SIST EN 24260:1998
(Main)Petroleum products and hydrocarbons - Determination of sulfur content - Wickbold combustion method (ISO 4260:1987)
Petroleum products and hydrocarbons - Determination of sulfur content - Wickbold combustion method (ISO 4260:1987)
The procedure specified may be applied to products having contents in the range 1 to 1O OOO mg/kg and is particularly suitable for distillates with less than 3OO mg/kg. Test samples which are viscous, highly aromatic, or of high content may be first diluted with a sulfur-free solvent. The procedure can be used for natural and refinery gases, also for substances supplied to the burner in the liquid state and for the determination of volatile sulfur in substances supplied to the burner in the gaseous state after vaporisation from the liquid phase. It is not suitable for heavy-duty engine oils.
Mineralölerzeugnisse und Kohlenwasserstoffe - Bestimmung des Schwefelgehaltes - Verbrennung nach Wickbold (ISO 4260:1987)
Diese Internationale Norm beschreibt ein Verfahren für die Bestimmung des Gesamtschwefels in Mineralölerzeugnissen, Erdgas und Ölfinen. Das Verfahren darf bei Erzugnissen mit Schwefelgehalten zwischn 1 und 10 000mg/kg angewandt werden und ist besonders geeignet für Destillate mit Gesamtschwefelgehalten von weniger als 300mg/kg. Zähflüssige und hocharomatische Proben oder solche mit einem hohen Schwefelgehalt dürfen zuerst mit einem Lösemittel verdünnt werden.
Produits pétroliers et hydrocarbures - Dosage du soufre - Méthode de combustion Wickbold (ISO 4260:1987)
La présente Norme internationale spécifie une méthode de dosage du soufre total dans les produits pétroliers, le gaz naturel et les oléfines. Elle est applicable aux produits ayant des teneurs en soufre allant de 1 à 10 000 mg/kg, et convient particulièrement aux distillats dont la teneur en soufre total est inférieure à 300 mg/kg. Les prises d'essai de produits visqueux, très aromatiques, ou à haute teneur en soufre, peuvent être d'abord diluées avec un solvant exempt de soufre. La méthode peut être utilisée pour la détermination de la teneur en soufre total des gaz naturels, des gaz de raffinerie et des produits présentés à l'état liquide au brûleur. Elle peut également être utilisée pour le dosage du soufre volatil dans les produits présentés au brûleur à l'état gazeux après vaporisation de la phase liquide. Elle ne peut pas être utilisée pour la détermination de la teneur en soufre dans les huiles moteurs en service sévère. Pour la détermination de la teneur en soufre dans les
Naftni proizvodi in ogljikovodiki - Določevanje žvepla - Metoda s sežigom po Wickboldu (ISO 4260:1987)
General Information
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Mineralölerzeugnisse und Kohlenwasserstoffe - Bestimmung des Schwefelgehaltes - Verbrennung nach Wickbold (ISO 4260:1987)Produits pétroliers et hydrocarbures - Dosage du soufre - Méthode de combustion Wickbold (ISO 4260:1987)Petroleum products and hydrocarbons - Determination of sulfur content - Wickbold combustion method (ISO 4260:1987)75.080Naftni proizvodi na splošnoPetroleum products in generalICS:Ta slovenski standard je istoveten z:EN 24260:1994SIST EN 24260:1998en01-maj-1998SIST EN 24260:1998SLOVENSKI
STANDARDSIST EN 41:1975:20071DGRPHãþD
SIST EN 24260:1998
SIST EN 24260:1998
SIST EN 24260:1998
INTERNATIONAL STANDARD INTERNATIONAL ORGANIZATION FOR STANDARDIZATION ORGANISATION INTERNATIONALE DE NORMALISATION MEXAYHAPOflHAfl OPTAHM3A~Mfl l-l0 CTAHjJAPTM3A~MM Petroleum products and hydrocarbons - Determination of Sulfur content - Wickbold combustion method Produits petroliers et h ydrocarbures - Dosage du soufre - Methode de combustion Wickbold ISO 4260 First edition 1987-04-0 1 Reference number ISO 4260 : 1987 (E) SIST EN 24260:1998
