STATE STANDARD OF THE USSR UNION
DIESEL FUEL
METHOD FOR DETERMINING THE LIMITING TEMPERATURE
FILTERABILITY ON A COLD FILTER
COMMITTEE FOR STANDARDIZATION AND METROLOGY OF THE USSR
Moscow
STATE STANDARD OF THE USSR UNION
Date entered 01.01.93
This standard establishes a method for determining the maximum filterability temperature on a cold filter for diesel and household heating fuels intended for the national economy and for export.
Additions reflecting the needs of the national economy are in italics.
The method applies to diesel fuels without additives and with additives, as well as to fuels used in home heating systems.
Limit filterability temperature (cold filter) - the highest temperature at which a given volume of fuel will not flow through a standardized filter unit for a specified time, during cooling under standardized conditions.
The method consists of gradually cooling the test fuel at intervals of 1° C and moaning it through a wire filtration mesh at a vacuum of 1961 Pa (200 mm water column).
The determination is carried out to the temperature at which the paraffin crystals released from the solution onto the filter cause the flow to stop or slow down to such an extent that the pipette filling time exceeds 60 s, or the fuel does not flow completely back into the measuring vessel.
5.1. White spirit, boiling between 60 - 80 °C.
5.2. Acetone.
Solvents: nefras C 50/170 according to GOST 8505 or petroleum ether according to TU 6-021244;
Paper filters "White tape".
For testing, equipment according to drawing is used. , which includes:
wall thickness (1.25 ± 0.25) mm and height (120 ± 5) mm, with a limiting ring mark at a height corresponding to a volume of 45 cm 3.
Measuring vessels of the required dimensions can be selected from vessels that meet the requirements of the GOST 20287 method.
6.2. Metal casing (Fig. ) - brass, cylindrical, waterproof, flat-bottomed with an internal diameter of (45 ± 0.25) mm, an external diameter of (48 ± 0.25) mm and a height of 115 mm. Use as a water bath.
6.3. Insulating ring (Fig. ) - made of oil-resistant material, which is placed at the bottom of the casing (item. ) to isolate the measuring vessel from the bottom. It must fit exactly to the casing and must be (6) mm thick.
6.4. Two gaskets (3 and 6) 5 mm thick, made of oil-resistant material. The gaskets must be accurately fitted to the measuring vessel and loosely to the casing. The use of partial rings, each with a radial gap of 2 mm, allows the gaskets to be adapted to changes in the diameter of the measuring vessel. The gaskets and insulating ring can be made as one piece (see drawing. ).
6.5. A support ring (Fig. ) made of oil-resistant material to secure the casing (Item ) in a stable vertical position in the cooling bath, as well as to maintain the plug (Item ) in a centered position. The ring can be modified to fit in a cooling bath.
6.6. Cork (damn) ) made of oil-resistant material, fitted to the measuring vessel and support ring. The stopper must have three holes: for a pipette (item.), thermometer (item. ) and release into the atmosphere. If a thermometer with wider temperature limits is used, the top of the plug may have a cut-out slot, which makes it possible to read the temperature on the thermometer (6.8) down to minus 30 °C. An indicator shall be attached to the top surface of the stopper to indicate the appropriate placement of the thermometer in relation to the bottom of the measuring vessel. To maintain the thermometer in the correct position, use a spring wire clamp,
6.7.1. Pipette (damn. ) made of transparent glass with a calibration mark at a height of (149 ± 0.5) mm from the base of the pipette, corresponding to a volume of (20.0 ± 0.2) cm 3. The pipette is connected to the filter.
6.7.2. Filter (fig. ) consists of the following parts:
brass body with a threaded hole in which a filter mesh is placed in a mandrel. The hole must be equipped with a gasket made of oil-resistant plastic. Inner diameter of the central tube (4.0 ± 0.1) mm;
brass nut to connect the top of the filter body to the bottom of the pipette to ensure a tight connection. An example of a correct connection is shown in Fig. ;
filter mesh with a diameter of 15 mm, made of bronze or stainless steel wire, with a nominal opening size of 45 microns. The nominal wire diameter should be 32 µm, and the dimensional error of individual cells should be as follows:
Each cell should not exceed the nominal size by more than 22 microns.
