KENYA STANDARD DKS 648: 2009

Industrial Acetylene gas— Specification PUBLIC REVIEW DRAFT DECEMBER 2009 ©KEBS 2009 Second Edition 2009

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TECHNICAL COMMITTEE REPRESENTATION The following organizations were represented on the Technical Committee: Consumer Information Network BOC Kenya Ltd Noble Gases International Ltd Chemigas Ltd Synergy Gases Ltd Government Chemist’s Department Kenya Industrial Research and Development Institute (KIRDI) Kenyatta University, Chemistry Dept Kenya Science Teachers College Ministry of Roads and Public Works – Materials Branch Kenya Industrial Estates Kenya Medical Association Kenyatta National Hospital Ministry of Medical Sevices Kenya Bureau of Standards — Secretariat

REVISION OF KENYA STANDARDS In order to keep abreast of progress in industry, Kenya Standards shall be regularly reviewed. Suggestions for improvements to published standards, addressed to the Managing Director, Kenya Bureau of Standards, are welcome.

© Kenya Bureau of Standards, 2009 Copyright. Users are reminded that by virtue of section 6 of the Copyright Act, Cap. 130 of the Laws of Kenya, copyright subsists in all Kenya Standards and except as provided under section 7 of this Act, no Kenya Standard produced by Kenya Bureau of Standards may be reproduced, stored in a retrieval system in any form or transmitted by any means without prior permission in writing from the Managing Director.

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KENYA STANDARD

Industrial Acetylene gas— Specification

KENYA BUREAU OF STANDARDS (KEBS)

Head Office: P.O. Box 54974, Nairobi-00200, Tel.: (+254 020) 605490, 602350, Fax: (+254 020) 604031 E-Mail: info@kebs.org, Web:http://www.kebs.org

Coast Region Lake Region Rift Valley Reg ion

P.O. Box 99376, Mombasa-80100 P.O. Box 2949, Kisumu-40100 P.O. Box 2138, Nakuru-20100

Tel.: (+254 041) 229563, 230939/40 Tel.: (+254 057) 23549, 22396 Tel.: (+254 051) 210553, 210555

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Forward

This standard has been prepared by the Technical Committee on Gases under the guidance of the Standards Projects Committee, and it is in accordance with the procedures of the Kenya Bureau of Standards. Industrial acetylene covered in this standard is intended for use in the industrial sector in technical applications such as cutting, welding and illumination. The standard was first published in 1988. In this second edition purity requirement has been included. The test method for impurities insoluble in acetone has also been revised to exclude the use of mercury as a reagent. Marking requirement has also been revised to include precautionary labels, filling pressure and net weight of the contents. In the preparation of this standard, assistance was obtained from the following publications: MS167: 1973 Specification for acetylene, dissolved (technical grade). IS 308: 1988 Specification for dissolved acetylene (gas). BS 6061: 1981 Specification for transportable acetylene containers. This assistance is hereby acknowledged.

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Industrial Acetylene gas— Specification

1. Scope This Kenya Standard prescribes the requirements and methods of test for dissolved industrial acetylene gas. 2 Normative reference The following standard contains provisions which, through reference in this text, constitute provisions of this Kenya Standard. For undated reference, the latest edition of the normative document referred to applies. KS ISO 7225, Gas cylinders — Precautionary labels KS 09-532, Specification for standard atmospheric conditions for test purposes KS 647, Industrial Oxygen— Specification

3 Terms and Definitions For the purposes of this Standard the following terms and definitions shall apply.

3.1 STP standard atmospheric temperature and pressure as per KS 09-532 2. Requirements 2.1 Description The gas consists essentially of acetylene dissolved in acetone or any other solvent which shall be contained in a homogeneous porous substance which is packed in a cylinder, so that it is not deemed explosive within the meaning of the Kenya Explosives Act, Cap. 243. 2.2 Purity When tested in accordance with the method specified in Clause A3.4 of annex A the product shall have a minimum of 98 % v/v Acetylene content. 2.2 Qualitative Test The gas shall conform to the qualitative test prescribed in Clause A2 of annex A. 2.3 Impurities The product shall comply with the impurities limits given table 1.