Foreword ISO (the International Organization for Standardization) is a worldwide federation of national Standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Esch member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, govern- mental and non-governmental, in liaison with ISO, also take patt in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the ISO Council. They are approved in accordance with ISO procedures requiring at least 75 % approval by the member bodies voting. International Standard ISO 4260 was Petroleum products and lubrican ts. prepared by Technical Committee ISO/TC 28, Users should note that all International Standards undergo revision from time to time and that any reference made herein to any other International Standard implies its latest edition, unless othetwise stated. 0 International Organkation for Standardkation, 1987 l Printed in Switzerland SIST EN 24260:1998
INTERNATIONAL STANDARD ISO 4260 : 1987 (E) Petroleum products and hydrocarbons - Determination of Sulfur content - Wickbold combustion method CAUTION - The procedure specified in this International Standard includes the combustion of hydrogen in glass ap- paratus or stainless steel apparatus (in the case of olefins), which is potentially hazardous, and all precautions should be carefully observed. 1 Scope and field of application 2 References This International Standard specifies a method for the deter- mination of total Sulfur in Petroleum products, natura1 gas and olefins. The method may be applied to products having Sulfur contents in the range 1 to 10 000 mg/kg and is particularly suitable for distillates with total Sulfur contents of less than 300 mg/kg. Test samples which are viscous, highly aromatic, or of high Sulfur content may be first diluted with a Sulfur-free solvent. The method tan be used for the determination of the total Sulfur content of natura1 and refinery gases, also for substances supplied to the burner in the liquid state and for the determina- tion of volatile Sulfur in substances supplied to the burner in the gaseous state after vaporization from the liquid Phase. lt is not suitable for the determination of Sulfur in heavy-duty engine oils. For the determination of Sulfur in light olefins, see clause 13, special case. NOTES 1 If required, total chlorine content of Petroleum products tan be determined by the usual volumetric, gravimetric or potentiometric methods for determination of the chloride ions present in the absorp- tion Solution after combustion by this method. The inorganic bound chlorine has to be removed by water extraction Prior to the burning procedure, otherwise interference will occur. 2 When viscous or solid materials, such as bitumen or heavy fuel oils, are burnt in a combustion boat, some of the Sulfur may be bound to the ash retained in the boat. If this is the case, the Sulfur bound in the ash has to be determined in the residue. ISO 641, Laboratory glassware - lnterchangeable spherical ground joints. ISO 3170, Petroleum products - Liquid h ydrocarbons - Manual sampling . ISO 3171, Petroleum products - Liquid hydrocarbons - Au toma tic Pipeline sampling . ISO 4850, Personal e ye-protectors for welding and related techniques - Filters - Utilisa tion and transmittance re- quiremen ts. 3 Principle Gaseous or liquid test portions are passed to the oxy-hydrogen flame of a suction burner where they are burnt *with con- siderable excess of Oxygen. Viscous or solid test samples are preferably dissolved in light petroleum/toluene blend and treated as liquid test samples or may be burnt in a stream of Oxygen in a combustion boat. The resulting Sulfur oxides are converted into sulfuric acid by absorption in hydrogen peroxide Solution. Depending on the Sulfur content of the test Portion, the sulfate ions in the absorp- tion Solution are determined using the method of analysis shown in table 1 and set out in clause 9. . SIST EN 24260:1998
