HG/T 3666-2000 Pure rubber hose and rubber hose for conveying oxidized fuel in internal combustion engine fuel system
Some standard content:
Registration No.: 7266-2000
HG/T 3666-2000
This standard is equivalent to the international standard 1SO4639-3:1995 "Pure rubber hose and rubber hose for internal combustion engine fuel system Part 3: Oxidized fuel".
The series of standards for "Pure rubber hose and rubber hose for internal combustion engine fuel system" includes the following three standards: HG/T3042-1989 "Pure rubber hose and rubber hose for conveying conventional liquid fuel in internal combustion engine fuel system" (eqvISO4639-1:1987)
HG/T3665-2000 "Pure rubber hose and rubber hose for conveying oxygenated fuel in internal combustion engine fuel system" (idtISO4639~2:1995) HG/T3666-2000 "Pure rubber hose and rubber hose for conveying oxidized fuel in internal combustion engine fuel system" (idtISO4639-3:1995) Appendix A, Appendix B, Appendix C and Appendix D of this standard are the appendices of the standard. Appendix E is a prompt appendix. This standard was proposed by the Technical Supervision Department of the former Ministry of Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of the Hose Sub-Technical Committee of the National Technical Committee for Standardization of Rubber and Rubber Products. The responsible drafting unit of this standard: Shenyang Rubber Research and Design Institute of the former Ministry of Chemical Industry. The main drafters of this standard are Li Chunming and Zhang Jingzhi. 395
HG/T3666-2000
ISO before
ISO (International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of formulating international standards is usually carried out by ISO technical committees. Any member group interested in a project for which a technical committee has been established has the right to participate in the committee. International organizations, both governmental and non-governmental, that have ties to ISO may also participate in this work. ISO works closely with the International Electrotechnical Commission (IEC) in all aspects of electrotechnical standardization. Draft international standards adopted by the technical committee are sent to member groups for voting. When published as an international standard, at least 75% of the voting member groups must vote in favor.
International Standard ISO4639-3 was developed by Technical Committee SC1 Hose (Rubber and Plastics) of ISO/TC45 Rubber and Rubber Products Technical Committee.
ISO 4639 is titled "Specification for pure rubber tubing and hoses for fuel circuits for internal-combustion engines using oxidized fuels" and consists of the following three parts: Part 1: Conventional liquid fuels
Part 2: Oxygenated fuels
Part 3: Oxidized fuels
Appendices A, B, C and D are appendices to the standard that constitutes this part of ISO 4639. 396
1 Scope
Chemical Industry Standard of the People's Republic of China
Rubber tubing and hoses for fuel circuits for internal-Combustion engines using oxidized fuelsHG/T 3666 2000
idt ISO 4639-3:1995
This standard specifies the requirements for pure rubber tubing and hoses for use in fuel circuits where the fuel can become oxidized or "acidified". These fuels may or may not contain compounds such as ethanol. This standard does not cover pure rubber hoses used in liquid fuel dispensing equipment, nor does it apply to pure rubber hoses that are completely immersed in fuel tanks. These hoses and pure rubber hoses are used in injection systems that recirculate fuel and other systems that may be subjected to special storage at high ambient temperatures after filling. Such hoses and pure rubber hoses generally have an inner lining made of special elastomeric materials (see Figure 1). Outer layer-
Pure rubber hose
2 Referenced standards
Reinforcement layer7
Inner lining layer
Inlaid village layer
Inlaid layer
Figure 1 Typical structure diagram
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. At the time of publication of this standard, the versions shown are valid. All standards are subject to revision and parties using this standard should investigate the possibility of using the latest version of the following standards. GB/T528—1992 Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber (egvISO37:1994) GB/T1690--1992 Test method for liquid resistance of vulcanized rubber (neqISO1817:1985) GB1800.2-1998 Basis of limits and fits Part 2: Basic provisions for tolerances, deviations and fits (eqvISO286-1:1988)
GB 2941-1991
Standard temperature, humidity and time for environmental conditioning and testing of rubber specimens (eqvISO471:1983) GB/T3512-1983 (1989) Rubber hot air aging test method (neqISO188:1976) GB/T3672--1992 Dimensional tolerances for molded, extruded and calendered solid rubber products (eqvISO3302:1988) GB/T5563-1994 Hydraulic test methods for rubber and plastic hoses and hose assemblies GB/T 5564—1994
GB/T 5565—1994
GB/T 5567--1994
