GOST 5985-79

INTERSTATE NY STANDARD

PETROLEUM PRODUCTS

ACIDITY METHOD
AND ACID NUMBER

IPC PUBLISHING STANDARDS
Moscow

INTERSTATE STANDARD

Introduction date 01. 01. 80

This standard applies to light petroleum products (leaded and unleaded gasolines, naphthas,kerosene, diesel fuel, jet fuel), unalloyed e oils, special oils and hydrocarbon greases and establishes methods for the determination of acidity and acid number.

The essence of the method lies in the titration of acidic compounds of the test product with an alcoholic solution of potassium hydroxide in the presence of a color indicator and the determination of acidity for light oil products, expressed in mg KOH / 100cm 3, for oils and lubricants - acid number, expressed in mg KOH / g.

1. EQUIPMENT, REAGENTS AND MATERIALS

FlaskKn -1 - 100- 29/ 32 TC, Kn -2-100- 34 THS, Kn- 2-100-22 THS, Kn -1- 250- 29/ 32 TS, Kn- 2- 250- 34, K GU- 2- 1-1000-29/32 TS, KGU-2-2-1000-34 THS according to GOST25336.

Dephlegmator with a length of at least 400mm.

RefrigeratorsHT P - 1- 400- 14/ 23, ХШ -1- 400- 29/ 32 ХС, ХШ- 3- 400 THS according to GOST25336 or air cooler, or glass tubes, length 700 -750mm with inner diameter 10 - 12 mm.

Cylinders according to GOST1770 types 1- 50; 1- 100; 3- 50; 3- 100, 1- 1000, 1- 2000.

Burettes according to NTD types 1- 2- 25; 3- 2- 25; 6- 2- 2; 6- 2- 5; 7- 2- 3; 7- 2- 10.

Pipettes 2-1-50 , 2-3-50 according to NTD.

Flasks 1 - 100 - 2, 2 - 100 - 2, 1 - 1000 - 2, 2 - 1000 - 2 by GOST1770.

Glass cup evaporating in accordance with GOST 9147.

Electric stove with a closed spiral of any type.

Cups for weighing (b yuk c s) according to GOST 25336.

Funnel heating.

ChPN hourglass stopwatch-5.

Flask (bottle) made of dark glass or painted black.

Putty knife.

Exicator according to GOST 25336.

Laboratory glass dropper according to GOST 25336.

Drying cabinet or muffle furnace.

Scaleslaboratory general purpose with weighing limit 200g not less than 2 th class.

Scales are technical.

Tubes l orca lion.

Alcohol-ethyl rectified according to GOST 18300.

Potassium hydroxide, x. h or h..,0, 05 mol/dm 3 alcoholic titrated solution.

calcium chloride 2- in one according to TU 6-09-5077 or calcium chloride according to specifications 6-09-4711.

Soda lime or ascarite.

Kaliifta l evo-sour (potassium biphta lat).

Acid-amber, x. h or h. according to GOST 6341.

Benzol according to GOST 5955 or GOST 9572. Xylene according to GOST 9410 or GOST 9949.

Toluol according to GOST 14710 or GOST 9880.

Alkaline blue6B, prepare as follows: 0, 8g alkali blue 6B is dissolved in 1000 cm 3 ethyl alcohol 96%-nogo, then add 1500cm 3 benzene until complete dissolution of the indicator. After adding benzene, the mixture is kept for 12h, then clear solution filter out.

Acid hydrochloric 0 , 1 mol/dm 3 .

It is allowed to use standard solution of hydrochloric acid prepared from fixanal.

indicator rosin yellow, 0.5% and aqueous solution.

Indicatorphenolphthalein according to specifications 6- 09-5360, 1% alcohol solution prepared according to GOST 4919.1.

Water distilled pH 5, 4-6, 6.

It is allowed to use reagents whose quality is not lower than those specified in the standard.

(Changed edition, Rev.№1, 2).

2. PREPARATION FOR THE TEST

2.1a. Sampling is carried out according to GOST 2517.

(Introduced additionally, Rev. No. 1).

2. 1. For the preparation of titrated solutions, freshly distilled ethyl alcohol is used. The distillation of alcohol is carried out in a flask with a capacity 1000cm 3 with dephlegmator.

2. 2. Cooking 85 % ethanol solution

2. 2.1. Mixed 89 cm 3 ethyl alcohol and 11 cm 3 distilled water.

2. 3. Preparation of indicators

2. 3.1.For cooking 0, 5% aqueous solution no indicator t pink yellow 0, 5g indicator is dissolved in 100 cm 3 distilled water.

2. 3. 2. (Deleted, Rev. No. 2).