The average cell size should not exceed the nominal size by ±3.1 µm.
No more than 6% of cells can exceed the nominal size by more than 13 microns;
brass mandrel (Fig.), in which the filtration mesh (item) is clamped with a reinforcing ring squeezed into the holder. The diameter of the working part of the mesh should be (12) mm;
brass cylinder with external thread, which can be screwed into the housing hole (item) to press the mesh mandrel (item) through the gasket (item). At the bottom there should be four grooves that allow the sample to flow into the filtration apparatus.
6.8. Thermometers with measurement limits from minus 30 to plus 50 °C - to determine the maximum filterability temperature up to minus 30 ° C, from minus 80 to plus 20 °C - to determine the maximum filterability temperature below minus 30 °C, a thermometer for a cooling bath with temperature measurement limits from minus 80 to plus 20 °C.
Use thermometers that meet the requirements given in the appendix.
Note. Thermometers suitable for testing IP I C and 2C or ASTM 5C and 6C.
6.9. A cooling bath of any type, having a shape and dimensions suitable for placing a casing (item) in it in a stable vertical position to the required depth. The bathhouse must be equipped with a lid with holes to strengthen the support ring with the casing and the thermometer (item).
The casing can be firmly attached to the lid.
The temperature of the cooling bath must be maintained at the required level using a refrigerator or using an appropriate cooling mixture (section).
For different filterability limit temperatures, it is necessary to maintain the cooling bath temperatures given in the table. They are achieved either by using separate cooling baths or by adjusting the refrigerator. Using a refrigerator makes it possible to quickly change the temperature of the bath.
If several samples to be analyzed are placed in one large cooling bath, the distance between them must be at least 50 mm.
6.10. Glass stopcock, three-way, inclined, hole diameter 3 mm.
6.11. A vacuum pump or water pump with a power sufficient to provide a flow rate of 3 to 4 dm 3 / h in the vacuum regulator (item. ) during testing.
6.12. Vacuum regulator ( 17 ) (crap. ) - a glass bottle with a height of 350 - 400 mm, a capacity of 5 dm 3, filled to 3 / 4 water, sealed with a stopper with three holes for glass tubes. The two tubes should be short and should not be submerged in water. The third tube, with an internal diameter of approximately (6 ± 1) mm, should be long enough so that one end is immersed 200 mm in water and the other protrudes above the stopper.
The depth of the immersed part must be set in such a way as to obtain a pressure drop across the pressure gauge containing water of exactly 200 mm water column.
The installation is shown in Fig. .
Full set of equipment
1 - cooling bath; 2 - insulating ring; 3 - pad; 4 - filter; 5 - measuring vessel; 6 - pad; 7 - casing; 8 - support ring; 9 - cork; 10 - pipette; 11 - calibration mark (20 cm 3); 12 - three-way stopcock; 13 - U -shaped pressure gauge; 14 - water; 15 - connection with the atmosphere; 16 - connection to a vacuum pump; 17 - glass bottle (buffer container); 18 - water level
Crap. 1
6.13. Stopwatch with an error of 0.2
6.14. Semi-automatic device for determining the maximum filterability temperature of diesel fuels PAF according to TU 38.44710263-90, as well as other devices that provide the required testing accuracy.
6.15. Measuring vessels of the required dimensions can be selected from vessels that meet the requirements of the method according to GOST 20287.
6.16. Filter mesh made of stainless steel or copper alloy made of wire with a diameter of 0.028 to 0.032 mm and a number of cells from 17,000 to 20,500 per 1 cm 2 or No. 0045 N according to GOST 6613.
6.17. A cooling mixture consisting of solid carbon dioxide in accordance with GOST 12162 or solid carbon dioxide obtained by throttling liquid carbon dioxide into a dense bag and rectified ethyl alcohol in accordance with GOST 18300 or raw alcohol in accordance with GOST 131, or regenerated alcohol.
