Testing of petroleum products

The impurity content and moisture content also need to be tested.

The standard measurements are five: moisture, acid value, mechanical impurities, viscosity, and flash point. Of course, if you want to include all components, there will be a ton of projects.

Oh, the impurity content mentioned upstairs generally refers to specific analysis items; these need to be taken into account, and that’s covered in the book \"Oil Analysis\".

4# chengjingbao For compressor oil, apart from viscosity, moisture is the most important factor

For compressor oil, there seem to be specifications regarding the color of the oil, its acid value, viscosity, and the content of non-melting substances in n-heptane; relevant standards can be consulted for this information.

Determination of moisture in petroleum products 1 Scope and method overview This method is applicable to the determination of the water content in petroleum products, expressed as a percentage. A certain amount of the sample is mixed with an anhydrous solvent, and distillation is used to determine its moisture content, which is expressed as a percentage. 2 Instruments: Moisture analyzer (Figure 1): includes a round-bottomed glass flask 1 with a capacity of 500 milliliters, a receiver 2 (Figure 2), and a straight-tube condenser 3 with a length of 250–300 millimeters. The connections between the various parts of the moisture meter can be made using ground glass joints or cork plugs (ground glass joints must be used for the arbitration test). The scale of the receiver is marked in ten equal divisions down to 0.3 milliliters ； There are seven equal divisions marked between 0.3 and 1.0 milliliters ； Between 1.0 and 10 milliliters, each division is 0.2 milliliters. 3 Materials 3.1 Solvent: Industrial solvent oil or the fractions of straight-run gasoline at temperatures above 80°C; the solvent must be dehydrated and filtered before use. 3.2 Unglazed porcelain tiles, pumice, or glass capillaries with one end sealed must be dried before use. 4 Test Procedure 4.1 Shake the sample, whose volume does not exceed 3/4 of the bottle’s capacity, for 5 minutes to ensure uniform mixing. Viscous or paraffin-containing petroleum products should be pre-heated to 40–50°C before being shaken. 4.2 Weigh 100 grams of the well-stirred sample into the pre-washed and dried round-bottom flask 1, with an accuracy of 0.1 grams. Use a measuring cylinder to take 100 milliliters of solvent and pour it into an Erlenmeyer flask. After carefully shaking the mixture in the round-bottom flask, add some unglazed porcelain pieces, pumice, or capillaries. 4.2.1 For samples with low viscosity, 100 milliliters can be measured using a measuring cylinder and poured into an Erlenmeyer flask; then, another 100 milliliters of solvent is measured using the same uncleaned measuring cylinder. The weight of the sample in the round-bottom flask is equal to the product of the sample’s density and 100. 4.2.2 When the moisture content of the sample exceeds 10%, its weight should be reduced appropriately, ensuring that no more than 10 milliliters of water are evaporated. 4.3 The washed and dried receiver 2 should be tightly mounted on the round-bottom flask 1 using its branch pipe, such that the beveled end of the branch pipe extends 15–20 millimeters into the round-bottom flask. Then, a straight-tube condenser 3 is connected to the receiver. The inner wall of the condenser tube should be dried with cotton in advance. During installation, the axis lines of the condenser tube and the receiver must align with each other, and the beveled end of the condenser tube should face the outlet of the receiver’s branch pipe. To prevent vapor from escaping, put collodion on the gaps in the plug. When the temperature of the water entering the condenser differs significantly from room temperature, the upper end of the condenser should be plugged with cotton to prevent water vapor from the air from entering the condenser and condensing there. Note: It is allowed to connect a drying tube at the upper end of the condenser to prevent water vapor from the air from entering the condenser and condensing there. 4.4 Heat the round-bottom flask using an electric stove, an alcohol lamp, or a gas lamp set on a low flame, and control the reflux rate so that 2–4 drops of liquid fall from the inclined mouth of the condenser per second. 4.5 Near the end of distillation, if there are water droplets on the inner wall of the condenser, the mixture in the round-bottom flask should be allowed to boil vigorously for a short period of time, so that the condensed solvent can be used to wash the water droplets into the receiver as much as possible. 