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GB/T 7304-2014: Standard test method for acid number of petroleum products by potentiometric titration
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Standard test method for acid number of petroleum products by potentiometric titration
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GB/T 7304-2014
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| GB/T 7304-2000 | English | 399 |
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Petroleum products and lubricants. Determination of acid number. Potentiometric titration method
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Petroleum products and lubricants--Determination of neutralization number--Potentiometric titration method
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Basic data | Standard ID | GB/T 7304-2014 (GB/T7304-2014) | | Description (Translated English) | Standard test method for acid number of petroleum products by potentiometric titration | | Sector / Industry | National Standard (Recommended) | | Classification of Chinese Standard | E30 | | Classification of International Standard | 75.080 | | Word Count Estimation | 19,176 | | Date of Issue | 2/19/2014 | | Date of Implementation | 6/1/2014 | | Older Standard (superseded by this standard) | GB/T 7304-2000 | | Quoted Standard | GB/T 4756; GB/T 4945; GB/T 6682-2008; SH/T 0079; SH/T 0163; SY/T 5317 | | Adopted Standard | ASTM D664-2011a, MOD | | Regulation (derived from) | 2014 National Standards Bulletin No. 2 | | Issuing agency(ies) | General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China, Standardization Administration of the People's Republic of China | | Summary | This Standard specifies two methods of petroleum products, lubricants, bio-diesel and bio-diesel fuel blending acid value determined by potentiometric titration. A method for the determination of the basic can be dissolved and dissolved in toluene and anh | GB/T 7304-2014: Standard test method for acid number of petroleum products by potentiometric titration
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Standard test method for acid number of petroleum products by potentiometric titration
ICS 75.080
E30
National Standards of People's Republic of China
Replacing GB/T 7304-2000
Petroleum products - Determination of acid number potentiometric titration
Issued on. 2014-02-19
2014-06-01 implementation
Administration of Quality Supervision, Inspection and Quarantine of People's Republic of China
Standardization Administration of China released
Foreword
This standard was drafted in accordance with GB/T 1.1-2009 given rules.
This standard replaces GB/T 7304-2000 "Petroleum products and lubricants - Determination of acid method (potentiometric titration)." This standard
GB/T 7304-2000 compared to the main technical changes are as follows.
--- Name to "acid number of petroleum products by potentiometric titration";
--- To increase the scope of biodiesel and biodiesel blended fuel was measured in acid number;
--- The standards are divided into A, B two methods, Method B content is newly added;
--- Reference electrode in electrolytic solution filled modify 1mol/L ~ 3mol/L ethanol electrolyte lithium chloride;
--- Deletion of pyridine and 2,4,6-trimethyl-nitro-m-cresol requirements;
--- Remove the preparation method of the non-aqueous buffer solution of relevant content;
--- Detecting electrode system requirements for pH values between 4 and 7 aqueous buffer solution of the difference between the potential value of greater than 162mV
Can;
--- Original standard 8.3 as a separate chapter, namely Chapter 9;
--- In aqueous buffer solution of the potential value of the titration end point as a non-significant turning point in time;
--- Increased quality control checks of the contents;
--- Modified precision;
--- Added Appendix A (informative), the original Appendix A (informative appendix) to Annex B (informative).
This standard uses redrafted law revision adopted ASTMD664-11a "Petroleum products - Determination of acid number (potentiometric titration)."
Technical differences between this standard and ASTMD664-11a and the reasons are as follows.
--- Terms and definitions are added to the definition of a strong acid value;
--- References of standards adopted corresponding national standards and industry standards;
--- Increased ordinary reference electrode, because of domestic casing reference electrode so few in this standard reference electrode and the casing
Domestic universal reference electrode can be used;
--- Increasing the preparation of an aqueous buffer solution;
--- Added Appendix B (informative) "synthetic acid value measurement requirements."
This standard by the National Standardization Technical Committee on products and lubricant oil (SAC/TC280) proposed.