2. 4. To establish a titraalcoholic solution of potassium hydroxide, recrystallized acidic phtha is used. levo-acid s and potassium (biphthalate potassium) or succinic acid.

2. 4.1. 70 g bift l potassium ate is dissolved in 200 cm 3 distilled hot water. Recrystallization is carried out at a temperature not lower than 25°C because crystals form at lower temperatures. trifta l Potassium ata is a more acidic salt. The resulting crystals are dried to constant weight at ( 105± 5) °С.

2. 4. 2. 100G succinic acid dissolve in boiling 165ml of distilled water, the solution is filtered through a heated funnel. After cooling the solution, the crystals are filtered on a suction funnel and again perechrista lizov yva yu m. The crystals are dried at ( 105±5 )°С to constant mass.

2. 4. 3. Recrystallized potassium biphthalate and succinic acid are placed in a bottle s and stored in a desiccator. Before each establishment of the titer, potassium biphthalate and succinic acid are dried 1 h at (105 ± 5) °С .

2. 5. Preparation of 0.05 mol / dm 3 alcohol solution of potassium hydroxide.

2. 5. 1. 3g of crystalline potassium hydroxide is weighed with an error of not more than 0.1 g, dissolved in 1000 cm 3 ethyl alcohol. The resulting solution is thoroughly mixed and kept for at least 24h in a dark place.

The settled clear solution is separated from the precipitate by decantation into a burette bottle or a bottle with a dark glass stopper or painted black.

The buret should be protected by a soda lime or ascarite tube.

2. 5. 2. The titer of a solution of potassium hydroxide is set according to bift potassium lata.

It is allowed, in the absence of potassium biphthalate, to set the titer for succinic acid.

2. 5. 3. In a conical flask with a capacity 250 cm 3 place 0.05 - 0.07 g of potassium biphthalate or succinic acid, weighed with an error of not more than 0, 0002g, and dissolve them in 50cm 3 freshly boiled distilled water, add 3 - 4dropphenolphthalein and titrated 0.05 mol / dm 3 potassium hydroxide solution with continuous stirring until a pink color appears.

The color must be stable without agitation for 30With.

(Changed edition, Rev. No. 2).

2. 5. 4. The titer of potassium hydroxide solution (T) in mg/s m 3 calculated according to the formula

where 56 , 11-e equivalent mass of potassium hydroxide, G;

m - weight of bift l a t and potassium or succinic acid, g;

E- equivalent mass of potassium biphthalate or succinic acid, respectively equal to 204.23 and 59.04 g;

V 1 - volume 0 , 05 mol/dm 3 potassium hydroxide solution used for titration of the mass of potassium biphthalate or succinic acid, cm 3 .

The result of the titer determination is taken as the arithmetic mean of at least three parallel determinations, the discrepancy between which does not exceed 0.03 mg.

The titer solution is checked at least once every two weeks.

2. 6. Sample preparation

2. 6. 1. A sample of the oil product is thoroughly mixed by shaking for 5min in a bottle filled with no more than 3/4 of its volume.

Viscous and paraffinists e petroleum products are preheated to 60°C.

(Changed edition, Rev. No. 1).

2. 6. 2. When testing greases, the surface of the tested grease is removed and discarded. upper layer. Then, in several places (at least three), samples are taken in approximately equal quantities at a distance of at least 5mm from the walls of the vessel, placed in a porcelain cup and thoroughly mixed.

3. CARRYING OUT THE TEST

3.1. To test light products, samples are taken from 50 to 100 cm3 samples. The mass of the sample for testing oils is determined according to Table. .

Table 1

When testing greases in a conical flask with a capacity of 250cm 3 place 5-8 g of the test product, weighed with an error of not more than 0.01

3. 2. Pour into another conical flask 50cm 3 85% ethyl alcohol and reflux with water or air for 5min. Add to boiled alcohol 8 - 10 drops (0.25 cm 3) of no indicator pink yellow neutralized hot with continuous stirring 0, 05n. alcoholic solution of potassium hydroxide until the first change from yellow to green.

3. 3. Defineacidity

The test sample is poured into a flask with neutralized hot alcohol and boiled for5min (exactly) under reflux with constant stirring.

If the contents of the flask are still green after boiling, stop the test and consider that the test sample is not acidic.

In the event of a change in color, the mixture in a hot state is titrated with an alcoholic solution of potassium hydroxide with continuous vigorous stirring until a change in yellow (oryellow with shades) color of the alcohol layer or a mixture of green (or greenWith shades). The color must be stable without agitation for 30 s.

Titration is carried out in a hot state quickly in order to avoide influence carbon dioxide contained in the air.