6.18. Thermometers type TINZ-1, TINZ-3, TN-8, GOST 400-80.
6.19. Mechanical stopwatch.
Brass casing
1 - silver solder
Crap. 2
Insulating ring and gaskets
1 - insulating ring; 2 - gaskets; 3a- stainless steel wires with a diameter of 2 mm
Crap. 3
Support ring
Crap. 4
Cork
1 - a slot that allows you to measure temperatures down to minus 30 °C; 2 - connection with the atmosphere; 3 - stainless steel clamp for securing the thermometer
Crap. 5
Pipette
1 - calibration mark
Crap. 6
Filter
and- thread designation according to GOST 9150-81 1 / - knurling; 2 - pipette tube; 3 - brass nut; 4 - gasket made of oil-resistant plastic, ring, diameter 5.28×1.78; 5 - brass body; 6 - gasket made of oil-resistant plastic, ring-shaped, diameter 12.42×1.78; 7 - filter mesh mandrel; 8 - brass cylinder with external thread
Crap. 7
Mandrel filter mesh
1 - mandrel body; 2 - reinforcing ring; 3 - filtration mesh
Crap. 8
A sample of the test fuel is filtered through dry filter paper (p.) at a temperature of at least 15 °C.
A fuel sample is taken according to TOST 2517. To remove mechanical impurities and water, the fuel is filtered through a “white tape” filter at a temperature no less than 15 °C above the cloud point.
Before each test, disassemble the filter (item) and wash its parts, as well as the measuring vessel (item), pipette (item) and thermometer (item) with a solvent, then rinse with acetone and dry with clean dry air. Check the cleanliness and dryness of all parts and casing. Check that the filtration mesh and connections are not damaged, and if necessary, replace them with new ones. Then the equipment is assembled as indicated in the devil. . Check the tightness of the threaded nut (p.) to see if there is a leak.
9.1. The insulating ring (item) is placed on the bottom of the casing (item).
9.2. If the gaskets (item) are not made as one piece with the insulating ring (item), they are placed at a distance of about 15 and 75 mm from the bottom of the measuring vessel (item).
9.3. The measuring vessel is filled with the test fuel to the mark corresponding to 45 cm 3 .
9.4. The measuring vessel is closed with a stopper containing a pipette with a filter (item) and a corresponding thermometer (item). When the expected filterability limit temperature is below minus 30 °C, a thermometer with lower temperature limits is used. The thermometer must not be changed during the test.
The equipment is installed in such a way that the lower part of the filter (item) is at the bottom of the measuring vessel; The thermometer is installed parallel to the pipette and in such a way that its lower end is (1.5 ± 0.2) mm from the bottom of the measuring vessel. The thermometer ball should not come into contact with either the wall of the measuring vessel or the filter.
9.5. The casing is placed vertically at a depth of (85 ± 2) mm in a cooling bath in which the temperature is maintained at minus (34 ± 0.5) °C.
9.6. The measuring vessel is placed in the housing in a stable vertical position.
9.7. With the shut-off valve open (item), connect the pipette to the vacuum unit (item , ) using flexible hoses connected to the tap (Fig. ). Turn on the vacuum and set the air flow so that U The -shaped pressure gauge showed a pressure drop of 200 mm water column during the entire test.
9.8. The determination begins immediately after placing the measuring vessel in the housing. If the cloud point of the sample is known, it is allowed to begin the determination at a time when the sample is cooled to a temperature that is at least 5 °C higher than the cloud point. In the first stage of cooling, you should always use a bath with a temperature of minus (34 ± 0.5) °C.
When the sample temperature reaches the appropriate value, install a shut-off valve (p.) so that the filter is connected to a vacuum, causing the fuel sample to be sucked through the filtration mesh into the pipette, and at the same time turn on the stopwatch. When the fuel reaches the mark on the pipette, stop the stopwatch and set the valve to the initial position so that the sample can flow into the measuring vessel.
If the time for fuel to be drawn in to the mark exceeds 60 s, then the determination is stopped and repeated with fresh test material, starting from a higher temperature.
9.9. Operation (p. ) is repeated after each decrease in sample temperature by 1 °C until the temperature at which flow through the filter stops is reached, or the pipette is not filled to the mark within 60 s.
Record the temperature at the start of the last filtration.
9.10. If after cooling according to paragraph. and or the sample fills the pipette to the mark in no longer than 60 s, but does not flow back into the measuring vessel after installing the stopcock (item. ) in the initial position, then it is necessary to record the temperature at which filtration begins.