KENYA STANDARD DKS 648: 2009

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Table 1 - Impurity limits for Dissolved Acetylene Gas SL NO. Characteristic Requirement Method Of Test

(Ref. To Clause In Annex A).

(i) Total impurities insoluble in acetone, % v/v, Max. 2.0 Clause A3 (ii) Sulphur compound (as H2S), % v/v, max. 0.02 Clause A4 (iii) Phosphorus compounds (as PH3), % v/v max. 0.01 Clause A5 (iv) Moisture, per cent by mass, max. 0.25 Clause A6 (v) Chloro-compounds To pass the test Clause A7 (vi) Carbon dioxide, % v/v max. 0.050 Clause A8 (vii) Ammonium compounds (as NH3), % v/v max. 0.050 Clause A9

3. Packaging and Marking

3.1 Packaging Dissolved acetylene shall be compressed into cylinders complying with relevant Kenya standards. Valves or taps shall not be lubricated with oil or grease.

3.2 Marking 3.2.1 Cylinder Each cylinder shall be clearly and indelibly marked with the following information: a) The words “ Industrial acetylene”;

b) The name or registered trade mark and address of the manufacturer; c) Purity; d) The impurities limits in table 1, as applicable; e) Batch number; f) Date of filling; g) Filling pressure (at STP). 3.2.2 Colour and chemical formula

Each cylinder shall in addition to the markings in 3.2.1, be painted with the colour maroon and clearly and indelibly marked with the chemical formula corresponding to acetylene.

3.2.3 Precautionary labels Each cylinder shall in addition to the markings in 3.2.1, be clearly and indelibly marked with precautionary labels as specified in KS ISO 7225.

4. Sampling 4.1 Samples shall be drawn either from the filling rack during the time the cylinders are being filled or from

cylinders after blowing off about 15 per cent of the gas contained in them. 4.2 The material shall be considered to be conforming to the standard only if both the samples comply with all

the prescribed requirements.

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Annex A

Analysis of Dissolved Acetylene Gas A1. Quality of Reagents A1.1 Unless specified otherwise, pure chemicals and distilled water shall be employed in tests.

NOTE: ‘Pure chemicals’ shall mean chemicals that do not contain impurities which affect the results of analysis.

A2. Qualitative Test A2.1 Reagent A2.1.1Silver Nitrate Solution — 0.1 per cent (m/v). A2.2 Apparatus — Funnel with clamp, as shown in Figure 1.

All dimensions in millimetres.

FIG. 1 — FUNNEL ASSEMBLY A2.3 Procedure — Place a piece of white filter paper saturated with silver nitrate solution over the mouth of

the funnel and secure with the clamp.

Fit a regulator to the cylinder and purge it for about 2 min. Attach the Tygon tubing from the regulator of the acetylene tank to the funnel tip. Set the regulator gauge pressure at not more than 0.2 kgf/cm2. Release the needle valve for 30 s, If the silver nitrate paper turns dark brown or black, the gas shall be considered to have failed the test.

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A2.3.1 The filter paper shall be used immediately after saturation. It shall not be allowed to dry, otherwise the test shall be void.

A3. Determination of Total Impurities Insoluble In Acet one A3.1 Apparatus — Assemble the apparatus as shown in Figure 2.

All dimensions in millimetres.

FIG. 2. — ASSEMBLY OF APPARATUS FOR DETERMINATION OF TOTAL IMPURITIES INSOLUBLE IN ACETONE

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A3.2 Reagent A3.2.1 Acetone A3.3 Procedure — Turn the three-way cock E to connect B with C, and pour acetone into D until C is

completely filled and D is about one-third filled. Turn E to connect B with F. Pour water into A, and fill B by raising A until water emerges from tube F. Turn E through 90 0, and then turn it to connect B with C. Lower A to draw up acetone to E. Again turn the cock through 90 0, and then turn it to connect B with F. Raise A until water emerges from E and turn the cock to horizontal position. Attach a thermometer to the apparatus. Now connect the gas sample reservoir to E, turn the cock E to connect B with E and then lower A to draw the gas into B. Collect a sufficient amount of the gas in B and turn the cock E to horizontal position. Allow the water in B to drain for 30 s. Bring the water in A and B to the same level.