3. 4. Definenie acid number

A sample of the test product is placed in a conical flask in the amount indicated in paragraph. Add when shaking at least 40 cm 3 alkaline blue 6B complete dissolution of the sample. Then the contents of the flask are titrated with light shaking with an alcoholic solution of potassium hydroxide until the blue color changes to red or blue tint to red.

In parallel, a control experiment is carried out without the test sample, using the same amount of alkali blue solution. 6B.

In case of poor dissolution of the sample, the contents of the flask are refluxed for5min with constant stirring.

When testing the lubricant, the boiling time is increased by5min after complete dissolution.

It is allowed to carry out the determination of acidtn th next m way: neutralized hot alcohol, prepared as indicated in paragraph , is poured into the flask with the product to be tested. The contents of the flask are refluxed for 5min with constant stirring. The hot mixture is titrated with an alcoholic solution of potassium hydroxide, as indicated in P. .

In the presence of a green (or green with shades) color in the mixture, titration with a solution of potassium hydroxide is not performed. In this case, there are no organic acids in the tested oil product.

In case of disagreement in assessing the quality of petroleum products, the determination of the acid number is carried out using an alkaline blue indicator. 6B.

(Changed edition, Rev. No. 1, 2).

3. 5. (Deleted, Rev. No. 1 ).

4. PROCESSING THE RESULTS

4. 1. Acidity of the tested oil product (K) in m g KOH 100 cm 3 calculated according to the formula

where V 2 - volume 0 , 05 mol/dm 3 potassium hydroxide solution used for titration, cm 3 ;

T- t itr 0.05 mol / dm 3 potassium hydroxide solution, mg/cm 3 ;

V 0 - the volume of the test sample, cm 3 ;

100 - conversion factor to 100 cm 3 products.

(Changed edition, Rev. No. 1).

4. 2. Acid number of the test sample (K 1 ) in mg KOH/g using alkaline blue as an indicator is calculated by the formula

where V 3 - volume 0 , 05 mol/dm 3 alcohol solution of potassium hydroxide used for titration, cm 3 ;

V 4 - volume 0.05 mol / dm 3 alcohol solution of potassium hydroxide,spent on the control experiment, cm 3 ;

T- caption 0 , 05 mol/dm 3 alcohol solution of potassium hydroxide, mg/cm 3 ;

m 1 - weight of the sample, g.

The acid number of the test sample (K 2) in m gKOH/ g when used as an indicator of nitrosis in new yellow is calculated by the formula

where V 3 - volume 0 , 05 mol/dm 3 alcohol solution of potassium hydroxide used for titration, cm 3 ;

T - t itr 0.05 mol / dm 3 alcohol solution of potassium hydroxide, mg / s m 3;

m 1 - weight of the sample, g.

(Changed edition, Rev. No. 1).

4. 3. The test result is taken as the arithmetic mean e results of two parallel determinations.

4. 3. 1.Two test results obtained by one laboratory assistant are recognized as reliable with a confidence level 0, 95%, if the discrepancy between them does not exceed the values ​​indicated in Table. , .

(Treason n new edition, Rev. No. 1, 2).

4. 3. 2. Two test results obtained in two different laboratories are recognized as reliable with a confidence level 95%, if the discrepancy between them does not exceed the values ​​indicated in Table. and .

table 2

GOST 5985-79

INTERSTATE NY STANDARD

PETROLEUM PRODUCTS

METHOD FOR DETERMINING ACIDITY
AND ACID NUMBER

IPK STANDARDS PUBLISHING HOUSE
Moscow

INTERSTATE STANDARD

Introduction date 01. 01. 80

This standard applies to light petroleum products (leaded and unleaded gasolines, naphthas,kerosene, diesel fuel, jet fuel), unalloyed e oils, special oils and hydrocarbon greases and establishes methods for the determination of acidity and acid number.

The essence of the method lies in the titration of acidic compounds of the test product with an alcohol solution of potassium hydroxide in the presence of a color indicator and the determination of acidity for light oil products, expressed in mg KOH / 100cm 3, for oils and greases - acid number, expressed in mg KOH / g.

1. EQUIPMENT, REAGENTS AND MATERIALS

Flasks Kn -1 - 100- 29/ 32 TC, Kn -2-100- 34 THS, Kn- 2-100-22 THS, Kn -1- 250- 29/ 32 TS, Kn- 2- 250- 34, K GU- 2- 1-1000-29/32 TS, KGU-2-2-1000-34 THS according to GOST 25336.

Christmas tree dephlegmator not less than 400mm.

Refrigerators XT P - 1- 400- 14/ 23, ХШ -1- 400- 29/ 32 ХС, ХШ- 3- 400 THS according to GOST 25336 or air cooler, or glass tubes, length 700 - 750mm with inner diameter 10 - 12 mm.