ISO 4260: 1987 (E) Table 1 - Relation between expected Sulfur content, mass of test Portion, and method of analysis recommended Expected Mass Sulfur in Aliquot Sulfur Sulfur of test absorption Portion in the aliquot Method of analysis recommended content portionl) Solution of absorption Portion for different levels of wiilh SI Kl Solution IJ9 Sulfur content 100 100 112 50 50 50 Ill 50 1 20 20 l/l 20 Conductimetric Turbidimetric 5 20 100 112 50 titration titration 50 250 1/5 50 (9.4 (9.3) 50 250 Ill 250 10 5 50 l/l 50 , Nephelometric , - IO 100 112 50 titration 20 200 112 100 (9.2) 50 500 112 250 30 5 150 112 75 10 300 112 150 20 600 112 300 50 1500 1/5 300 50 5 250 112 125 Visual 10 500 112 250 titration 30 1500 1/5 300 (9.1) 100 2 200 112 100 5 500 112 250 10 1 000 115 200 1000 1 1000 115 200 2 2000 1/5 400 IO ooo 1 10 000 l/lO . 1000 I 1) The volume of a gas test Sample required may be calculated with sufficient accuracy from the mass and density of the gas. The precision data in l clause 12 do not apply for gas test samples. 4 Reagents and materials During the analysis, unless otherwise specified, use only reagents of recognized analytical grade and only distilled water or water of equivalent purity. Volumetric solutions and other reagents as specified in clause 9 under the individual method of analysis and 4.1 Hydrogen Peroxide, 3 % (mlm) Solution, free from Sulfur. 4.2 Ethanol, 96 % (V/ V), free from Sulfur. 4.3 Blend containing 4 volumes of light Petroleum, (boiling range 60 to 80 OC) and 1 volume of toluene, free from Sulfur (in the following text referred to as “light petroleum/toluene blend”). 4.4 Oxygen, compressed gas, commercial grade, free from Sulfur. 4.5 Hydrogen, compressed gas, commercial grade, free from Sulfur. 4.6 Hydrochlorit acid, concentrated, ,Ozo 1,19 g/ml. 4.7 Mercury. 4.8 Dihexyldisulfide or dibenzothiophene reference blend. Dissolve a known mass of dihexyldisulfide or dibenzothio- phene, weighed to the nearest 0,l mg, in the light petroleum/toluene blend (4.3). The concentration of the pro- duct should be Chosen from the Sulfur concentration in the range shown in column 1 of table 1 according to the finish which will be used. Dihexyldisulfide contains 27,36 % (mlm) of Sulfur, and di- benzothiophene contains 14,7 % (mlm) of Sulfur. CAUTION - lt is recommended that high-pressure gas cylinders are not stored in the laboratory. SIST EN 24260:1998
ISO 4260: 1987 IE) 5 Apparatus NOTE - In Order to provide a detailed description of the mode of Operation, this International Standard has been based on two types of burners and a Single type of absorption train. Other types of burner using the principle of combustion of a test por- tion in an oxy-hydrogen flame with excess Oxygen may be used (see clause 13). These should be operated as described in the manufac- turers’ instructions and checked by the combustion of test portions of the Standard Sulfur-containing reference blends (see clause IO). Apparatus specif ied analysis and in clause 9 under individual method of 5.1 Combustion apparatus (sec figure 1 for the schematic layout of the apparatus for the combustion of gaseous or liquid test samples and figure 2 for that for the combustion of viscous or solid test samples), consisting essentially of the following components : 5.1.1 Reducing valve (11, with gauge, range 0 to 5 bar (0 to 500 kPa)l) for Oxygen I . 5.1.2 Reducing valve (21, with gauge, range 0 to 2 bar (0 to 200 kPa), for hydrogen. 5.1.3 Flowmeter (31, range 20 to 300 I/h, operating on the floating element principle, with precision control valve, for the secondary Oxygen line. 5.1.4 Flowmeter (41, range 20 to 200 Vh, operating on the floating element principle, with precision control valve, for the hydrogen line. 5.1.5 Flowmeter (51, range 200 to 2 000 I/h, operating on the floating element principle, with precision control valve, for the primary Oxygen line. 5.1.6 Excess-pressure vessels (61, for example wash bot- tles, containing mercury (4.7) and white oil (sec 8.21, or metal pressure safety valves. Three are required. The inlet valves must be of the non-return type. 5.1.7 Flame trap (71, with metal connections. 5.1.8 Flow indicator (81, glass. 5.1.9 Vacuu’m gauge (111, range from approximately 0,6 to 1 ,l bar (60 to 1 IO kPa) absolute. 