This standard by the National Petroleum Products and Lubricants Standardization Technical Committee of petroleum fuels and lubricants Technical Committee
(SAC/TC280/SC1) centralized.
This standard was drafted. China PetroChina Lanzhou lubricant research and development centers.
The main drafters. Zhang Dahua, Zhouya Bin, Wei Xiaonuo, Jing Shi.
This standard replaces the standards previously issued as follows.
--- GB/T 7304-1987, GB/T 7304-2000.
Petroleum products - Determination of acid number potentiometric titration
Warning. This standard relates to certain hazardous materials, operations and equipment, but has no intention of all safety issues are related to this proposed construction
Meeting. Therefore, users in the use of this standard to establish appropriate safety and protective measures, and determine the applicability of regulatory limitations related.
1 Scope
This standard specifies the analyzes of the two measuring petroleum products, lubricants, biodiesel and biodiesel blended fuel acid number potentiometric titration
Setting Method.
A suitable method can be dissolved and substantially dissolved in toluene and anhydrous isopropanol mixed solvent of petroleum products and lubricants acid value
Determination. Method A sample can be determined as those in the water dissociation constant greater than 1 × 10-9 acidic component, the dissociation constant of less than 1 × 10-9
Extremely weak acids do not interfere, but hydrolysis constant is greater than 1 × 10-9 salts will participate in the reaction, the precision of Method A is the acid value (in
KOH basis) of 0.1mg/g ~ 150mg/g in the range established.
Method B has a low acidity and is suitable for measuring large differences in solubility of biodiesel and biodiesel blended fuel acid number.
Note. The new oil or used oil is acidic components include organic acids, inorganic acids, esters, phenolic compounds, lactones, resins, and heavy metal salts, ammonium salts and other weak base
Salts, polycarboxylic acids and acid salts of certain antioxidants and detergent additive.
This standard reflects the relative displacement of oil during use under oxidizing conditions occur without regard to color and other performance changes premise
Of. Although the titration is carried out under certain conditions, but this standard can not be used to determine the absolute acidity of oil to predict its use state
Performance, did not find a causal link between the acid value and bearing corrosion.
Note 1. The acid value of the results by this standard and measured by GB/T 4945 and SH/T 0163 measured results may be the same or may be different. This standard does not
Try the measurement result of the measurement results and other ways to get non-titration was associated.
Note 2. There are observed when using an aqueous or non-aqueous buffer solution in this standard, there are some differences between the results obtained are few laboratories.
2 Normative references
The following documents for the application of this document is essential. For dated references, only the dated version suitable for use herein
Member. For undated references, the latest edition (including any amendments) applies to this document.
GB/T 4756 petroleum liquids hand sampling method (GB/T 4756-1998, eqvISO 3170. 1988)
GB/T 4945 Petroleum products and lubricants - Determination of acid and base number (Color Indicator Method)
GB/T 6682-2008 analytical laboratory use specifications and test methods (ISO 3696. 1987, MOD)
SH/T 0079 Petroleum products testing reagent solution preparation method
SH/T 0163 Petroleum products - Determination of total acid (Semi - Micro Color Indicator Method)
SY/T 5317 petroleum liquids pipeline automatic sampling (SY/T 5317-2006, ISO 3171. 1988, IDT)
3 Terms and Definitions
The following terms and definitions apply to this document.
3.1
Acid value acidnumber
The specimen in the specified solvent base titration end point is specified to be used in an amount in dollars KOH, in units of mg/g.
Note. The use of this standard in the base is dissolved in a mixed solvent containing toluene, anhydrous isopropanol and a small amount of water per gram of sample from the initial potentiometric titration
A new quality to the appropriate aqueous alkaline buffer solution with a potential value or titration to this standard when the inflection point using potassium hydroxide (in milli
Grams) represented.