Cylinders according to GOST 1770 types 1- 50; 1- 100; 3- 50; 3- 100, 1- 1000, 1- 2000.

Burettes according to NTD types 1- 2- 25; 3- 2- 25; 6- 2- 2; 6- 2- 5; 7- 2- 3; 7- 2- 10.

Pipettes 2-1-50 , 2-3-50 according to NTD.

Flasks 1 - 100- 2, 2- 100- 2, 1- 1000- 2, 2- 1000- 2according to GOST 1770.

Evaporating glass or cup according to GOST 9147.

Electric stove with a closed spiral of any type.

Weighing cups (b yuk c s) according to GOST 25336.

Funnel with heating.

Stopwatch or hourglass CPN-5.

Flask (bottle) made of dark glass or painted black.

Putty knife.

Desiccator according to GOST 25336.

Laboratory glass dropper according to GOST 25336.

Drying cabinet or muffle furnace.

General purpose laboratory scales with a weighing limit 200g not less than 2 -th class of accuracy.

Scales are technical.

Tube x l orca lion.

Rectified ethyl alcohol according to GOST 18300.

Potassium hydroxide, x. h or h..,0, 05 mol/dm 3 alcoholic titrated solution.

Calcium chloride 2- in one according to TU 6-09-5077 or calcium chloride according to specifications 6-09-4711.

Soda lime or ascarite.

Potassium fta l evo-sour (potassium biphtalate).

Succinic acid, x. h or h. according to GOST 6341.

Benzene according to GOST 5955 or GOST 9572. Xylene according to GOST 9410 or GOST 9949.

Toluene according to GOST 14710 or GOST 9880.

Alkaline blue6B, prepare as follows: 0, 8g alkali blue 6B is dissolved in 1000 cm 3 ethyl alcohol 96%-nogo, then add 1500 cm 3 benzene until the indicator is completely dissolved. After adding benzene, the mixture is kept for 12h, then the clear solution is filtered off.

Hydrochloric acid 0 , 1 mol/dm 3 .

It is allowed to use a standard solution of hydrochloric acid prepared from fixanal.

None indicator pink yellow, 0.5% and aqueous solution.

Indicator phenolphthalein according to specifications 6- 09-5360, 1% alcohol solution prepared in accordance with GOST 4919.1.

Distilled water pH 5, 4-6, 6.

It is allowed to use reagents whose quality is not lower than those specified in the standard.

(Revised edition, Rev.№ 1, 2).

2. PREPARATION FOR THE TEST

2.1a. Sampling is carried out according to GOST 2517.

(Introduced additionally, Rev. No. 1).

2. 1. Freshly distilled ethyl alcohol is used to prepare titrated solutions. The distillation of alcohol is carried out in a flask with a capacity of 1000 cm 3 with dephlegmator.

2. 2. Cooking 85 % ethanol solution

2. 2.1. Mixed 89 cm 3 ethyl alcohol and 11 cm 3 distilled water.

2. 3. Preparation of indicators

2. 3.1.For cooking 0, 5% aqueous solution of the indicator t pink yellow 0, 5g of the indicator is dissolved in 100 cm 3 distilled water.

2. 3. 2. (Deleted, Rev. No. 2).

2. 4. To establish the titer of an alcoholic solution of potassium hydroxide, recrystallized acidic hydroxide is used. levo-acid s and potassium (potassium biphthalate) or succinic acid.

2. 4.1. 70 g bift l potassium ate is dissolved in 200 cm 3 distilled hot water. Recrystallization is carried out at a temperature not lower than 25°C because crystals form at lower temperatures. trifta l potassium ata is a more acidic salt. The resulting crystals are dried to constant weight at ( 105 ± 5) °С.

2. 4. 2. 100g of succinic acid is dissolved by boiling in 165ml of distilled water, the solution is filtered through a heated funnel. After cooling the solution, the crystals are filtered on a suction funnel and again perechrista lizov yva yu m. The crystals are dried at ( 105±5 ) °С to constant mass.

2. 4. 3. Recrystallized potassium biphthalate and succinic acid are placed in a bottle s and stored in a desiccator. Before each establishment of the titer, potassium biphthalate and succinic acid are dried 1 h at (105 ± 5) °С .

2. 5. Preparation of 0.05 mol / dm 3 alcohol solution of potassium hydroxide.

2. 5. 1. 3g of crystalline potassium hydroxide is weighed with an error of not more than 0.1 g, dissolved in 1000 cm 3 ethyl alcohol. The resulting solution is thoroughly mixed and kept for at least 24h in a dark place.

The settled clear solution is separated from the precipitate by decantation into a burette bottle or a bottle with a dark glass stopper or painted black.

The burette should be protected by a soda lime or ascarite tube.