1) 2) The burner and combustion chamber as shown are claimed to be the subject of Patents in some countries. Information on the patent sh ould be sought from local suppliers. However, most of these Patents are unlikely to be still current. 1 Pa = 1 N/m* = IO-5 bar 5.1.10 Vacuum line (121, with vacuum valve (9), and branch line to vacuum gauge Ul), and a branch line with stopcock (IO) to the flow indicator (8). \ 5.1.11 Narrow-necked one-mark volumetric flask (13), 100 or 250 ml capacity, with spherical ground glass joint, ISO 641-s29115. 5.1.12 Combustion chamber2) (201, of transparent fused quartz, cooler (191, absorber tower (17), frit-type filter, pore size index 1,6 mm (161, drip chamber (15), three-way stopcock (141, and ground glass spherical joint, ISO 641-S29/15, assembled into a Single unit. The combustion chamber, cooler and absorber tower are enclosed in a water- cooled jacket. 5.1.13 Burner2) (211, of stainless steel or transparent fused quartz. The burner should be of the suction type (see figure 1) for the combustion of gaseous or liquid products. A stainless steel burner may be used as an alternative and such a burner shall be used for light olefins (sec figure 3). 5.1.14 Stopcock (181, fitted in the line connecting the ab- sorption Solution flask and absorber tower (17). . 5.1.15 Test Portion Container (22). The assembly of the combustion equipment shown in figure 1 uses a test Portion Container, for example a conical flask, approximately 100 ml capacity. (See also 8.6.1 to 8.6.4.) When testing highly volatile test samples, the conical flask should be enclosed by a vacuum jacketed vessel or other similar device. The flask is held in place by means of an adjustable support. The assembly of the combustion equipment shown in figure 2 uses a combustion boat as the test Portion Container. 5.1.16 Gas Sample meter. A dry gas meter connected to a precision type valve for measuring the quantity of test Portion for gas samples shall be used, unless this is to be determined gravimetrically. The range of the meter shall be appropriate for the quantity of Sample to be burned and the meter shall be recently calibrated. 5.1.17 Connectors. For connecting the hydrogen and oxy- gen cylinders with flowmeters (3), (41, and (51, use high- pressure metal piping. The remaining piping in the System may be made of elastomers, such as Silicone rubber. 5.1.18 Bunsen burner. 5.1.19 Analytical balance. Position 3 SIST EN 24260:1998
Cooling entry Spherica ISO 641- Absorption Solution water @ij 1 Reducing valve for Oxygen 2 Reducing valve for hydrogen 3 Flowmeter for secondary Oxygen line 4 Flowmeter for hydrogen line 5 Flowmeter for primary Oxygen line 6 Excess-pressure vessels 7 Flame trap 8 Flow indicator 9 Vacuum valve 10 Stopcock 11 Vacuum gauge 12 Vacuum line 13 Narrow-necked volumetric flask 14 Three-way stopcock for positions (a) and (b) 15 Drip chamber 16 Sintered glass filter 17 Absorber tower 18 Stopcock 19 Cooler 20 Combustion chamber 21 Suction-type burner 22 Test Portion Container 23 Stopcock - Hydrogen - Oxygen 0 1 Figure 1 - Schematic layout of apparatus for combustion of gaseous or liquid test samples m ._-_ --~~-~_.--- - - --__ _ - -. - -~ SIST EN 24260:1998
Absorption r solution \ Q 20 Cooling water exit L Q Q Cooling water entry 3 90 (c> 11 I ! II I 7 POb---c Vacuum 27 27 55 - l-4 w Ok IO V 23 Spherical 1 Reducing vaive for Oxygen 2 Reducing valve for hydrogen 3 Flowmeter for secondary Oxygen line 4 Flowmeter for hydrogen line 5 Flowmeter for primary Oxygen line 6 Excess-pressure vessels 7 Flame trap 8 Flow indicator 9 Vacuum valve 10 Stopcock 11 Vacuum gauge 12 Vacuum line 13 Narrow-necked volumetric flask 14 Three-way stopcock for positions (a) and (b) 15 Drip chamber 16 Sintered glass filter 17 Absorber tower 18 Stopcock 19 Cooler 20 Combustion chamber 21 Solid product burner 22 Test Portion Container 23 Stopcock Figure 2 - Schematic layout of apparatus for combustion of viscous or solid test samples SIST EN 24260:1998