Bending test for rubber and plastic hoses at low temperatures (neqISO4672:1988)Bending test for rubber or plastic hoses and pure rubber hoses (neqISO1747:1973)Determination of vacuum properties of rubber, plastic hoses and hose assembliesApproved by the State Administration of Petroleum and Chemical Industry on 2000-05-23, implemented on 2000-12-01
HG/T 3666--2000
GB/T 6031-1998
Determination of hardness of vulcanized rubber or thermoplastic rubber (10~1001RHD) (idtISO48:1994)GB/T 7759--1996
Determination of compression set of vulcanized rubber and thermoplastic rubber at room temperature, high temperature and low temperature (eqvISO)815:1991)
GB/T 9573~-1988
Methods for measuring dimensions of rubber and plastic hoses and hose assemblies (idtISO4671:1984) GB/T 12833—1991
GB/T 14905—1994
HG/T 2869—1997
Analysis method of multi-peak curve of tear strength and adhesion strength of rubber and plastic (egv1S06133:1981) Determination of adhesion strength between layers of rubber and plastic hoses (eqvISO8033:1991) Evaluation of ozone resistance of rubber and plastic hoses under static conditions (idtISO7326:1991) ISO8308:1993 Determination of liquid wall permeability of rubber and plastic hoses and non-reinforced hoses 3 Types of pure hoses and hoses
Pure hoses and hoses are divided into the following three different types: Type 1: pure hose, maximum working pressure is 0.12MPa; Type 2: hose, working pressure is 0~0.12MPa; Type 3: hose, working pressure is 0~0.3MPa. In addition, the above three types of 1, 2 and 3 can be further divided into two levels: Class A: working at an ambient temperature of up to 120C; Class B: working at an ambient temperature of up to 140C. Grade B pure rubber hoses may be provided with an outer covering.
4 Inner wall of pure rubber hoses and hoses
The inner wall of all pure rubber hoses and hoses shall be clean and shall not contain any impurities during visual inspection. 5 Dimensions
5.1 Pure rubber hoses
When measured in accordance with the method specified in GB/T9573, the inner diameter and wall thickness shall comply with the provisions of Table 1. The tolerance shall be selected according to the corresponding category specified in GB/T3672: M3 for molded tubes and E2 for extruded tubes. When a lining layer is used, its thickness shall be (0.6±0.1) mm, and this thickness value shall be included in all nominal wall thicknesses shown in Table 1. Table 1 Inner diameter and wall thickness of pure rubber hose
Nominal inner diameter
5.2 Hose
Nominal wall thickness
When measured according to the method specified in GB/T9573, the size, tolerance and concentricity of the hose shall comply with the provisions of Table 2 and Table 3. When a lining layer is used, its thickness shall be (0.6±0.1) mm, and this thickness value shall be included in all nominal wall thicknesses shown in Table 2. 398
Nominal inner diameter
3.5 or less (including 3.5)
3.5 and above
HG/T 3666--2000
Hose dimensions
Hose concentricity
Maximum concentricity error
Inside diameter to outside diameter
Note; For information, the fittings that match the pure hose should have the following diameters: 4mm, 4.5mm, 6mm or 6.35mm, 8mm, 10mm, 12mm and 14 mm.
6 Physical tests and specifications
6.1 Requirements for materials
Whenever possible, the test specimens shall be cut from the product for testing. If this is not possible, the specimens shall be cut from standard test films of the same degree of vulcanization as the product. Standard specimens shall be used for the determination of compression set. 6.1.1 Hardness
When measured according to the procedure specified in GB/T6031 (micro test), the hardness shall comply with the provisions of Table 4. Table 4 Requirements for materials
Chapter number
Nominal hardness
Tensile strength, minimum
Elongation at break, minimum
Inlay
Requirements for grade A and grade B
Hose inner lining
Hose outer layer
Pure rubber hose
Chapter number
Accelerated aging
Hardness increase, maximum
Tensile strength decreases, maximum
Elongation at break decreases, maximum
Ozone resistance
Compression permanent deformation, maximum (100±1)CX(24-9)h
Hydrocarbon resistance
Hardness decreases, maximum
Tensile strength decreases, maximum
Tensile Elongation at break decreases, maximum
volume expansion, maximum
resistance to oxygenated fuels
hardness decreases, maximum
tensile strength decreases, maximum
elongation at break decreases, maximum
volume expansion, maximum
resistance to oxidized fuels
hardness decreases, maximum
tensile strength decreases, maximum
elongation at break decreases, maximum
volume expansion, maximum
resistance to No. 3 oil
tensile strength decreases, maximum
elongation at break decreases, maximum
volume change
increases, maximum
decreases, maximum
1) The maximum absolute value should not exceed 90IRHD. 6.1.2 Tensile strength and elongation at breakwww.bzxz.net
HG/T 3666--2000
Table 4 (Complete)
Lined layer
Requirements for Grade A and Grade B
Hose inner lining
Hose outer covering
Observe at 2 times magnification without cracks
Pure rubber hose
When measured using No. 2 dumbbell specimens according to the procedure specified in GB/T528, the tensile strength and elongation at break shall comply with the requirements of Table 4.