2. 5. 2. The titer of a solution of potassium hydroxide is set according to bift potassium lata.

It is allowed, in the absence of potassium biphthalate, to set the titer for succinic acid.

2. 5. 3. In a conical flask with a capacity 250 cm 3 place 0.05 - 0.07 g of potassium biphthalate or succinic acid, weighed with an error of not more than 0, 0002g, and dissolve them in 50 cm 3 freshly boiled distilled water, add 3 - 4drops of phenolphthalein and titrate 0.05 mol / dm 3 potassium hydroxide solution with continuous stirring until a pink color appears.

The color must be stable without agitation for 30With.

(Changed edition, Rev. No. 2).

2. 5. 4. The titer of potassium hydroxide solution (T) in mg/s m 3 calculated according to the formula

where 56 , 11-e equivalent mass of potassium hydroxide, G;

m - weight of bift l a t and potassium or succinic acid, g;

E- equivalent mass of potassium biphthalate or succinic acid, respectively equal to 204.23 and 59.04 g;

V 1 - volume 0 , 05 mol/dm 3 potassium hydroxide solution used for titration of the mass of potassium biphthalate or succinic acid, cm 3 .

The result of the titer determination is taken as the arithmetic mean of at least three parallel determinations, the discrepancy between which does not exceed 0.03 mg.

The titer of the solution is checked at least once every two weeks.

2. 6. Sample preparation

2. 6. 1. The sample of the oil product is thoroughly mixed by shaking for 5min in a flask filled with no more than 3/4 of its volume.

Viscous and waxys e oil products are preheated to 60°C.

(Changed edition, Rev. No. 1).

2. 6. 2. When testing greases, the top layer is removed from the surface of the tested grease and discarded. Then, in several places (at least three), samples are taken in approximately equal quantities at a distance of at least 5mm from the walls of the vessel, placed in a porcelain cup and mixed thoroughly.

3. CARRYING OUT THE TEST

3.1. For testing light oil products are taken from 50 to 100 cm3 samples. The mass of the sample for testing oils is determined according to table..

Table 1

When testing greases in a conical flask with a capacity of 250cm 3 placed 5 - 8 g of the test product, weighed with an error of not more than 0.01

3. 2. Pour into another conical flask 50 cm 3 85% ethyl alcohol and reflux with water or air for 5min. Add to boiled alcohol 8 - 10 drops (0.25 cm 3) of no indicator pink yellow and neutralized while hot with continuous stirring 0, 05n. alcoholic solution of potassium hydroxide until the first change from yellow to green.

3. 3. Defineacidity

The test sample is poured into a flask with neutralized hot alcohol and boiled for5min (exactly) under reflux with constant stirring.

If the contents of the flask are still green after boiling, the test is terminated and the test sample is considered to be acidic.

In the event of a change in color, the mixture is titrated in a hot state with an alcoholic solution of potassium hydroxide with continuous vigorous stirring until a change in yellow (oryellow with shades) coloring the alcohol layer or mixture in green (or greenWith shades). The color must be stable without agitation for 30 s.

Titration is carried out in a hot state quickly in order to avoide the effect of carbon dioxide in the air.

3. 4. Definenie acid number

A sample of the test product is placed in a conical flask in the amount specified in paragraph 1.. Add with shaking at least 40 cm 3 alkaline blue 6B until complete dissolution of the sample. Then the contents of the flask are titrated with slight shaking with an alcoholic solution of potassium hydroxide until the blue color changes to red or the blue tint to red.

In parallel, a control experiment is carried out without the test sample, using the same amount of alkaline blue solution. 6B.

In case of poor dissolution of the sample, the contents of the flask are refluxed for5min with constant stirring.

When testing the lubricant, the boiling time is increased by5min after complete dissolution.

It is allowed to carry out the determination of acidtn th next m way: neutralized hot alcohol, prepared as indicated in paragraph , is poured into the flask with the product to be tested. The contents of the flask are refluxed for 5min with constant stirring. The mixture is titrated while hot with an alcoholic solution of potassium hydroxide, as indicated in P. .

If there is a green (or green with shades) color in the mixture, titration with a solution of potassium hydroxide is not performed. In this case, there are no organic acids in the tested oil product.

In case of disagreement in assessing the quality of petroleum products, the determination of the acid number is carried out using an alkaline blue indicator. 6B.

(Changed edition, Rev. No. 1, 2).

3. 5. (Deleted, Rev. No. 1).

4. PROCESSING THE RESULTS

4. 1. The acidity of the tested oil product (K) in m g KOH per 100 cm 3 calculated according to the formula

where V 2 - volume 0 , 05 mol/dm 3 potassium hydroxide solution used for titration, cm 3 ;

T- t itr 0.05 mol / dm 3 potassium hydroxide solution, mg/cm 3 ;

V 0 - the volume of the test sample, cm 3 ;

100 - conversion factor to 100 cm 3 products.