3.2
Acid value strongacidnumber
Amount and 1g sample strongly acidic components required for a base to KOH counted in units of mg/g.
Note 1. This standard will be dissolved in a mixed solvent per gram of sample from the initial to the corresponding new potentiometric titration with an acidic aqueous buffer solution potential value or standard
When the inflection point in a predetermined KOH used to count (in units of mg/g) The amount of the base value is reported as a strong acid.
Note 2. Due to production and to acid components and other acidic components are different, so when the user of this standard after the discovery of these two components, respectively, should be
To report.
4. Summary
The sample is dissolved in a solvent in the titration, potassium hydroxide standard solution as titrant isopropanol potentiometric titration, electrodes used for glassy
Electrode and a reference electrode or composite electrode glass indication. Manual or automatic drawing draw potential mV value corresponding to the volume of the titration potentiometric titration song
Line, and the apparent jump point as the end point, if there is no obvious jump points are measured potential values for the corresponding new feature aqueous buffer solution of acid and base
The endpoint of the titration.
5 Methods
5.1 with new or petroleum products, biodiesel and biodiesel blended fuel additives, there may be some in the form of oil or in making
During use of the degradation products (e.g., oxidation products) in the form of an acidic component. It can be determined by titration with an alkaline solution containing these substances relative
The amount of acid value is measured under specified conditions have these substances in the amount of oil in the acid value can be used to control the quality of lubricating oil in the formulation studies,
Sometimes it can also be used to determine the lubricating oil in the course of the degradation, but the acid value as a lubricant scrapped indicators should be determined by experience.
5.2 Due to the various oxidation products contribution acid number is different, and corrosion properties of different organic acids are also different, so the standard
It can not be used to predict oil, biodiesel and biodiesel blended fuel in the course of corrosion. Biodiesel is not found and Health
There was the inevitable link between diesel fuel and lubricating oil blending an acid value of its corrosion of the metal trend.
6 Instruments
6.1 manual titration device
6.1.1 potentiometer or voltmeter. When the electrode is in line with the provisions of 6.1.2 and 6.1.3, and the resistance between the two electrodes between 0.2MΩ ~
When 20MΩ, potentiometer or voltmeter accuracy of ± 0.005V, sensitivity of ± 0.002V, the range of at least ± 0.5V. Potentiometer should be connected
In order to prevent the entire operation due to the exposure that touching ground, the glass electrode surface portion, the glass electrode wire, such as Taiwan and production titration
Students have an impact on potential electrostatic field meter readings.
Note. The instrument may also be a design input is less than 5 × 10-12A continuous readings of resistance voltmeter input terminal electron volt meter and more than one access
1000MΩ and through the metal shield grounding electrode system components, while the shield wire voltmeter and a glass electrode is connected to the outside to prevent static electricity
interference.
6.1.2 Detection electrode. suitable for non-aqueous titration of standard pH electrodes.
6.1.3 reference electrode. calomel electrode or silver/silver chloride reference electrode, filled with 1mol/L ~ 3mol/L ethanol solution of lithium chloride.
6.1.4 composite electrode. Built in the detection electrode and a silver/silver chloride reference electrode, such as the use and maintenance of the electrode structure to provide a party
Then, the composite electrode in the reference section has a sleeve diaphragm, ethanol and inert electrolyte, such as a concentration of 1mol/L ~
3mol/L ethanol solution of lithium chloride, a composite electrode which has the same or better response of the two-electrode system. It has a removable
Removable sleeve diaphragm to facilitate cleaning and added electrolyte.
NOTE. The third electrodes such as platinum electrode, the electrode can be increased stability in some systems.
6.1.5 variable speed mechanical stirrer. any form can be, but it should be equipped with a spiral stirrer. Stirring speed should not spill
Liquid into the bubble solution and not the premise, to provide as severe agitation. 6mm and radius of the blade inclination is 30 ° ~
Impeller 45 ° should be to meet the requirements. Magnetic stirring while also meet the requirements.