9.11. If at a temperature of minus 20 °C the flow of fuel through the filter does not stop, further cooling is carried out in a cooling bath with a temperature of minus (51 ± 1) ° WITH or in a correspondingly switched refrigerator and repeat the operation (p. ) after each temperature decrease by 1 °C.
By changing the bath, quickly transfer the measuring vessel to a new casing placed in the second cooling bath, or by adjusting the refrigerator,
Transfer the kit as indicated in paragraph .
Record the temperature at the beginning of the last filtration with an accuracy of 1 °C (pp. - ) as the limiting temperature of filterability on a cold filter and make reference to this standard.
Processing the results.
The arithmetic mean of the results of two consecutive determinations, rounded to the nearest whole number, is taken as the result of the determination.
The accuracy of the method was obtained by statistical study of interlaboratory test results and is indicated in paragraphs. - (see note).
The discrepancy between successive test results obtained by the same operator on the same equipment under the same conditions on identical test material, when the test was performed correctly, exceeds the values indicated in Fig. , in one case out of twenty.
Two determination results obtained by one person in one laboratory are considered reliable (at a confidence level of 95%), if the discrepancy between them does not exceed 1 ° WITH.
The discrepancy between two independent results obtained by equal operators working in different laboratories on identical test material, when the test was performed correctly, exceeds the values presented in Fig. , in one case out of twenty.
Note Accuracy data presented oncrap , received under the program, in which both automatic and manual methods were used.
Two test results obtained in two different laboratories are considered reliable (at a confidence level of 95%) if the discrepancy between them does not exceed 2 °C.
Error in determining the maximum filterability temperature on a cold filter
Note. Below minus 35 °C the error is not established.
Crap. 9
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Temperature limits, °C |
Highest limit from -38 to +50 |
Lowest limit from -80 to +20 |
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A. Immersion, mm |
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Scale marks: |
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Division value, °C |
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Long mark, °C |
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Digital designation, °C |
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Maximum width, mm |
STATE STANDARD OF THE USSR UNION DIESEL FUEL METHOD FOR DETERMINING THE LIMITING TEMPERATURE GOST 22254-92COMMITTEE FOR STANDARDIZATION AND METROLOGY OF THE USSR STATE STANDARD OF THE USSR UNION Date entered 01.01.93 1. PURPOSEThis standard establishes a method for determining the maximum filterability temperature on a cold filter for diesel and household heating fuels intended for the national economy and for export. Additions reflecting the needs of the national economy are in italics. 2. AREA OF APPLICATIONThe method applies to diesel fuels without additives and with additives, as well as to fuels used in home heating systems. 3. DEFINITIONLimit filterability temperature (cold filter) - the highest temperature at which a given volume of fuel will not flow through a standardized filter unit for a specified time, during cooling under standardized conditions. 4. ESSENCE OF THE METHODThe method consists of gradually cooling the test fuel at intervals of 1° C and moaning it through a wire filtration mesh at a vacuum of 1961 Pa (200 mm water column). The determination is carried out to the temperature at which the paraffin crystals released from the solution onto the filter cause the flow to stop or slow down to such an extent that the pipette filling time exceeds 60 s, or the fuel does not flow completely back into the measuring vessel. 5. MATERIALS AND REAGENTS5.1. White spirit, boiling between 60 - 80 °C. 5.2. Acetone. Solvents: nefras C 50/170 according to GOST 8505 or petroleum ether according to TU 6-021244; Paper filters "White tape". 6. EQUIPMENTFor testing, equipment according to drawing is used. , which includes: wall thickness (1.25 ± 0.25) mm and height (120 ± 5) mm, with a limiting ring mark at a height corresponding to a volume of 45 cm 3. Measuring vessels of the required dimensions can be selected from vessels that meet the requirements of the GOST 20287 method. 