6.1.3 Changes in performance after accelerated aging
Accelerated aging tests shall be conducted in accordance with the provisions of GB/T3512 in a ventilated drying oven using the specimens specified in 6.1.1 and 6.1.2 under the following conditions:
A-grade lining, pure rubber hose, hose outer layer and hose inner layer, and B-grade lining and hose inner layer: (120±2)C×(72-2)h.
*-B-grade pure rubber hose and hose outer layer: (140±2)C×(72-2)h. Changes in hardness, tensile strength and elongation at break shall comply with the provisions of Table 4. 6.1.4 Ozone resistance
After accelerated aging according to the provisions of 6.1.3, the test shall be conducted according to the corresponding method specified in HG/T2869. When inspected with a 2x magnifying glass under the following conditions, the specimen shall not show cracking (see Table 4). Ozone partial pressure: (50±3)mPa.
Cycle: (72.2)h.
Elongation:
HG/T 3666-2000
20% for hose outer layer, inner lining layer and inlay layer; 50% for pure rubber hose (including inlay layer).
Temperature: (40±2)C.
6.1.5 Compression set
When measured under the conditions specified in Table 4 using a large specimen (Type A) as specified in GB/T7759, the compression set shall comply with the provisions of Table 4.
6.1.6 Fuel resistance
Warning: Fuel is extremely dangerous at high temperatures. The test shall be carried out in an explosion-proof cabinet under reflux conditions. 6.1.6.1 Hydrocarbon resistance (Liquid C specified in GB/T1690) This requirement is only applicable to the inner lining and lining of pure rubber hoses and hoses. After immersion in Liquid C for (72_9) hours at (60±1)°C, the hardness (6.1.1), tensile strength (6.1.2), elongation at break (6.1.2) and any change in volume shall comply with the provisions of Table 4. 6.1.6.2 Oxygenated fuel resistance
This requirement is only applicable to the lining and lining of pure rubber hoses and hoses. After immersion in a mixture of 85% Liquid C and 15% methanol by volume at (60±1)°C for (722) hours, the hardness (6.1.1), tensile strength (6.1.2), elongation at break (6.1.2) and any change in volume shall comply with the provisions of Table 4.
6.1.6.3 Resistance to oxidation fuel
This requirement applies only to the lining and inner lining of pure rubber hoses and soft tubes. After being immersed in the test liquid specified in Appendix A for (140±2)h at (60±1)C, the hardness (6.1.1), tensile strength (6.1.2), elongation at break (6.1.2) and any change in volume shall comply with the provisions of Table 4. 6.1.7 Resistance to No. 3 oil
This requirement applies only to the outer covering of pure rubber hoses and soft tubes. After the A-grade product samples are immersed in No. 3 oil at (120±2°C) and the B-grade product samples are immersed in No. 3 oil at (140±2°C) for (72.2) hours, the test is carried out according to the procedure specified in GB/T1690. The tensile strength (6.1.2), elongation at break (6.1.2) and any change in volume shall comply with the provisions of Table 4.
6.2 Requirements for finished products
6.2.1 Leakage test
This requirement is only applicable to pure rubber hoses.
Put the pure rubber hose on the polished end of a metal pipe. The mechanical tolerance of the metal pipe is defined as H14 according to GB1800.2, and its diameter should be equal to the corresponding value given in the note of 5.2. The pure rubber hose is placed along the metal The distance the tube is pushed inward should be 3 times the nominal inner diameter of the pure rubber hose. The other end of the metal tube should be closed, and the other end of the pure rubber hose should be connected to the air pressure source. Then, the assembly is subjected to an internal pressure of 0.12MPa and maintained for 2 minutes. The medium is liquid C. No leakage should occur during the test (see Table 5).