NOTE. If you use electronic mixing equipment, mixing equipment with the correct power mode and grounded to prevent the titration process due to open or close stirred
Motor power and impact on the potentiometer readings.
6.1.6 Buret. capacity of 10mL or other specifications, the smallest scale 0.05mL or less, with an accuracy of ± 0.02mL. Burette
Tip should grow Hancock 100mm ~ 130mm, so before entering the titration titrant bottle does not come into contact with the surrounding air and other vapors.
Potassium hydroxide burette should be fitted with protective tube material adsorbed built a base of lime or other carbon dioxide.
6.1.7 beaker. a capacity of 250mL, made of borosilicate glass or other suitable material.
6.1.8 Titration stand. the ability to place the electrode, stirrer and burette like table.
NOTE. reasonable arrangement in order to move the cup does not interfere with the electrode and stir.
6.2 automatic titration equipment
6.2.1 automatic titration system should ensure that the analysis process can be specified in the standard. The bottom line is. automatic potentiometric titrator should be guaranteed to meet
6.1 Performance and requirements.
6.2.2 titrant added dynamic mode. During the titration, the addition rate and the amount of titrant depends on changes in the system
rate. The recommended maximum increment is 0.5mL, minimum increment 0.05mL.
6.2.3 cylinder. 50mL, or other measure (50 ± 0.5) mL liquid measuring instruments.
6.2.4 pipette. 2mL, A grade.
6.2.5 beaker. a capacity of 125mL, 250mL or other appropriate size beaker, borosilicate glass or other suitable material
production.
7 Reagents
7.1 purity reagents. chemical reagents used in this standard were of analytical grade. In determining the level of the other agents do not have sufficient purity
The case will affect the accuracy of the measurement results, the other grade reagents may also be used.
7.1.1 The solution may be used instead of commercially available laboratory prepared their own solution, has proved to be feasible.
Volume of the solution prepared in 7.1.2 with this standard is different, but the final concentration should be consistent.
7.2 Water. Unless otherwise specified, the water used in this standard shall comply with GB/T 6682-2008 specified in Ⅲ grade water.
7.3 reference material. a solution of commercially available reference material or reference material for calibration titrant.
7.4 ethanol.
Warning. flammable, toxic denatured enable people were poisoned.
7.5 lithium chloride, LiCl.
Electrolyte lithium chloride 7.6. 1mol/L ~ 3mol/L ethanol solution of lithium chloride.
7.7 potassium hydroxide.
Warning. Can cause severe corrosion.
7.8 Anhydrous isopropanol. water content is less than 0.1%. If you can not obtain a sufficient drying agent, by having a multilayer tray distillation column to
Purifying reagent dried Discard the first 5% of distillate, using the remaining 95%. Dried zeolite can also be used to achieve the purpose, e.g., can
With Linde type 4A molecular sieves, the solvent can downwardly through the molecular sieve column, molecular sieve and solvent ratio of 1.10.
WARNING. Flammable.
NOTE. It is reported that if the added restriction does not prohibit, isopropanol may contain peroxide. If so, when a container containing isopropanol or agent
Empty bottles close when dry or explosion may occur.
7.9 pH were commercially available aqueous buffer solution of 4, 7 and 11. Above buffer solution should be based on a more regular basis their stability
Change, or that should be replaced has been contaminated. About the stability of these substances can get the information needed from the manufacturer.
Above aqueous buffer solution may also be allowed to prepare in the laboratory.
7.9.1 pH value of buffer solution 4. Weigh in (115.0 ± 5.0) ℃ sulfate, potassium hydrogen phthalate reference reagent of 2h ~ 3h
10.12g, dissolved carbon dioxide-free distilled water, diluted to 1000mL in at 25 ℃.