(Changed edition, Rev. No. 1).

4. 2. The acid number of the test sample (K 1 ) in mg KOH/g using alkaline blue as indicator is calculated by the formula

where V 3 - volume 0 , 05 mol/dm 3 alcohol solution of potassium hydroxide used for titration, cm 3 ;

V 4 - volume 0.05 mol / dm 3 alcohol solution of potassium hydroxide,spent on the control experiment, cm 3 ;

T- caption 0 , 05 mol/dm 3 alcohol solution of potassium hydroxide, mg/cm 3 ;

m 1 - weight of the sample, g.

The acid number of the test sample (K 2) in m g KOH/g when used as an indicator of nitrosis in new yellow is calculated by the formula

where V 3 - volume 0 , 05 mol/dm 3 alcohol solution of potassium hydroxide used for titration, cm 3 ;

T - t itr 0.05 mol / dm 3 alcohol solution of potassium hydroxide, mg / s m 3;

m 1 - weight of the sample, g.

(Changed edition, Rev. No. 1).

4. 3. The test result is taken as the arithmetic mean e results of two parallel determinations.

4. 3. 1.Two results of determinations obtained by one laboratory assistant are recognized as reliable with a confidence level 0, 95%, if the discrepancy between them does not exceed the values ​​indicated in Table. , .

(Treason n edition, Rev. No. 1, 2).

4. 3. 2. Two test results obtained in two different laboratories are considered reliable with a confidence level 95%, if the discrepancy between them does not exceed the values ​​indicated in Table. and .

table 2

TU 6-09-5360-88*

________________
* Specifications mentioned hereinafter are not given. See the link for more information. - Database manufacturer's note.

6. The limitation of the validity period was removed by the Decree of the State Standard of the USSR of December 28, 1991 N 2259

7. EDITION (June 2009) with Amendments 1, 2, approved in April 1984, December 1991 (IUS 8-84, 4-92)


AMENDMENTS HAVE BEEN MADE, published in IUS N 11, 2011 and IUS N 3, 2016

Amendments made by database manufacturer

This International Standard applies to light petroleum products (leaded and unleaded gasolines, naphthas, kerosenes, diesel fuels, jet fuels), unalloyed oils, specialty oils and hydrocarbon greases and specifies methods for the determination of acidity and acid number.

The essence of the method consists in titration of acidic compounds of the test product with an alcoholic solution of potassium hydroxide in the presence of a color indicator and determination of acidity for light oil products, expressed in mg KOH / 100 cm3, for oils and lubricants - acid number, expressed in mg KOH / g.

1. EQUIPMENT, REAGENTS AND MATERIALS

Flasks Kn-1-100-29/32 TS, Kn-2-100-34 THS, Kn-2-100-22 THS, Kn-1-250-29/32 TS, Kn-2-250-34, KGU -2-1-1000-29/32 TS, KGU-2-2-1000-34 THS according to GOST 25336.

Christmas tree dephlegmator not less than 400 mm long.

Refrigerators ХТП-1-400-14/23, ХШ-1-400-29/32 ХС, ХШ-3-400-ТХС according to GOST 25336 or air cooler or glass tubes 700-750 mm long with inner diameter 10-12 mm.

Cylinders according to GOST 1770 types 1-50; 1-100; 3-50; 3-100, 1-1000, 1-2000.

Burettes according to NTD types 1-2-25; 3-2-25; 6-2-2; 6-2-5; 7-2-3; 7-2-10.

Pipettes 2-1-50, 2-3-50 according to NTD.

Flasks 1-100-2, 2-100-2, 1-1000-2, 2-1000-2 according to GOST 1770.

Evaporating glass or cup according to GOST 9147.

Electric stove with a closed spiral of any type.

Cups for weighing (bottle bags) in accordance with GOST 25336.

Funnel with heating.

Stopwatch or hourglass ChPN-5.

Flask (bottle) made of dark glass or painted black.

Putty knife.

Desiccator according to GOST 25336.

Laboratory glass dropper in accordance with GOST 25336.

Drying cabinet or muffle furnace.

General purpose laboratory scales with a weighing limit of 200 g, not lower than the 2nd accuracy class.

Scales are technical.

The tube is calcium chloride.

Rectified ethyl alcohol according to GOST 18300.

Potassium hydroxide, chemically pure or analytical grade, 0.05 mol/dm alcoholic titrated solution.

Calcium chloride 2-water according to TU 6-09-5077 or calcium chloride according to TU 6-09-4711.

Soda lime or ascarite.

Potassium phthalate acid (potassium biphthalate).