Table 5 Requirements for finished products
Chapter number
Leakage test
Tensile test
Minimum burst pressure
Pure rubber hose
No leakage
No breakage or slippage
Chapter number
6.2.12 and
Adhesion strength
Minimum separation force
HG/T 3666—2000
Table 5 (end)
Cover and lining to reinforcement
Liner to lining
Flexibility at low temperature
Cleanliness
Insoluble impurities, maximum
Solids soluble in fuel, maximum
Extractable wax products, maximum
Permeability of liquid C, maximum
Tear resistance, minimum
Suction resistance
Bending resistance
Deformation coefficient D'/D
Long term Resistance to oxygenated fuels and oxidation
Fuel performance
Suck-flattening resistance
Bending resistance
Deformation coefficient D'/D), minimum
Ozone resistance
Minimum bursting pressure
Adhesion strength
Minimum separation force
-Outer layer and inner lining layer to reinforcement layer
Inlay layer to inner lining layer
Low temperature flexibility
Accelerated aging
6.2.2 Tensile test
This requirement applies only to pure rubber hoses.
cm2/m2
Pure rubber hose
2 times magnification, no signs of cracks
The ball should be able to pass through the entire hose
The ball should be able to pass through the entire hose
2 times magnification, no signs of cracks
2 times magnification, no signs of cracks
2 times magnification, no cracks or erosion inside or outside
According to 6.2.1 The method described above is to put a section of pure rubber hose on one end of the metal pipe, and then hang the assembly vertically along the metal pipe, and make the pure rubber hose bear a 10N load applied to the other end plugged with a plug. The pure rubber hose should not break or slip off (see Table 5). 6.2.3 Minimum bursting pressure
The minimum bursting pressure measured according to the procedure specified in GB/T5563 shall comply with the provisions of Table 5. 6.2.4 Adhesion strength
This requirement is only applicable to hoses and pure rubber hoses with inner lining. The adhesion strength between each layer measured according to the corresponding method specified in GB/T14905 shall comply with the provisions of Table 5. 6.2.5 Low temperature flexural properties
This test should be carried out according to method B specified in GB/T5564 under the following conditions. Empty pure rubber hose or hose: (25±2)C (24--2)h. Pure rubber hose filled with liquid C: (-40±2)C (72_2)h. 402
HG/T 3666-2000
The time interval between filling the pure rubber hose or soft tube with liquid and the start of freezing should not be more than 30 minutes. The bending radius of the soft tube should be 12 times its nominal inner diameter, and the bending radius of the pure rubber hose should be 25 times its nominal inner diameter. After bending, check with a 2x magnifying glass, and the pure rubber hose or soft tube should not show signs of cracking (see Table 5). Note: The "empty test" widely used in industry is only used for arbitration tests. 6.2.6 Cleanliness
The impurity content measured according to Appendix B shall comply with the provisions of Table 5. 6.2.7 Determination of wax products extracted with liquid C The content of extractable wax products measured according to Appendix B shall comply with the provisions of Table 5. 6.2.8 Liquid C penetration
According to method A specified in ISO8308 (see Appendix E), the liquid C penetration value measured at (40±1)°C for (100±2)h shall comply with the provisions of Table 5.
6.2.9 Tear resistance
This requirement is only applicable to pure rubber hoses.
The tear resistance measured according to Appendix C shall comply with the provisions of Table 5. 6.2.10 Suction resistance
This test shall be carried out under the following conditions Under the following conditions, the test is carried out only on straight hoses according to method A specified in GB/T5567: vacuum degree: 80kPa;
cycle: 15~60s;
ball diameter: nominal inner diameter X0.8.
The ball should be able to pass through the entire hose (see Table 5). 6.2.11 Bending resistance
This requirement is only applicable to straight pure rubber hoses and hoses with an inner diameter not exceeding 16mm. The test should be carried out in accordance with GB/T5565, and the reel diameter used is as follows: 140mm for pure rubber hoses and hoses with a diameter of 7~~11mm (including 11mm). 220mm for pure rubber hoses and hoses with a diameter of 12~16mm (including 16mm). The deformation coefficient D'/D should conform to the value specified in Table 5. 6.2. 12 Long-term resistance to oxygenated fuel
Pure rubber hose or hose specimens shall be subjected to a long-term cycle test with oxygenated fuel for 1000 hours at (60±1)°C in accordance with the provisions of Appendix D. The first specimen shall then be subjected to the tests specified in 6.2.12.1 to 6.2.12.4. The second specimen shall be subjected to the test specified in 6.2.12.5. The third specimen shall be subjected to the test specified in 6.2.12.6. 6.2.12.1 Resistance to flattening: When tested in accordance with the method specified in 6.2.10, the ball shall pass through the entire hose (see Table 5). 6.2.12.2 Bending resistance: The deformation coefficient D'/D measured in accordance with 6.2.11 shall comply with the values specified in Table 5. 6.2.12.3 Ozone resistance: Test in accordance with the method specified in HG/T2869 under the following conditions. 1 Carry out the test. Check with a 2x magnifying glass. The sample should not show any signs of cracking (see Table 5).