6.2. Metal casing (Fig. ) - brass, cylindrical, waterproof, flat-bottomed with an internal diameter of (45 ± 0.25) mm, an external diameter of (48 ± 0.25) mm and a height of 115 mm. Use as a water bath. 6.3. Insulating ring (Fig. ) - made of oil-resistant material, which is placed at the bottom of the casing (item. ) to isolate the measuring vessel from the bottom. It must fit exactly to the casing and must be (6) mm thick. 6.4. Two gaskets (3 and 6) 5 mm thick, made of oil-resistant material. The gaskets must be accurately fitted to the measuring vessel and loosely to the casing. The use of partial rings, each with a radial gap of 2 mm, allows the gaskets to be adapted to changes in the diameter of the measuring vessel. The gaskets and insulating ring can be made as one piece (see drawing. ). 6.5. A support ring (Fig. ) made of oil-resistant material to secure the casing (Item ) in a stable vertical position in the cooling bath, as well as to maintain the plug (Item ) in a centered position. The ring can be modified to fit in a cooling bath. 6.6. Cork (damn) ) made of oil-resistant material, fitted to the measuring vessel and support ring. The stopper must have three holes: for a pipette (item.), thermometer (item. ) and release into the atmosphere. If a thermometer with wider temperature limits is used, the top of the plug may have a cut-out slot, which makes it possible to read the temperature on the thermometer (6.8) down to minus 30 °C. An indicator shall be attached to the top surface of the stopper to indicate the appropriate placement of the thermometer in relation to the bottom of the measuring vessel. To maintain the thermometer in the correct position, use a spring wire clamp, 6.7.1. Pipette (damn. ) made of transparent glass with a calibration mark at a height of (149 ± 0.5) mm from the base of the pipette, corresponding to a volume of (20.0 ± 0.2) cm 3. The pipette is connected to the filter. 6.7.2. Filter (fig. ) consists of the following parts: brass body with a threaded hole in which a filter mesh is placed in a mandrel. The hole must be equipped with a gasket made of oil-resistant plastic. Inner diameter of the central tube (4.0 ± 0.1) mm; brass nut to connect the top of the filter body to the bottom of the pipette to ensure a tight connection. An example of a correct connection is shown in Fig. ; filter mesh with a diameter of 15 mm, made of bronze or stainless steel wire, with a nominal opening size of 45 microns. The nominal wire diameter should be 32 µm, and the dimensional error of individual cells should be as follows: Each cell should not exceed the nominal size by more than 22 microns. The average cell size should not exceed the nominal size by ±3.1 µm. No more than 6% of cells can exceed the nominal size by more than 13 microns; brass mandrel (Fig.), in which the filtration mesh (item) is clamped with a reinforcing ring squeezed into the holder. The diameter of the working part of the mesh should be (12) mm; brass cylinder with external thread, which can be screwed into the housing hole (item) to press the mesh mandrel (item) through the gasket (item). At the bottom there should be four grooves that allow the sample to flow into the filtration apparatus. 6.8. Thermometers with measurement limits from minus 30 to plus 50 °C - to determine the maximum filterability temperature up to minus 30 ° C, from minus 80 to plus 20 °C - to determine the maximum filterability temperature below minus 30 °C, a thermometer for a cooling bath with temperature measurement limits from minus 80 to plus 20 °C. Use thermometers that meet the requirements given in the appendix. Note. Thermometers suitable for testing IP I C and 2C or ASTM 5C and 6C. 6.9. A cooling bath of any type, having a shape and dimensions suitable for placing a casing (item) in it in a stable vertical position to the required depth. The bathhouse must be equipped with a lid with holes to strengthen the support ring with the casing and the thermometer (item). The casing can be firmly attached to the lid. The temperature of the cooling bath must be maintained at the required level using a refrigerator or using an appropriate cooling mixture (section). For different filterability limit temperatures, it is necessary to maintain the cooling bath temperatures given in the table. They are achieved either by using separate cooling baths or by adjusting the refrigerator. Using a refrigerator makes it possible to quickly change the temperature of the bath. If several samples to be analyzed are placed in one large cooling bath, the distance between them must be at least 50 mm. 6.10. Glass stopcock, three-way, inclined, hole diameter 3 mm. 6.11. A vacuum pump or water pump with a power sufficient to provide a flow rate of 3 to 4 dm 3 / h in the vacuum regulator (item. ) during testing. 