Succinic acid, chemically pure or h.d.a. according to GOST 6341.

Benzene according to GOST 5955 or GOST 9572. Xylene according to GOST 9410 or GOST 9949.

Toluene according to GOST 14710 or GOST 9880.

Alkaline blue 6B is prepared as follows: 0.8 g of alkali blue 6B is dissolved in 1000 ml of ethyl alcohol 96%, then 1500 ml of benzene are added until the indicator is completely dissolved. After the addition of benzene, the mixture was kept for 12 hours, then the clear solution was filtered off.

Hydrochloric acid 0.1 mol/dm.

It is allowed to use a standard solution of hydrochloric acid prepared from fixanal.

Indicator nitrosine yellow, 0.5% aqueous solution.

Indicator phenolphthalein according to TU 6-09-53608, 1% alcohol solution, prepared according to GOST 4919.1.

Distilled water pH 5.4-6.6.

It is allowed to use reagents whose quality is not lower than those specified in the standard.

2. PREPARATION FOR THE TEST

2.1a. Sampling is carried out according to GOST 2517.

(Introduced additionally, Rev. N 1).

2.1. Freshly distilled ethyl alcohol is used to prepare titrated solutions. The distillation of alcohol is carried out in a flask with a capacity of 1000 ml with a reflux condenser.

2.2. Preparation of 85% solution of ethyl alcohol.

2.2.1. Mix 89 ml of ethyl alcohol and 11 ml of distilled water.

2.3. Preparation of indicators

2.3.1. To prepare a 0.5% aqueous solution of the nitrosine yellow indicator, 0.5 g of the indicator is dissolved in 100 ml of distilled water.

2.3.2. (Deleted, Rev. N 2).

2.4. To establish the titer of an alcoholic solution of potassium hydroxide, recrystallized acid potassium phthalate (potassium biphthalate) or succinic acid is used.

2.4.1. 70 g of potassium biphthalate are dissolved in 200 ml of distilled hot water. Recrystallization is carried out at a temperature not lower than 25°C, since crystals of potassium triphthalate, a more acidic salt, are formed at a lower temperature. The resulting crystals are dried to constant weight at (105±5)°C.

2.4.2. 100 g of succinic acid is dissolved at boiling in 165 ml of distilled water, the solution is filtered through a heated funnel. After cooling the solution, the crystals are filtered off on a suction funnel and recrystallized again. The crystals are dried at (105±5)°C to constant weight.

2.4.3. Recrystallized potassium biphthalate and succinic acid are placed in bottles and stored in a desiccator. Before each establishment of the titer, potassium biphthalate and succinic acid are dried for 1 hour at (105±5)°C.

2.5. Preparation of 0.05 mol/dm alcoholic solution of potassium hydroxide.

2.5.1. 3 g of crystalline potassium hydroxide is weighed with an error of not more than 0.1 g, dissolved in 1000 ml of ethyl alcohol. The resulting solution is thoroughly mixed and incubated for at least 24 hours in a dark place.

The settled clear solution is separated from the precipitate by decantation into a burette bottle or a bottle with a dark glass stopper or painted black.

The burette should be protected by a soda lime or ascarite tube.

2.5.2. The titer of potassium hydroxide solution is determined by potassium biphthalate.

It is allowed, in the absence of potassium biphthalate, to set the titer for succinic acid.

2.5.3. 0.05-0.07 g of potassium biphthalate or succinic acid, weighed with an error of not more than 0.0002 g, are placed in a conical flask with a capacity of 250 ml, and dissolved in 50 ml of freshly boiled distilled water, 3-4 drops of phenolphthalein are added and titrated with 0 05 mol/dm potassium hydroxide solution with continuous stirring until a pink color appears.

The color should be stable without agitation for 30 s.

2.5.4. The titer of potassium hydroxide solution in mg/cm is calculated by the formula

(Amendment. IUS N 11-2011)

where 56.11 is the equivalent mass of potassium hydroxide, g;

- mass of potassium biphthalate or succinic acid, g;

- equivalent mass of potassium biphthalate or succinic acid, respectively equal to 204.23 and 59.04 g;

- the volume of 0.05 mol / dm of potassium hydroxide solution used for titration of the mass of potassium biphthalate or succinic acid, see.

The result of the titer determination is taken as the arithmetic mean of at least three parallel determinations, the discrepancy between which does not exceed 0.03 mg.

The titer of the solution is checked at least once every two weeks.

2.6. Sample preparation

2.6.1. The oil product sample is thoroughly mixed by shaking for 5 minutes in a flask filled with no more than its volume.

Viscous and paraffinic oils are preheated to 60°C.

(Changed edition, Rev. N 1).