ISO 4260: 1987 (EI 5.2 Safety appliances 8.2 Assembly of apparatus 5.2.1 A Screen, for example of safety glass, or fine-mesh wire gauze or suitable transparent plastics material or equivalent, to Screen off the burner, combustion chamber and absorber tower. 5.2.2 Protective glass filter goggles, capable of absorbing harmful radiation given off during combustion, shall be worn to protect the operator’s eyes. Oxy-acetylene welding goggles are suitable (sec ISO 4850). For testing gaseous or liquid test samples, assemble the carefully cleaned apparatus as shown in figure 1, or for viscous and solid test samples as shown in figure 2. Fill the three excess-pressure vessels (6) with the mercury (4.7) up to a level of approximately 300 mm and float approximately 20 mm of white oil on top of the mercury or adjust the safety valves to an equivalent relief pressure. Fill the flow indicator (8) with partments is about 30 mm. water until the level in both com- 52.3 Safety electrovalves, capable of shutting off the hydrogen stream : one on the cold-water circuit, which operates only in the event that admission of water Stops, and the other in the vacuum line (12) which operates only in case of Variation in the low pressure in the combustion chamber. In the assembly shown in figure 1, support the suction burner (21) with a wire or wire coil of suitable length. Ensure that the safety devices (sec 5.2) are in place. 6 Sampling Test samples shall be taken following the appropriate good practice for sampling Petroleum products. Suitable procedures for sampling from bulk storage are specified in ISO 3170 and for automatic sampling from Pipe-lines are specified in ISO 3171. For gaseous products, on-line sampling and testing is recommended. 7 Size of test Portion The size of the test Portion required depends on the Sulfur con- tent of the test Sample and on the method of analysis employed to determine the Sulfur content. The quantities of test Portion required for different combinations of Sulfur content and methods of analysis are set out in table 1. 8 Combustion procedure 8.1 Cleaning of apparatus Scrupulous cleanliness of test Portion Containers and apparatus is required throughout. Wash the test pottion Containers, lines, valves, and connectors used for gas and LPG test samples with light petroleum/toluene blend (4.3) until the Sulfur content of the washings as determined according to the procedure for liquid test samples is negligible. Ensure that the Containers are solvent-free before taking test portions. Glassware and silica- ware tan be cleaned with concentrated detergent but must finally be thoroughly washed with water to remove Sulfur com- pounds. More rigorous cleaning tan be accomplished with dichromate/nitric acid cleaning agent. Silicaware tan be clean- ed by heating in a muffle furnace. lt is preferable to reserve a set of test Portion Containers and the silica and glassware equipment for low Sulfur content test samples and to keep another set for high Sulfur content test samples. NOTE - After each combu,stion or series of combustions, the com- bustion chamber should be cleaned by washing carefully with the hydrochloric acid (4.61, diluted (1 + 11, and with water. 8.3 Preparation of apparatus Pass a rapid stream of cold water in the direction shown in figures 1 and 2, through the cooling jacket enclosing the com- bustion chamber, cooler and absorber tower. Fill the absorption Solution reservoir with the hydrogen peroxide Solution (4.1). Adjust the Oxygen pressure reducing valve (1) to 1 bar (100 kPa) and the hydrogen pressure reducing valve (2) to 05 bar (50 kPa). Ensure that the valves of meters (3), (4) and (5) are closed. Turn the three-way stopcock (14) to Position (a). Remove the burner (21) and open the stopcock (10) upstream of the flow indicator (8). Open the valve upstream of flowmeter (5) to allow an Oxygen stream of 600 to 800 I/h to pass through the primary Oxygen line, and open the valve upstream of flowmeter (3) to allow 100 to 200 I/h of Oxygen to flow through the secondary Oxygen line. Re-introduce the burner (21) and, at the same time, open the vacuum valve (9) until the flow in- dicator (8) drops back to Zero. Close the stopcock (10). Set the vacuum valve (9) so that the vacuum gauge (11) indicates a pressure of 0,135 to 0,35 bar (13,5 to 35 kPa) absolute. 