7.9.2 pH value of buffer solution 7. Weigh in (115.0 ± 5.0) ℃ dried potassium dihydrogen phosphate reference reagent 6.81g 2h ~ 3h, add
0.1mol/L sodium hydroxide solution 291mL, diluted with carbon dioxide-free distilled water at 25 deg.] C to to 1000mL.
7.9.3 pH value of buffer solution 11. Weigh sodium bicarbonate reference reagent 2.10g, add 0.1mol/L sodium hydroxide solution 227mL, with
Carbon dioxide-free distilled water to dilute to 1000mL at 25 ℃.
8 electrode system
8.1 Electrode preparation
Silver/silver chloride reference electrode prior to use, if not contained therein electrolyte 1mol/L ~ 3mol/L ethanol solution of lithium chloride
Fluid should be replaced. Discharge of electrolyte from the electrode, first with distilled water and wash all the salt which was then washed with ethanol. Then lithium chloride
Ethanol electrolyte rinse several times. Finally, the sleeve diaphragm electrode on the back in place and by adding holes to the inner electrode of lithium chloride was added
Ethanol electrolyte diaphragm when the casing or removing the electrolyte within the electrode should ensure free access to the titration system. Composite electrode
The same manner. Electrolyte composite electrodes can be removed by vacuum suction.
8.2 detection electrode
When the electrode for the first time or add a new electrolyte and set aside in a long time after all to deal with potentiometer - combination electrode into
Line testing. Rinse the electrode first with solvent and then rinse with water. The electrode is then immersed in an aqueous buffer solution of pH 4. Stir
Read potentiometer mV value after 1min. Rinse out electrode. The electrode immersed in an aqueous buffer solution pH value of 7. stir
Read potentiometer mV value mix after 1min. Potentiometer mV difference between the two measured value calculation, a good electrode system should have at least
162mV (20 ℃ ~ 25 ℃) potential difference. If the potential difference is less than 162mV, gently lift the electrode sleeve diaphragm, so that a small amount charge
Electrolyte overflow, then reset the diaphragm casing, re-test. If the potential difference is still less than 162mV, clean or replace the electrode. If you check in
Measuring electrode and the reference electrode are independent of a pair of electrodes can be regarded as a unit. If one is replaced, it may be considered to form a
A different pair of electrodes should be re-tested.
Maintenance and preservation of the electrodes 8.3
Thoroughly cleaned electrode surface ground glass joints to ensure no foreign objects regularly electrode potential for a stable potential test
is very important. Electrode contamination may cause instability, erratic and difficult to observe liquid contact potential. This is for the titration
Select the inflection point on the curve as the titration end point titration is probably not very important, but the choice of a fixed potential as the end point of titration
The titration process is very important.
Note. Appendix A shows the performance of the electrode inspection program.
8.3.1 glass electrode according to the type of usage and analysis of samples require periodic (weekly continuous use at least once) is not immersed
Strong oxidizing chromium-containing cleaning solution for cleaning. It should be cleaned regularly when the reference electrode during use or install new electrodes.
It should be changed once a week filling the reference electrode electrolyte, charged the new ethanol electrolyte lithium chloride, in each case plus charge to the entrance. To ensure that the electrodes
No liquid bubbles. If you look at the bubbles, the electrode vertically and flick the bubbles out of the electrode. During the titration
It should remain the reference electrode in an electrolyte level higher than the level of the liquid titration cell.
8.3.2 Before each titration should be well prepared electrode in distilled water (pH value of 4.5 to 5.5) are soaked for at least 5min, prior to use
Washed with anhydrous isopropanol and titration solvent.
8.3.3 When not in use, the lower half of the reference electrode was immersed in ethanol lithium chloride electrolyte. When using a glass electrode, with storage
HCl acidified pH of 4.5 to 5.5 in water. In between the two titrations apart a long time, never allow the two electrodes inserted
Titration solvent. Although the electrodes are not very fragile, but in the course should be very careful.