2.6.2. When testing greases, the top layer is removed from the surface of the tested grease and discarded. Then, in several places (at least three), samples are taken in approximately equal amounts at a distance of at least 5 mm from the walls of the vessel, placed in a porcelain cup and thoroughly mixed.

3. CARRYING OUT THE TEST

3.1. To test light oil products, samples from 50 to 100 cm3 are taken. The mass of the oil test sample is determined according to Table 1.

Table 1

When testing greases, 5-8 g of the test product, weighed with an error of not more than 0.01 g, is placed in a conical flask with a capacity of 250 cm3.

3.2. Pour 50 ml of 85% ethanol into another conical flask and reflux with water or air for 5 minutes. Add 8-10 drops (0.25 cm) of nitrosine yellow indicator to the boiled alcohol and neutralize in the hot state with continuous stirring 0.05 N. alcoholic solution of potassium hydroxide until the first change from yellow to green.

3.3. Determination of acidity

The test sample is poured into a flask with neutralized hot alcohol and refluxed for 5 minutes (exactly) with constant stirring.

If the contents of the flask are still green after boiling, the test is terminated and the test sample is considered to be acidic.

If the color changes, the hot mixture is titrated with an alcoholic solution of potassium hydroxide with continuous vigorous stirring until the yellow (or yellow with tints) color of the alcoholic layer or the mixture changes to green (or green with tints). The color should be stable without agitation for 30 s.

Titration is carried out in a hot state quickly to avoid the influence of carbon dioxide contained in the air.

3.4. Determination of acid number

A sample of the test product is placed in a conical flask in the amount specified in paragraph 3.1. Add with shaking at least 40 ml of alkaline blue 6B until the sample is completely dissolved. Then the contents of the flask are titrated with slight shaking with an alcoholic solution of potassium hydroxide until the blue color changes to red or the blue tint to red.

In parallel, a control experiment is carried out without the test sample, using the same amount of alkaline blue 6B solution.

In case of poor dissolution of the sample, the contents of the flask are refluxed for 5 min with constant stirring.

When testing the lubricant, the boiling time is increased by 5 minutes after its complete dissolution.

It is allowed to carry out the determination of the acid number as follows: neutralized hot alcohol, prepared as indicated in paragraph 3.2, is poured into the flask with the test product. The contents of the flask are refluxed for 5 min with constant stirring. The hot mixture is titrated with an alcoholic solution of potassium hydroxide, as indicated in paragraph 3.3.

If there is a green (or green with shades) color in the mixture, titration with a solution of potassium hydroxide is not performed. In this case, there are no organic acids in the tested oil product.

In case of disagreement in assessing the quality of petroleum products, the determination of the acid number is carried out using an alkaline blue indicator 6B.

(Changed edition, Rev. N 1, 2).

3.5. (Excluded, Rev. N 1).

4. PROCESSING THE RESULTS

4.1. The acidity of the tested oil product in mg KOH per 100 cm is calculated by the formula

where is the volume of 0.05 mol/dm of potassium hydroxide solution used for titration, cm;

- titer of 0.05 mol/dm potassium hydroxide solution, mg/cm;

- the volume of the test sample, cm;

100 - conversion factor per 100 cm of product.

4.2. The acid number of the test sample () in mg KOH/g, using alkaline blue as the indicator, is calculated by the formula

- the volume of 0.05 mol/dm alcoholic solution of potassium hydroxide, spent on the control experiment, cm;


- weight of the sample, g.

The acid number of the test sample () in mg KOH/g, using nitrosine yellow as an indicator, is calculated by the formula

where is the volume of a 0.05 mol/dm alcoholic solution of potassium hydroxide used for titration, cm;

- titer of 0.05 mol/dm alcoholic solution of potassium hydroxide, mg/cm;

- weight of the sample, g.

4.1-4.2. (Changed edition, Rev. N 1).

4.3. The test result is taken as the arithmetic mean of the results of two parallel determinations.

4.3.1. Two test results obtained by one laboratory assistant are recognized as reliable at a confidence level of 0.95%, if the discrepancy between them does not exceed the values ​​indicated in tables 2, 3.

(Changed edition, Rev. N 2).

4.3.2. Two test results obtained in two different laboratories are recognized as reliable at a confidence level of 95%, if the discrepancy between them does not exceed the values ​​indicated in Table. 2 and 3.

table 2

(Amendment. IUS N 3-2016).

Table 3

The test results are rounded to the second decimal place.

4.3.1-4.3.2. (Changed edition, Rev. N 1).

APPENDIX. (Excluded, Rev. N 2).

Electronic text of the document
prepared by Kodeks JSC and verified against:
official publication
M.: Standartinform, 2009

Revision of the document, taking into account
changes and additions prepared
JSC "Kodeks"