8.2.2 Evaluation of correction factors

The length of stain obtained and intensity of colourdeveloped may be a function of temperature, pres-sure and relative humidity of air sample and mayalso be affected by substances other than nitrogendioxide present in the air sample.

In some cases, the interfering effects shall be takeninto account by applying correction factors. There-fore, evaluate, if necessary, correction factors ap-propriate for interpreting the detector tube reading,referring to, for example, correction factors suppliedby the manufacturer of the detector tube.

8.3 Disposal of detector tubes

Dispose of detector tubes with due regard to thetoxic or corrosive reagent or reaction products con-tained in the tubes, and in accordance with themanufacturer’s disposal instruction and national re-quirements.

9 Expression of results

9.1 Calculation

The concentration of nitrogen dioxide in the airsample is given by the detector tube indicationevaluated according to clause 8. This concentrationshall be given as mass concentration p (N02), ex-pressed in milligrams per cubic metre.

NOTE 4 The mass concentration of nitrogen dioxidep(NOJ, expressed in milligrams per cubic metre, is relatedto the volume concentration p(N02), expressed in partsper million (1 ml per 10~ ml), by the formula

46,0 x p X 293,2P(NOZ) = 2405 x (O + 273,2) x 101,3 x q(N02)

5,536 X p.

0 + 273,2x w(NOJ

where

P

o

46,0

24,05

is the pressure, in kilopascals, of the airsample;

is the temperature, in degrees Celsius, of theair sample;

is the molar mass, in grams per mole, of ni-trogen dioxide;

is the molar volume, in Iitres per mole, of anideal gas at 293,2 K and 101,3 kPa.

At 293,2 K and 101,3 kPa, the conversion factors for ni-trogen dioxide are

1 ppm - t ,91 mglma

1 mg/ms - 0,52 ppm

9.2 Precision

Relative errors in detector tube measurements aregreater at the lower end of the measuring rangethan at the higher end. The maximum permissiblerandom error, expressed as twice the relativestandard deviation (coefficient of variation) of de-tector tube measurements specified, in this interna-tional Standard is + 25 O/. at the mass concentrationlevel of nitrogen dioxide of 6 mg/ms. Some of themajor sources of variation in detector tube meas-urements are:

a)

b)

c)

variability of the internal diameter of the glasstubes; for example, a tolerance of ~ 0,1 mm is a+ 4 % variation in a 5 mm internal diameter de-~ctor tube;

variability of the tilling layer containing the rea-gent system for the colour-producing reaction;important parameters are, for example; purityand uniformity of distribution of the reagent sys-tem, uniformity of particle size and bulk densityof the solid substrate, and alignment of the fillinglayer in the detector tube;

variability of the air volume and air volumerate due to the flow characteristics ofdetector-tube pump.

10 Test report

flowthe

The test report shall include af least the followinginformation:

a)

b)

c)

d)

e)

9

9)

identification data for the air sample;

reference to this International Standard;

location in which the air sample was taken andwhether personal or general area;

identification of the manufacturer of the detectortube and detector-tube pump used, the man-ufacturer’s detector tube batch number, and thedetector tube expiry date;

stad”time and end time of the sampling period;

number of detector-tube pump strokes or volumeof the air sample;

temperature, pressure and relative humidity ofthe air sample;

4

IS 15209:2002

ISO 8761 :1989

h) interferents known or suspected to be present in j) name of the person who performed the meas-the air sample; urement.

i) mass concentration of nitrogen dioxide, ex- The test report shall also contain, if available, the

pressed in milligrams per cubic metre,,as deter- mass concentration of nitrogen dioxide, expressed

mined by the measurement with the” detector in milligrams per cubic metre, as determined by a

tube; method other than measurements with detectortubes.

-----

5

IS 15209:2002

ISO 8761 :1989

Annex A(normative)

Calibration of detector tubes

Detector tubes suitable for the determination of the‘concentration of nitrogen dioxide present in the airat work places (work areas or stationary posts) ascommercially available and specified in 6.1 havebeen calibrated by the manufacturer of the detectortubes using calibration gas mixtures. These shall bemixtures of nitrogen dioxide and a complimentarygas (e.g. purified air or nitrogen). The compositionof these mixtures shall be known within specifiedlimits. At the request of the user, the manufacturerof the detector tubes shall supply the calibrationdata for the detector tubes. Therefore, recalibrationof detector tubes is required only in exceptionalcases.

Recalibration of detector tubes can be carried outby the user of the detector tubes provided that stafftrained and experienced in preparing calibration gasmixtures are available. Some remarks on carryingout the calibration of detector tubes specified in 6.1are given below.