The level of water in B should be at 100 ml mark if the exact amount of gas required has been taken. If the level is not at 100 ml, adjust the intake of the gas in B in such a manner as to ensure that the levels of water in B and A are brought simultaneously to the 100 ml mark. Turn E through 90 0, and turn it again to connect B with C. Pass over water from A through B right to the end of the capillary tube at the top of C and set the cock E to horizontal position. Shake the apparatus until the absorption of the gas by acetone is complete. Lower A, turn E to connect B with C and draw the unabsorbed gas back into B. Turn the cock E to the horizontal position as soon as the acetone column from C reaches E. Allow the water in B to drain for 30 s. Bring the water in A and B to the same level and note the reading on the scale and the temperature on the attached thermometer. Record the temperature in 0C from the thermometer. Fresh acetone should be taken after ten determinations. Record the percentage of the impurity as indicated by the unabsorbed portion of the gas in the capillary vessel B.

Report the corrected percentage of impurities form table A.1.

A3.4. Determination of Acetylene purity A3.4.1 Procedure A3.4.1.1 Carry out the tests as outlined in A3.3. A3.4.1.2 Determine corrected the percentage of impurities insoluble in acetone as outlined in A3.3. A3.4.1.3 Compute acetylene purity as follows: Acetylene Content % v/v= (100 –T) T = The corrected percentage of the impurity insoluble in acetone determined as described in A3.

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Table A.1 Impurities insoluble in acetone Correctio n table

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A4. Determination Of Sulphur Compounds A4.1 Apparatus A4.1.1 Gas Meter— Accurate to one per cent. A4.1.2 Gas Scrubbers — Two, of suitable design, preferably as shown in Figure 3.

All dimensions in millimetres.

FIG. 3 – DETAILS OF GAS SCRUBBERS

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A4.2 Reagents A4.2.1 Sodium Hypochlorite Solution — Containing 3 to 3.5 per cent of available chlorine. The solution shall be

saturated with sodium bicarbonate in excess. A4.2.2 Concentrated Hydrochloric Acid A4.2.3 Barium Chloride Solution — Approximately 10 per cent (m/v). A4.3 Procedure — Transfer 25 ml of sodium hypochlorite solution into each of the two scrubbers, and pass a

known volume (approximately 10 L to 15 L) of gas (see A4.3.1) at the rate of 2L/h. Note the barometric pressure and temperature. Transfer the solution in the gas scrubbers into a 100 mL beaker, wash the scrubbers with water into the beaker and boil to remove acetylene. Divide the hypochlorite solution into two equal parts and preserve one of the parts for the determination of phosphorus compounds as in Clause A5. Acidify the other part with concentrated hydrochloric acid, evaporate to dryness and bake the residue for 1 h. Allow to cool. Add 60 mL to 80 mL of hot water and 2 mL of concentrated hydrochlorite acid and heat to boiling. Filter the hot solution through a filter paper (Whatman No. 41 or equivalent), washing the residue with the hot water till the combined volume of the filtrate is about 125 m. Heat the solution and to the hot solution add a slight excess of hot barium chloride solution. Digest the precipitate for 15 min and allow the contents of the beaker to stand for 4 h. Filter the precipitate through a tared Gooch crucible or sintered glass crucible (G No. 4) and wash the precipitate with hot water till it is free from chlorides. Dry the crucible with its contents to constants mass at 105 0C to 110 0C.

Carry out a blank determination, without the gas and with another 25 mL of sodium hypochlorite solution and the same quantities of other reagents. Find the mass of the precipitate, if any.