6.12. Vacuum regulator ( 17 ) (crap. ) - a glass bottle with a height of 350 - 400 mm, a capacity of 5 dm 3, filled to 3 / 4 water, sealed with a stopper with three holes for glass tubes. The two tubes should be short and should not be submerged in water. The third tube, with an internal diameter of approximately (6 ± 1) mm, should be long enough so that one end is immersed 200 mm in water and the other protrudes above the stopper. The depth of the immersed part must be set in such a way as to obtain a pressure drop across the pressure gauge containing water of exactly 200 mm water column. The installation is shown in Fig. . Full set of equipment 1 - cooling bath; 2 - insulating ring; 3 - pad; 4 - filter; 5 - measuring vessel; 6 - pad; 7 - casing; 8 - support ring; 9 - cork; 10 - pipette; 11 - calibration mark (20 cm 3); 12 - three-way stopcock; 13 - U -shaped pressure gauge; 14 - water; 15 - connection with the atmosphere; 16 - connection to a vacuum pump; 17 - glass bottle (buffer container); 18 - water level Crap. 1 6.13. Stopwatch with an error of 0.2 6.14. Semi-automatic device for determining the maximum filterability temperature of diesel fuels PAF according to TU 38.44710263-90, as well as other devices that provide the required testing accuracy. 6.15. Measuring vessels of the required dimensions can be selected from vessels that meet the requirements of the method according to GOST 20287. 6.16. Filter mesh made of stainless steel or copper alloy made of wire with a diameter of 0.028 to 0.032 mm and a number of cells from 17,000 to 20,500 per 1 cm 2 or No. 0045 N according to GOST 6613. 6.17. A cooling mixture consisting of solid carbon dioxide in accordance with GOST 12162 or solid carbon dioxide obtained by throttling liquid carbon dioxide into a dense bag and rectified ethyl alcohol in accordance with GOST 18300 or raw alcohol in accordance with GOST 131, or regenerated alcohol. 6.18. Thermometers type TINZ-1, TINZ-3, TN-8, GOST 400-80. 6.19. Mechanical stopwatch. Brass casing 1 - silver solder Crap. 2 Insulating ring and gaskets 1 - insulating ring; 2 - gaskets; 3a- stainless steel wires with a diameter of 2 mm Crap. 3 Support ring Crap. 4 Cork 1 - a slot that allows you to measure temperatures down to minus 30 °C; 2 - connection with the atmosphere; 3 - stainless steel clamp for securing the thermometer Crap. 5 Pipette 1 - calibration mark Crap. 6 Filter and- thread designation according to GOST 9150-81 1 / - knurling; 2 - pipette tube; 3 - brass nut; 4 - gasket made of oil-resistant plastic, ring, diameter 5.28×1.78; 5 - brass body; 6 - gasket made of oil-resistant plastic, ring-shaped, diameter 12.42×1.78; 7 - filter mesh mandrel; 8 - brass cylinder with external thread Crap. 7 Mandrel filter mesh 1 - mandrel body; 2 - reinforcing ring; 3 - filtration mesh Crap. 8 7. SAMPLE PREPARATIONA sample of the test fuel is filtered through dry filter paper (p.) at a temperature of at least 15 °C. A fuel sample is taken according to TOST 2517. To remove mechanical impurities and water, the fuel is filtered through a “white tape” filter at a temperature no less than 15 °C above the cloud point. 8. PREPARATION OF EQUIPMENTBefore each test, disassemble the filter (item) and wash its parts, as well as the measuring vessel (item), pipette (item) and thermometer (item) with a solvent, then rinse with acetone and dry with clean dry air. Check the cleanliness and dryness of all parts and casing. Check that the filtration mesh and connections are not damaged, and if necessary, replace them with new ones. Then the equipment is assembled as indicated in the devil. . Check the tightness of the threaded nut (p.) to see if there is a leak. 9. CONDUCT OF THE TEST9.1. The insulating ring (item) is placed on the bottom of the casing (item). 9.2. If the gaskets (item) are not made as one piece with the insulating ring (item), they are placed at a distance of about 15 and 75 mm from the bottom of the measuring vessel (item). 9.3. The measuring vessel is filled with the test fuel to the mark corresponding to 45 cm 3 . 9.4. The measuring vessel is closed with a stopper containing a pipette with a filter (item) and a corresponding thermometer (item). When the expected filterability limit temperature is below minus 30 °C, a thermometer with lower temperature limits is used. The thermometer must not be changed during the test. The equipment is installed in such a way that the lower part of the filter (item) is at the bottom of the measuring vessel; The thermometer is installed parallel to the pipette and in such a way that its lower end is (1.5 ± 0.2) mm from the bottom of the measuring vessel. The thermometer ball should not come into contact with either the wall of the measuring vessel or the filter. 