Ozone partial pressure: (50 ± 3) mPa.
Cycle: (72_2) h.
Elongation:
20% for hose outer layer, inner lining and lining; 50% for pure rubber hose (including lining).
Temperature: (40 ± 2) C.
6.2.12.4 Minimum burst pressure: The minimum burst pressure measured in accordance with 6.2.3 shall comply with the provisions of Table 5. 6.2.12.5 Adhesion strength: The adhesion strength between the outer layer and the inner lining and the reinforcement layer 403
measured in accordance with 6.2.4 using the second sample specified in 6.2.12 shall comply with the provisions of Table 5. HG/T3666--2000
6.2.12.6 Low temperature flexural properties: According to the provisions of 6.2.5, the third sample in 6.2.12 shall be tested. When inspected under a 2x magnifying glass, no cracking shall occur (see Table 5). 6.2.13 Long-term resistance to oxidized fuel
Pure rubber or hose samples shall be subjected to a long-term cycle test for 1000 hours at (60±1)C using the oxidized fuel prepared as described in Appendix A and in accordance with the provisions of Appendix D. Then, one sample shall be used to conduct the tests specified in 6.2.12.1 to 6.2.12.4. Two more samples shall be taken for the tests specified in 6.2.12.5 and 6.2.12.6 respectively. The test results shall meet the requirements specified in 6.2.12.1 to 6.2.12.6 respectively (see Table 5). 6.2.14 Changes in properties after accelerated aging
Bend a pure rubber hose or soft hose sample of appropriate length into a ring with two ends connected and a diameter of approximately 250 mm, and place it in a ventilated oven at (150 ± 3)°C for aging for (72.9) hours. At the end of the aging cycle, straighten the sample for 4 to 8 seconds. After straightening, check with a 2x magnifying glass. There should be no signs of cracking or corrosion inside or outside the sample (see Table 5). 7 Marking
Unless the components are too small to be marked, pure rubber hoses and soft hoses should be printed with a mark containing the following information: a) fuel;
b) manufacturer's name or trademark:
c) number of this standard;
d) type and grade;
e) year and month of manufacture;
f) inside diameter.
A1 Range
HG/T 3666--2000
Appendix A
(Standard Appendix)
Preparation of Oxidized Fuel Test Fluids
This appendix specifies methods for preparing oxidized ("acidic") gasoline test solutions used to determine their effects on elastomeric, plastic, and metallic materials and components. This appendix applies to peroxide number solutions of PN 90 prepared using tert-butyl hydroperoxide (70% aqueous solution), soluble copper ions (0.01 mg/dm) and a base fuel containing 80% by volume of Liquid C, 15% methanol and 5% 2-methylpropan-2-ol (tert-butyl alcohol). When required by engineering drawings or specifications, other Other base fuels and peroxide numbers, but it should be noted that some base fuels may produce aqueous phase separation of the peroxide solution. This appendix also describes the determination of the fuel peroxide number. A2 Reagents
Unless otherwise specified, only analytical grade reagents and distilled water or water of equal purity are used in the analysis. A2.1 Tert-butyl hydroperoxide: 70% aqueous solution, p0.935g/cm2. A2.2 Copper ion concentrate: A solution of copper cyclohexane containing 6% to 12% copper by mass in a suitable hydrocarbon as solvent. A2.3 2, 4-trimethylpentane (isooctane). Warning: low flash point.
A2.4 Toluene.
Warning: low flash point.
A2.5 Methanol.
Warning: Low flash point.
A2.6 2-Methylpropan-2-ol (tert-butyl alcohol). Warning: Low flash point.