A4.3.1 Special precaution shall be taken when treating the gas with sodium hypochlorite solution as there is a

possibility of the formation of explosive nitrogen trichloride from traces of ammonia that might be present in the gas.

A4.3.2 Excess of barium chloride is necessary to reduce the solubility of barium sulphate. Precipitation in hot

solution by addition of barium chloride in a slow stream with stirring minimizes mechanical occlusion of barium chloride and gives a coarse precipitate which is less soluble in acids.

A4.4 Calculation — Convert in litres the volume of gas taken for the test to that at normal temperature and

pressure (NTP). From the mass of barium sulphate, calculate the volume of sulphur compounds (as H2S) on the basis that 1 g of barium sulphate is equivalent to 0.096 litre of hydrogen sulphide at NTP, and express the result as percentage by volume, as follows:

Sulphur compounds (as H2S), per cent by volume = 19.2 V

BA −

where, A= mass in g of barium sulphate in the test with the gas sample, B= mass in g of barium sulphate in the blank, and V= volume in litres at NTP of the gas taken for the test. A5. Determination Of Phosphorus Compounds A5.1 Reagents A5.1.1 Concentrated Nitric Acid

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A5.1.2 Methyl Red Indicator — Dissolve 0.1 g of methyl red indicator in 100 mL of rectified spirit. A5.1.3 Ammonium Hydroxide — Relative density 0.92. A5.1.4 Ammonium Molybdate Solution — Dissolve 100 g of molybdic anhydride in a mixture of 1250 mL of

ammonium hydroxide and 250 mL of water. Pour the solution slowly, and with constant stirring, into a cooled moisture of 500 mL of concentrated nitric acid and 100 mL of water. Keep the final mixture in a warm place for several days or until a position heated to 40 0C deposits no yellow precipitate of ammonium phosphomolybdate. Decant the solution from any sediment and preserve in a glass-stoppered bottle.

A5.1.5 Ammonium Nitrate — Powder. A5.1.6 Ammonium Nitrate Solution — Approximately 5 per cent. A5.1.7 Methyl Orange Indicator — Dissolve 0.1 g of methyl orange in 100 mL of water. A5.1.8 Standard Sodium Hydroxide Solution — 0.1 M. A5.1.9 Standard Hydrochloride Acid — 0.1 M. A5.1.10 Phenolphthalein Indicator — Dissolve 0.1 g of phenolphthalein in 100 mL of rectified spirit. A5.2 Procedure — Acidify the solution preserved as in A4.3 with concentrated nitric acid, evaporate it to

dryness, and bake the residue for 1 h (due caution should be exercised in adding the nitric acid). Allow to cool. Add 80 mL to 100 mL of hot water and 3 mL of concentrated nitric acid and heat to boiling. Filter the hot solution through a filter paper (Whatman No. 41 or equivalent)., washing the residue with hot water. Boil the filtrate for 5 min and make neutral to methyl red by addition of ammonium hydroxide. Add 5 g of ammonium nitrate followed by 3 mL of concentrated nitric acid. Heat the solution to 70 ± 1 0C, and then run in slowly 30 mL of ammonium molybdate solution with constant stirring. Allow it to stand for 4 h at 45 ± 1 0C. Filter through a filter funnel with an ordinary 9 cm filter paper (Whatman No. 1 or equivalent) and wash the precipitate with ammonium nitrate solution until the filtrate is not acid to methyl orange indicator. Now transfer the precipitate together with the filter paper into the flask in which the precipitation was carried out and dissolve the precipitate by adding in excess a known volume of standard sodium hydroxide solution through the funnel in which the filtration was carried out. Rinse the funnel with water into the flask. Shake the flask until yellow precipitate is dissolved and titrate against standard hydrochloric acid using phenolphthalein as indicator. Carry out a blank determination, without using the gas and with another 25 mL of the sodium hypochlorite solution and the same quantities of the reagents. Find the volume of standard sodium hydroxide solution used.