8.4 Ignition of oxy-hydrogen flame 8.4.1 Suction burner (sec figure 1) Remove the suction burner (21) from the combustion chamber (20). Open the valve upstream of flowmeter (4) so that a hydrogen flow of approximately 200 I/h is admitted, (sec note 2). Allow hydrogen to flow freely for approximately 30 s before igniting the oxy-hydrogen flame with a wax taper or electrical ignition device. Matches shall not be used. CAUTION - Use safety goggles (sec 5.2.2). NOTES 1 This procedure is modified when burning certain gaseous samples (sec 8.6.1). 6 SIST EN 24260:1998
ISO 4260:1987 (El 2 When the burner is being flushed with hydrogen, care should be exercised that the hydrogen leaving the burner mouth does not pass in- to the combustion chamber, otherwise darnage may occur when the burner is lit. Replace the suction burner (21), avoiding contact between the combustion chamber joint (20) and the oxy-hydrogen flame. With the aid of the valve upstream of flowmeter (4), adjust the hydrogen flow so as to obtain an oxy-hydrogen flame length of 10 to 20 mm. This will produce a drop in pressure at the vacuum gauge (11). Readjust the vacuum to 0,135 to 0,35 bar (13,5 to 35 kPa) by means of vacuum valve (9). lt is important to maintain this vacuum level to achieve steady combustion. If it is intended to carry out a blank test on the gases the dura- tion of the combustion should be noted. 8.4.2 Solid products burner (see figure 2) Sub-clause 8.4.1 applies equally to the ignition of the oxy- hydrogen flame in the solid products burner (21). 8.5 Control of absorption Solution supply Turn the stopcock (18) so that the supply of absorption Solution is adjusted to a rate of 1 to 5 drops per second. ’ 8.6 Combustion of test Portion 8.6.1 Gaseous test samples (general) 8.6.1.1 In the general procedure, the samples are burnt in the oxy-hydrogen flame; however, samples of natura1 gas fre- quently have very low Sulfur contents (approximately 1 mg/kg) and it is necessary to burn larger test portions. For such samples, there is no need for an oxy-hydrogen flame as a back- up flame for burning the gas and these gases tan be burnt directly in the Oxygen stream as in 8.6.2. NOTE - The procedures in 8.6.1 and 8.6.2 relate to test portions taken direct from a bulk Sample or from a large Sample Container. Alterna- tively, the test Portion may be the entire contents of a suitable gas sam- ple Container; the quantity of the test Portion may then be determined by weighing the Container before and after the combustion procedure. lt is important to ensure that all of the test Portion has been transferred to the combustion chamber. 8.6.1.2 Allow the test Portion of gaseous Sample to flow from the Sample Container through a precision-type valve and a dry gas meter into the test portion supply line of the suction burner (21). A safety pressure-relief valve may be included before the gas meter. Adjust the vacuum valve (9) and stopcock (23) so that a flame approximately 3/4 of the length of the combustion chamber (20) is obtained. Care shall be taken that the flame does not extend to tauch the condenser coil. Ensure that during the combustion process the vacuum gauge (11) indicates a steady vacuum. 8.6.1.3 When a sufficient volume of the test Portion (see table 1) has been burnt, close the gas meter valve. Pinch off the connection between the gas meter and the test Portion supply line to allow any residual gas in the test portion supply line to be drawn into the suction burner (21) and burnt. Close stopcock (18) to shut off the flow of absorption solution. NOTE - If the test Portion is the contents of a gas Sample cylinder, when the test Portion is completely burnt, two portions, each of a volume corresponding to approximately 2 % of the volume of the cylinder of the light petroleum/toluene blend (4.3) should be intro- duced into the cylinder to dissolve any residual patt of the test Portion and each Portion burnt in the oxy-hydrogen flame. 