8.3.4 electrode life. In general, according to usage, life of the electrode in the three months to six months. If you use electrodes beyond Week
Period, should be tested before use (see 8.2).
9 Instrument Calibration
9.1 Determination of an aqueous buffer solution voltmeter readings. When the titration curve can not get the exact inflection point, in order to ensure the end of the selected comparable
Sex should be using an aqueous buffer solution of acid or base per day for each electrode to obtain a voltmeter readings.
NOTE. hydrogen ion activity different glass electrode is different. Thus, for each electrode measurement system should be regularly selected as the end point of titration of acid or base buffer
Chong potential of the solution.
9.2 The electrodes are immersed in a pH 4 buffer solution and a pH of 11, stirred for about 5min, to maintain the temperature in the buffer solution
Titration within ± 2 ℃ temperature range. Read potential values, respectively. When no titration curve inflection can use this as a potential endpoint of the titration.
10 used to prepare Oil Samples
10.1 Due to the used oil sample sediments exhibit acidic or alkaline, or adsorption of the oil sample in acidic or alkaline substances, therefore, sampling
Sampling procedures should be strictly observed. Otherwise samples collected unrepresentative, causing a large measurement error.
10.1.1 sampling in accordance with the provisions of GB/T 4756 or SY/T 5317's.
10.1.2 When the sample when the used lubricant products, the sampling process the sample should be representative. And it can not be contaminated from outside.
Note. Due to the used lubricant sample significant changes may occur during storage, sampling from the lubrication system, should be measured immediately, and indicate the sampling and
Determination Date.
10.2 In order to sample sediment evenly spread out, heated and stirred in the original containers in the sample at at 60 ℃ ± 5 ℃. Such as
If the amount of the sample container vessel volume exceeds three-quarters of the sample should be transferred to clean glass bottles, the bottle should be higher than the volume of the sample
Volume of at least one-third larger. When the transfer of the specimen, so that the container should be shaken vigorously in sediment transfer all out.
Note. When the sample without significantly sediments, the above heating step can be omitted.
10.3 When sediment samples evenly spread out in the future, some or all of the samples through a pore size of about 150μm sieve conducted
The sample was filtered to large particulate matter.
Note. When the sample without significantly sediments, the above filtration step can be omitted.
11 Method A
11.1 Reagents
11.1.1 see Chapter 7.
11.1.2 hydrochloric acid (HCl). the relative density of 1.19.
Warning. corrosive and can cause burns.
11.1.3 toluene.
WARNING. Flammable.
11.1.4 hydrochloric acid isopropyl alcohol standard solution (0.1mol/L). Take 9mL hydrochloric acid and 1L of anhydrous isopropyl alcohol, the calibration is not with 125mL
Dilution water containing carbon dioxide about 8mL (accurately weighed) 0.1mol/L potassium hydroxide standard solution of isopropanol, and this solution was diluted to titrate
Agents, potentiometric titration of hydrochloric acid solution in isopropanol above calibration, calibration frequency to the calibration error is less than 0.0005mol/L is appropriate.
11.1.5 isopropanol standard solution of potassium hydroxide (0.1mol/L). Weigh 6g of potassium hydroxide was added to 1L of anhydrous isopropanol, micro-boiling
10min, the solution was allowed to stand 2d, then the supernatant was filtered with sand core funnel, and the filtered solution was stored in chemical-resistant reagent bottle,
In order to avoid interference of carbon dioxide in the air, the installation of asbestos-filled base or soda lime desiccant drying tube to the reagent bottle, this can be avoided
Solution with a cork, and a saponification contact with rubber piston grease. When the calibration of potassium hydrogen phthalate dissolved carbon dioxide-free water to
This is the titrant, potentiometric titration calibration, calibration frequency to the calibration error is less than 0.0005mol/L is appropriate.
11.1.6 titration solvent. A (5 ± 0.2) mL water was added to (495 ± 5) mL of anhydrous isopropanol and mix well, ...
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