A3 Apparatus
A3.1 Polyethylene bottle: 1000 mL, wide mouth with screw cap. A3.2 Glass volumetric flask: 1000 cm2. A3.3 Graduated pipette: 10 cm2. A3.4 Graduated glass cylinder: 100 cm2 and 1000 cm2. A4 Preparation steps
Warning: The preparation steps must be carried out in a fume hood, and protective glasses and disposable plastic gloves must be worn. A4.1 Preparation of test liquid||tt| |A4.1.1 Base fuel mixture
Mix equal volumes of 2,2,4-trimethylpentane and toluene to prepare GB/T1690 liquid C and store in a dark glass bottle. Mix liquid C, methanol and 2-methylpropan-2-ol specified in GB/T1690 in a volume ratio of 80:15:5 to prepare base fuel and store in a dark glass bottle.
A4.1.2 Copper ion stock solution (1 mg/dm2) Add an appropriate volume of copper ion concentrate to the base fuel to prepare a 1000cm copper ion solution (Cu-1) with a concentration of 1.140 mg/dm2. Store in a dark glass bottle. 405
HG/T 3666--2000
Add 100cm of Cu-1 to 1040cm2 of base fuel to prepare 0.1 mg/cm2 copper ion solution (Cu-2). Store in a dark glass bottle.
Add 100 cm2 of Cu-2 to 990 cm2 of base fuel to make a 1.0 mg/cm2 copper ion stock solution (CSS). Store in a dark glass bottle.
A4.1.3 Preparation of Oxidized Fuel Test Liquid Use the mixture specified in Table A1 to make an oxidized gasoline test liquid of the required working strength. Store in a polyethylene bottle in the dark for no more than four weeks. Immediately after mixing and before subsequent use, check the peroxide index by the titration test method described in A5. Use a 1000 cm2 volumetric flask to hold 500 cm2 of base fuel and add the tert-butyl hydroperoxide solution and the copper ion stock solution (CSS). Then fill to 1000 cm2 with base fuel and shake thoroughly to dissolve the water in the hydrogen peroxide solution in the ethanol phase of the base fuel. Table A1 Preparation of Oxidized Fuel Test Fluids
Expected Peroxide Number
70% tert-butyl hydroperoxide solution
Note: 1 Peroxide Number (PN) - 1 mmol/dm copper ion stock solution (CSS)
Base fuel
To 1000 cm3
Recheck the PN of the test fluid after every 70 h of use. If it drops below 80 PN, replace the old test fluid with a new test fluid.
A5 Titration of the Peroxide Number of Oxidized Fuel Test Fluids A5.1 Scope
This section specifies the titration method for determining the peroxide number of oxidized ("acidified") gasoline test fluids prepared by the procedure specified in A4.
This method can be used to determine the peroxide number of oxidized gasoline test fluids during immersion tests. The following observations should then be made: a) Most immersion tests involving elastomers will result in yellowing of the test fluid due to the extraction of compounding ingredients from the rubber. →This should be taken into account when determining the endpoint of the titration.
b) The complexing agent extracted from the material during the test has the ability to release free iodine from the iodide solution. Therefore, a blank test should be carried out in the repeated immersion tests using a base fuel that does not contain hydrogen peroxide. This method can also be used (with certain measures) to determine the loss of peroxide number of the test liquid used during the immersion test in order to determine the amount of test liquid that needs to be replenished.
A5.2 Reagents
Unless otherwise specified, only analytical reagents and distilled water or water of equal purity should be used in the analysis. A5.2.1 Potassium iodide: 100g/dm solution, stored in a dark reagent bottle. If the solution gives a peroxide number of 2 during the blank titration, it should be discarded.
A5.2.2 Sodium thiosulfate standard titration solution: c (Na2S, O.) = 0.1 mol/dm. A5.2.3 Acetic acid/propan-2-ol mixture: Mix 100 mL of glacial acetic acid and 1150 mL of propan-2-ol and store in a glass bottle. A5.3 Apparatus
A5.3.1 Erlenmeyer flask: ground-mouth, 250 cm2 capacity. A5.3.2 Condenser: Allihn or Liebig water-cooled, with ground-mouth connector for connection to the Erlenmeyer flask (A5.3.1). A5.3.3 Glass measuring cylinder: 100 cm2 capacity. A5.3.4 Hot plate or other heating tool: should be suitable for heating the Erlenmeyer flask equipped with a condenser to reflux the reagents. A5.3.5 Glass pipette: 10 cm2 capacity. A5.4 Procedure
A5.4.1 Add 25 mL of the acetic acid/propan-2-ol mixture to a 250 cm2 Erlenmeyer flask. A5.4.2 Add 10 cm potassium iodide solution to the conical flask.
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