8.6.1.4 Shut off the hydrogen stream by closing the valve upstream of flowmeter (4). When the burner tip is visibly free from glowing particles, shut off both Oxygen streams by clos- ing the valves upstream of the flowmeters (3) and (5) and im- mediately remove the suction burner from the combustion chamber. 8.6.1.5 Spray several jets of distilled water from a wash bottle onto the interior Walls of the combustion chamber in Order to wash any residual combustion products through the cooler and absorber tower into the narrow-necked volumetric flask (13). 8.6.1.6 Turn the three-way stopcock (14) to Position (b) to relieve the vacuum in the narrow-necked flask (13) and then remove it. Close vacuum valve (9) and open stopcock (10). NOTE - If a series of test portions is to be burnt, neither the oxy- hydrogen gas flame nor the vacuum need be shut off after combustion of each portion to prepare equipment for further combustion. After the initial test Portion has been burnt, shut off supply of absorption solu- tion, and remove the lighted burner (21) from combustion chamber (20). After spraying distilled water through the combustion chamber (sec 8.6.1.51, replace narrow-necked volumetric flask (13) by another one and re-insert the burner into the combustion chamber. 8.6.2 Gaseous test samples (low Sulfur content) 8.6.2.1 Remove the hydrogen supply line to the suction burner (21) and in its place connect the test portion supply line for the gas. This supply line shall include a precision-type valve and a dry gas meter (5.1.16) and may include a safety pressure relief valve before the meter. Prepare the apparatus as specified in 8.1 to 8.3 but do not ignite the burner as specified in 8.4. 8.6.2.2 Remove the suction burner (21) from the combustion chamber (20), allow the gaseous test Sample to flow through the precision-type valve and the dry gas meter into the burner. Keep the stopcock (23) closed. Allow the gas to flow freely for approximately 30 s before igniting the flame, use a wax taper or an electrical ignition device. Matches shall not be used. Replace the burner in the combustion chamber, avoiding contact be- tween the combustion chamber joint and the flame. Adjust the vacuum valve (9) and the precision-type valve of the gas test portion supply line so that a flame approximately 3/4 of the length of the combustion chamber (20) is obtained. Care shall be taken so that the flame does not extend to tauch the con- denser coil. Ensure that during the combustion process the vacuum gauge (11) indicates a steady vacuum. 8.6.2.3 When a sufficient volume of test Portion (see table 1) has been burnt, close the precision-type valve, pinch off the connections between the gas meter and the supply line to allow any residual gas in the supply line to be drawn to the suction 7 SIST EN 24260:1998
ISO 4260: 1987 (El burner and as much as possible burnt. With test samples having low Sulfur contents, the unburnt Portion will not be suf- rate of secondary Oxygen. Readjust the pressure at the vacuum gauge m. the liquid flow ficient to introduce significant error. shut off the flow absorption solution. Close stopcock (18) to NOTE - If the test Portion is the contents proceed as described in the note in 8.6.1.3. of a gas Sample cylinder, 8.6.2.4 When the burner tip is visibly free from glowing par- ticles, shut off both Oxygen streams by closing the valves upstream of the flowmeters (3) and (5) and immediately remove the suction burner from the combustion chamber. Proceed as in 8.6.1.5 and 8.6.1.6 (the note does not apply). 8.6.3 Liquefied Petroleum gas test samples Transfer a test Portion of the test Sample in its liquid form from its Container to a test Sample cylinder. From the latter, pass the liquid through a vaporizer coil at a temperature of 60 to 80 OC, and pass the resulting gas through the test Portion supply line to the suction burner (21). Alternatively, combustion tan be improved by reducing using the stopcock (23) in the test Portion supply line. 8.6.4.3 When the test Portion is completely burnt, introduce two portions, each of 2 ml, of the ethanol (4.2) into the test Portion Container (22) to wash down unburnt residues and burn each Portion in the oxy-hydrogen flame. To wash down higher boiling Petroleum products, use the light petroleum/toluene blend (4.3). 