9.5. The casing is placed vertically at a depth of (85 ± 2) mm in a cooling bath in which the temperature is maintained at minus (34 ± 0.5) °C. 9.6. The measuring vessel is placed in the housing in a stable vertical position. 9.7. With the shut-off valve open (item), connect the pipette to the vacuum unit (item , ) using flexible hoses connected to the tap (Fig. ). Turn on the vacuum and set the air flow so that U The -shaped pressure gauge showed a pressure drop of 200 mm water column during the entire test. 9.8. The determination begins immediately after placing the measuring vessel in the housing. If the cloud point of the sample is known, it is allowed to begin the determination at a time when the sample is cooled to a temperature that is at least 5 °C higher than the cloud point. In the first stage of cooling, you should always use a bath with a temperature of minus (34 ± 0.5) °C. When the sample temperature reaches the appropriate value, install a shut-off valve (p.) so that the filter is connected to a vacuum, causing the fuel sample to be sucked through the filtration mesh into the pipette, and at the same time turn on the stopwatch. When the fuel reaches the mark on the pipette, stop the stopwatch and set the valve to the initial position so that the sample can flow into the measuring vessel. If the time for fuel to be drawn in to the mark exceeds 60 s, then the determination is stopped and repeated with fresh test material, starting from a higher temperature. 9.9. Operation (p. ) is repeated after each decrease in sample temperature by 1 °C until the temperature at which flow through the filter stops is reached, or the pipette is not filled to the mark within 60 s. Record the temperature at the start of the last filtration. 9.10. If after cooling according to paragraph. and or the sample fills the pipette to the mark in no longer than 60 s, but does not flow back into the measuring vessel after installing the stopcock (item. ) in the initial position, then it is necessary to record the temperature at which filtration begins. 9.11. If at a temperature of minus 20 °C the flow of fuel through the filter does not stop, further cooling is carried out in a cooling bath with a temperature of minus (51 ± 1) ° WITH or in a correspondingly switched refrigerator and repeat the operation (p. ) after each temperature decrease by 1 °C. By changing the bath, quickly transfer the measuring vessel to a new casing placed in the second cooling bath, or by adjusting the refrigerator, Transfer the kit as indicated in paragraph . 10. TEST PROTOCOLRecord the temperature at the beginning of the last filtration with an accuracy of 1 °C (pp. - ) as the limiting temperature of filterability on a cold filter and make reference to this standard. Processing the results. The arithmetic mean of the results of two consecutive determinations, rounded to the nearest whole number, is taken as the result of the determination. 11. ACCURACY OF THE METHODThe accuracy of the method was obtained by statistical study of interlaboratory test results and is indicated in paragraphs. - (see note). The discrepancy between successive test results obtained by the same operator on the same equipment under the same conditions on identical test material, when the test was performed correctly, exceeds the values indicated in Fig. , in one case out of twenty. Two determination results obtained by one person in one laboratory are considered reliable (at a confidence level of 95%), if the discrepancy between them does not exceed 1 ° WITH. The discrepancy between two independent results obtained by equal operators working in different laboratories on identical test material, when the test was performed correctly, exceeds the values presented in Fig. , in one case out of twenty. Note Accuracy data presented oncrap , received under the program, in which both automatic and manual methods were used. Two test results obtained in two different laboratories are considered reliable (at a confidence level of 95%) if the discrepancy between them does not exceed 2 °C. Error in determining the maximum filterability temperature on a cold filter Note. Below minus 35 °C the error is not established. Crap. 9 APPLICATIONREQUIREMENTS FOR THERMOMETERS FOR DETERMINING THE LIMITING FILTERABILITY TEMPERATURE
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