A5.3 Calculation — Calculate the volume of phosphorus compounds (as PH3) on the basis that 1 mL of

molar standard sodium hydroxide solution is equivalent to 0.000 97 litre of phosphate (PH3) at NTP, as follows:

Phosphorus compounds (as PH3), per cent by volume

( )V

MBA −= 0.194

where,

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A= volume in mL of standard sodium hydroxide solution used in the test with the gas sample,

B= volume in mL of standard sodium hydroxide solution used in the blank,

M= molarity of standard sodium hydroxide solution, and

V= volume in litres at NTP of the gas taken for the test as in A4.3.

A6. Determination Of Moisture A6.1 Apparatus A6.1.1 Gas Meter — Accurate to one per cent. A6.1.2 Absorption Train — Two tared U-tubes connected in series and containing anhydrous calcium chloride. A6.1.2.1Prior to initial weighing of the U-tubes, completely displace the air contained in them by the gas to be

tested. A6.2 Procedure — Connect the inlet of the U-tubes to the gas sample reservoir. Record the meter reading,

barometric pressure and temperature. Pass the gas through the absorption train at the rate of 4 L to 5 L per hour for 5 h to 6 h. Disconnect the gas supply and again record the meter reading, barometric pressure and temperature. Remove the U-tubes and weigh.

A6.3 Calculation — Convert in litres the volume of the gas taken for the test to that at NTP, and from this calculate the mass of the gas on the basis that 22.4 L of gas are equivalent to 26.04 g of acetylene. Express the increase in mass of the U-tubes as percentage of the mass of the gas taken for the test.

A7. Test For Chloro-Compounds (For Navigational Illumin ant) A7.1 Apparatus — Assemble the apparatus as shown in Figure 4 in an airtight steel cabinet with removable

glass front. Suitable inlet and outlet pipes through the cabinet side shall be provided to allow the air stream and acetylene to be fed in and the excess of air and combustion products to be withdrawn.

A7.2 Reagents A7.2.1 Standard Silver Nitrate Solution — 0.05 M. A7.2.2 Standard Sodium Chloride Solution — Dissolve 1.649 g of sodium chloride in water and make up the

volume to 1 000 Ml. Pipette out 10 mL of the solution, dilute with water and make up the solution to 1 000 mL. One milliliter of this solution contains 0.01 mg of chloride (as CI).

A7.3 Procedure A7.3.1 In the scrubber containing silver nitrate solution acidified with nitric acid, add 16.0 mL of standard

sodium chloride solution and assemble the apparatus. Draw through the caustic soda scrubber a stream of air at the rate of about 65 L/h for 1 h. Disconnect the silver nitrate scrubber and use it as a comparison standard.

NOTE: 16.0 mL of standard sodium chloride solution is equivalent to 0.001 per cent by volume of

chloride in 5 mL of acetylene.

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All dimensions in millimetres.

FIG. 4 – ASSEMBLY OF APPARATUS FOR TESTING OF CHLORO-COMPOUNDS

A7.3.2 Replace in the assembly of apparatus another silver nitrate scrubber. Connect the inlet of the apparatus

to the gas supply. Pass 5 L of the gas at the rate of about 5 L per hour to the pair of Bray burners mounted just within a glass dome. Also, simultaneously draw through the caustic soda scrubber a stream of air at the rate of about 65 L per cent into the glass dome, thus providing air for the combustion and carrying on the products of combustion through the silver nitrate scrubber.

A7.4 The gas shall be considered to have passed the test if any opalescence or turbidity produced in silver

nitrate solution with the gas is not greater than that produced in the comparison standard as in A7.3.1.

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A8. Determination of Carbon Dioxide

This shall be carried out according to KS 647, Specification for industrial oxygen.

A9. Determination Of Ammonium Compounds A9.1 Known amount, X, of acetylene gas is passed through dilute sodium hydroxide and excess amount X1 of

dilute hydrochloric acid is added and titrated with dilute sodium hydroxide, X2.

Percentage ammonia is given as X

XX 100 x 21 −