Method of determining the content of mechanical impurities in oil or petroleum products

Purpose: is to filter the tested products with pre-dissolution of slowly filtered products in gasoline or toluene, washing the precipitate on the filter with solvent, followed by drying and weighing.
Apparatus
Glass laboratory utensils and equipment according to GOST 25336:
Water jet pump or other type that provides a maximum residual pressure of not more than 1.33×103 PA (10 mm Hg).
Glasses high with a spout from heat-resistant glass with a capacity of 200, 400, 600, 1000 cm3 or flasks КН-2-500-34ТС, КН-2-500-50ТС, КН-2-750-34ТС, КН-2-1000-34ТС КН-2-1000-42ТС, КН-2-1000-50ТС.
Jar weighing cups 14 / 8,19 / 9, 24/10, 34/12.
Flasks 1-500, 1-1000.
Funnels laboratory В-56 80ХС, В-75 110ХС.
Desiccators 1-190; 1-250; 2-190; 2-250.
Flushing tank (flushing).
Glass rod 150 to 200 mm long with a melted end.
Materials and reagents
Nefras-C 50/170 according to GOST 8505 or nefras C2 or C3 according to the documents establishing requirements to nephras, or straight-run gasoline with a boiling point not lower than 80 ° C.
Ethyl alcohol rectified from food raw materials according to GOST 5962 or technical ethyl alcohol rectified according to GOST 18300.
Ethyl ethyl technical.
Toluene oil according to GOST 14710 or GOST 5789. 2 GOST 6370-2018
A mixture of ethyl alcohol and toluene 1: 4 (by volume).
A mixture of ethyl alcohol and ethyl ether 4: 1 (by volume).
Silver nitrate in accordance with GOST 1277, a solution of 0.1 mol / dm3.
Distilled water according to GOST 6709.
Thermometer TL-2 1-2 according to GOST 28498.
Filter paper according to GOST 12026.
Vacuum meter that registers the residual pressure of 1.33×103 PA (10 mm Hg).

The presence of mechanical impurities in oil is explained by the conditions of its occurrence and methods of production. Mechanical impurities consist of particles of sand, clay and other hard rocks, which, settling on the water surface, contribute to the formation of an oil emulsion.
Solid mechanical impurities (sand, etc.) in lubricating oils are very harmful because they scratch the friction surfaces and erase them.
When determining the mass fraction of mechanical impurities, the sample of oil (petroleum product) is well mixed by shaking for 5 min in a bottle filled with no more than 3/4 of its capacity. Paraffin and viscous oils are preheated to 40–80 ° C.
In the analysis of oils containing water, which complicates filtration, the oil sample is dehydrated by distillation, or filter the solution of the sample. If a sample of less than 50 g is taken to determine the content of mechanical impurities, the dehydrated sample is mixed by shaking and the required sample is taken from it.
The red tape ashless paper filter in an open lid weighing cup is dried for at least two hours in an oven at 105-110 ° C, after which the cup is closed with a lid, cooled in a desiccator for 30 minutes and weighed to the nearest 0, 0002
The drying and weighing operation is repeated until the difference between two consecutive weighings is not more than 0.0004 g. Re-drying of the filter is carried out for 30 minutes.
From the mixed sample of the tested oil (oil product) take to the nearest 0.5 g a sample weighing 100 g, dilute it in the same glass with heated gasoline or benzene in two or four times. Heating of gasoline and benzene to dissolve the sample of test oils is carried out in a water bath. Boiling of the solvent during heating is not allowed.
The hot solution of the sample is filtered through an ashless filter brought to constant weight, which is located in a glass funnel fixed in a tripod. The solution is poured on the filter on a glass rod, the funnel with the filter is filled with a solution of not more than 3/4 of the height of the filter.
The rest of the oil (oil product) on the glass is washed off the filter with pure gasoline (benzene). Residues of solid impurities adhering to the walls of the glass are removed with a glass rod and washed on the filter with hot gasoline (benzene).
If the tested oil contains water, which complicates filtration, the oil samples are allowed to settle for 10-20 minutes, after which the gasoline (benzene) solution is first filtered, draining it from the sludge; then the sludge is diluted with five to ten times the amount of alcohol-ether mixture and also filtered. The residue in the flask is washed on the filter with an alcohol-ether mixture and hot gasoline (benzene).
When determining the content of mechanical impurities in slowly filtered oil (oil), filtration of the sample solution is allowed, and washing the filter should be carried out under vacuum and use a funnel for hot filtration.
For vacuum filtration, a rubber filter funnel is connected to a vacuum filtration flask connected to a vacuum pump.
The ashless paper filter is moistened with solvent and placed in a funnel so that the filter fits snugly against the walls of the funnel. When filtering in a Buchner funnel, the curved edges of the filter paper should fit snugly against the vertical walls of the funnel.
The funnel is filled with the solution no more than 3/4 of the height of the filter, each new portion is added after the previous one was filtered. When filtering using a hot filter funnel, boiling of the filtered solution is not allowed. At the end of the filtration, the filter with the precipitate is washed with hot gasoline using a washer with a rubber bulb until no traces of oil remain on the filter and the solvent will not flow transparent and colorless.
After washing, the filter with the precipitate is transferred to a weighing cup in which the clean filter was dried, dried with the lid open for at least two hours in an oven at 105-110 ° C, then close the lid, cool in a desiccator for 30 minutes and weighed to the nearest 0.0002 g
The drying and weighing operation is repeated until the difference between two consecutive weighings is not more than 0.0004 g. Repeated drying of the filter is carried out for 30 minutes.

Video determination of the content of mechanical impurities in oil or petroleum products

The content of mechanical impurities X (%) is calculated by the formula

X = (m1-m2) 100 / m3

where m1 is the weight of the weighing cup with filter and mechanical impurities, g;
m2 is the weight of the weighing cup with a clean filter, g;
m3– portion of oil (oil product), g.
The content of mechanical impurities is calculated as the arithmetic mean of the results of two parallel determinations.
Differences between parallel definitions should not exceed the values ​​given in table.
The content of mechanical impurities up to 0.005% inclusive is estimated as their absence.

Table – Differences between parallel definitions

The content of mechanical impurities,% Permissible discrepancy,%
Up to 0.01
From 0.01 to 0.1
From 0.1 to 1.0
More than 1.0		 0,005
0,01
0,02
0,20