Prepare calibration gas mixtures following one ofthe dynamic methods listed in annex B or; prefera-bly, by the use of permeation tubes in a dynamic gasflow mixing system. Prepare a zero gas and severalgas mixtures at different concentration levels of ni-trogen dioxide within the accuracy of ~ 5 O/. cover-ing the working range, for example 2 mg/ms,4 mg/ms, 6 mg/ms, 10 mg/ms, 20 mg/m9, 30 mg/msand 50 mg/ms.

NOTE 5 The concentration of nitrogen dioxide in the gasmixture generated should be independently verified by,for example a chemiluminescence method.

At each of the selected concentration levels, take atleast five samples as follows:

Test the detector-tube pump (6.2) for leaks. by in-serting an unopened detector tube (6.1) into the inletport of the detector-tube pump and then operatingthe detector-tube pump. No air should flow in thesystem. If air-flow occurs, as indicated by, for ex-ample, a movement of the detector-tube pump airchamber, leaks may be present in the detector-tubepump, and the detector-tube pump shall be exam-ined and repaired or replaced, as necessary, Alsotest for flow blockage by operating the detector-tubepump without a detector tube. The detector-tube

pump should operate freely. If not, examine and re-pair or replace the detector-tube pump. Break offboth ends of the detector tube and connect theopened detector tube, with the prescribed orien-tation if applicable, to the device used for generati~gthe calibration gas mixture by a butt-to-butt glassjoint with, for example, a polyvinyl chloride con-nection. Insert the free end of the detector tube intothe inlet port of the detector-tube pump. Note thatthe detector tube shall be tightly linked to thedetector-tube pump and proceed as specified inclause 7.

Immediately after completion of sampling, hold thedetector tube next to an unused detector tube (6.1)against a white background in adequate lighting, butnot in direct sunlight, and proceed as specified in8.2.1.

For length-of-stain detector tubes, prepare a cali-bration graph by plotting the length of stain ob-served in the tube versus the mass concentrationp(NOJ, expressed in milligrams per cubic metre, orvolume concentration q(N02), expressed in partsper million, of nitrogen dioxide present in the cali-bration gas mixtures.

Record the volume of gas mixture passed throughthe detector tube, as well as the sampling period.

Evaluate the range of values of temperature and therange of values of relative humidity for which thecalibration graph (see ISO 6879) is valid and, in ad-dition, evaluate calibration graphs for further valuesof temperature and relative humidity. Proceed asspecified above.

NOTE 6 The calibration graphs should be valid for gasmixtures having a temperature of between 18 ‘C and30 “C and a relative humidity of approximately 50 O/..

Evaluate the repeatability within the laboratory of thedetector tube measurements at, for example, massconcentrations of nitrogen dioxide of 2 rng/ms,4 mg/m9, 6 mg/ms, 10 mg/ms, 20 mg/ms, 30 mg/msand 50 mg/ms, using the results of at least five de-tector tube determinations at each of the selectedconcentration levels.

6

IS 15209:2002ISO 8761 :1989

Determine substances which are potential NOTE 7 In cases where the effects of interferents caninterferents in the use of detector tubes (see 5.1.2, be reduced or eliminated by connecting a pretreatment

5.2.2 and 5.3.2). Evaluate their effects on the detector tube containing a suitable reagent coated on a solid sup-

tube reading as specified above and record them. port in series with the detector tube, corresponding cali-bration graphs for the detector tube and the pretreatmenttube shall be prepared.

7

---

“,>

IS 1!5209 :2002

ISO 8761 :1989

Annex B(informative)

Bibliography

[1] ISO 4226:1980, Air quality – General aspects– Units of measurement.

[2] !S06141:1984, Gasana/ysis –Ca/ibration gasmixtures—Certificate ofmixture preparation.

[3] 1S06143:1981, Gas analysis – Determinationof composition of calibration gas mixtures —Comparison methods.

[4] ISCI 6145:1986, Gas analysis – Preparation ofcalibration gas mixtures — Dynamic volumetricmethods.

[5] ISO 6349:1979, Gas ana/ysis – Preparation ofcalibration gas mixtures – Permeationmethod.

[6] ISO 6712:1982, Gas analysis – Sampling andtransfer equipment for gases supplying an an-alytical unit.

[7] ISO 7395:1984, Gas ana/ysis – Preparation ofcalibration gas mixtures — Mass dynamicmethod.

----

8

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This Indian Standard has been developed from DOC : No. CHD 32 (1002).

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Amend No. Date of Issue Text Affected

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