8.6.4.4 Shut off the hydrogen and Oxygen streams following the procedure of 8.6.1.4, and detach the flask (13). Close the vacuum valve (9) and open stopcock (10). Proceed as in 8.6.1.5 and 8.6.1.6. NOTE - 8.6.1.6. For combustion of a series of samples. see the note in 8.6.5 Leaded gasoline samples (sec the note in 12.2) Adjust the flame size as indicated in 8.6.1.2 (in this case the first Paragraph of 8.6.1.2 does not apply), readjust the Oxygen flow rate if necessary and complete the combustion (sec the note in 8.6.4.2). Proceed as in 8.6.1.3 to 8.6.1.6. 8.6.5.1 Alternative procedures If the lead content of the Sample is accurately known, the direct combustion procedure specified in 8.6.5.3 may be employed. Calculate the quantity of the test Portion used from the dif- ference between the apparent masses of the empty and full test Sample cylinder. Generally a 30 to 50 g test Portion will suffice. If, however, the amount of lead present is unknown or if it is known and the value of the term 8.6.4 Liquid test samples 32 lead concentration x - 207 Liquid Petroleum hydrocarbon fractions, up to and including light fuel Oil, may be burnt by feeding directly into the oxy- hydrogen flame. Lubricating oils free from ash-forming additives and Petroleum hydrocarbons with higher viscosities than light fuel oil may also be burnt in the assembly shown in figure 1 after dilution with the specified light petroleum/toluene blend (4.3). is significant with respect to the concentration of Sulfur sought, the use of the extraction method 8.6.5.2 is preferred. NOTE - If the procedure in 8.6.5.3 is used, lead Oxide produced during combustion may condense on the burner and result in erratic burning; in addition, traces of lead Oxide may remain in the System and will interfere with subsequent tests on lead-free samples if the Thorin method (9.1) is used. CAUTION - Liquids of volatility comparable with that of isopentane may Cause explosions. Such test samples should be blended before combustion with a high boiling solvent, for example iso-octane. 8.6.4.1 Weigh a test Portion (sec table 1) to the nearest 0,05 g into the pre-weighed Container (22). Place the Container with the test Portion on an adjustable support under the free end of the supply line to the suction burner (21). Raise the Container until the supply line reaches the bottom of the Container. 8.6.4.2 Increase the vacuum carefully with the aid of vacuum valve (9) so that the test Portion is slowly drawn into the oxy- hydrogen flame. Adjust the vacuum valve (9) until the combus- tion flame fills approximately 3/4 of the length of the combus- tion chamber (20) corresponding to a combustion rate of ap- proximately 3 to 5 ml/min. Ensure that the flame is completely smoke-free and does not extend into the condenser coil. 8.6.5.2 Gasoline of unknown lead content Introduce a test portion of approximately 100 ml and 50 ml of the hydrochloric acid Solution (4.6) into an extraction apparatus (see figure 4). To avoid any loss of volatile constituents, pass a stream of ice water through the reflux condenser. Extract for approximately 5 min from initial time of boiling. After cooling and allowing the phases to separate, draw off the hydrochloric acid layer and reject it. Wash the gasoline layer with water until the washings are neutral to methyl orange. The gasoline layer is then burnt as a liquid test Sample. NOTE - If it is intended to use the turbidimetric titration described in 9.3, the extraction step may be omitted and the test Portion burned as a liquid test Sample (sec 8.6.4). If the extraction is omitted,
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