4.6 Heating should be stopped when the volume of water collected in the receiver no longer increases and the upper layer of the solvent becomes completely transparent. The reflux time should not exceed 1 hour. After stopping the heating, if there are still water droplets on the inner wall of the condenser, the solvent specified in item 3.1 should be poured from the upper end of the condenser to flush the water droplets into the receiver. If solvent washing is still ineffective, use one end of a wire or thin glass rod with a rubber or plastic tip to scrape the water droplets on the inner wall of the condenser into the receiver. 4.7 After the round-bottom flask has cooled, disassemble the apparatus and measure the volume of water collected in the receiver. When the solvent in the receiver becomes cloudy and the amount of water collected at the bottom of the tube is less than 0.3 milliliters, the receiver is placed in hot water for 20–30 minutes to clarify the solvent; after that, the receiver is cooled to room temperature before measuring the volume of water collected at the bottom of the tube. 5 Calculation 5.1 The weight percentage of moisture in the sample, X, is calculated using Equation (1): Where: V —— the volume of water collected in the receiver, in milliliters ； G —— Weight of the sample, in grams. Note: The density of water at room temperature can be considered as 1, so the number of milliliters of water is used as the equivalent weight in grams. When the weight of the sample is 100+1 grams, the number of milliliters of water collected in the receiver can be used as the result for determining the moisture content by weight of the sample. 5.2 The volume percentage of moisture in the sample, Y, is calculated using Equation (2): Where: V —— the volume of water collected in the receiver, in milliliters ； P —— Density of the sample when injected into the flask, grams per milliliter ； G —— Weight of the sample, in grams. Note: When 100 milliliters of the sample is taken, the volume of water collected in the receiver can be used as the result for determining the volume percentage of moisture in the sample. 6 Precision: The difference in the volume of water collected between two measurements should not exceed one scale division of the receiver. 7 Report 7.1 The arithmetic mean of the two results obtained from two measurements is taken as the moisture content of the sample. 7.2 If the moisture content of the sample is less than 0.03%, it is considered trace. No water was present in the receiver after the instrument was disassembled, so it is considered that the sample is free of water. Method source: GB/T 260-1977 (1988) Method for determining moisture in petroleum products – Section 6: Petroleum products – Method for determining water-soluble acids and bases. 1. Method overview and scope of application: Water-soluble acids or bases in the sample are extracted using distilled water or an ethanol-water solution. Then, the color change of the extract is examined using methyl orange or phenolphthalein as indicators, or the pH value of the extract is measured with a pH meter, in order to determine whether water-soluble acids or bases are present. This method is suitable for determining water-soluble acids or water-soluble bases in liquid petroleum products, additives, greases, paraffins, ceroses, and wax-containing components. 2 Instruments 2.1 Separatory funnel: 250 or 500 mL. 2.2 Test tubes: with a diameter of 15–20 mm and a height of 140–150 mm, made of colorless glass. 2.3 Funnel: Ordinary glass funnel. 2.4 Measuring cylinders: 25, 50, and 100 mL. 2.5 Erlenmeyer flasks: 100 and 250 mL. 2.6 Ceramic evaporation dish. 2.7 Electric heating plate and water bath. 2.8 pH meter: Equipped with a glass-silver chloride electrode (or glass-galvanometer electrode), with an accuracy of pH ≤ 0.01. 3 Reagents and Materials 3.1 Reagents 3.1.1 Methyl orange: Prepare an aqueous solution of methyl orange at 0.02%. 3.1.2 Phenolphthalein: Prepare a 1% phenolphthalein ethanol solution. 3.1.3 95% ethanol: analytically pure. 3.2 Materials 3.2.1 Filter paper: Industrial filter paper. 3.2.2 Solvent oil: Complies with the specifications for solvent oils used in the rubber industry as outlined in SH 0004. 3.2.3 Distilled water: It meets the requirements for grade 3 water as specified in GB/T 6682 \"Specifications and Test Methods for Water Used in Analytical Laboratories\". 4 Preparation Work 4.1 Preparation of the sample: 4.1.1 Place the sample in a glass bottle, filling it no more than three-quarters of its capacity, and shake for 5 minutes. Viscous or paraffin samples should be pre-heated to 50–60°C before shaking. 4.1.2 When the sample is grease, use a spatula to scrape off the top layer (3–5 mm) of the sample. Then, take approximately equal amounts of the sample from at least three locations that are not near the walls of the container, place them in a porcelain evaporating dish, and mix them carefully using a glass rod. 4.2 95% ethanol must be tested to be neutral using methyl orange and phenolphthalein indicators, or with a pH meter, before it can be used. 5 Test Procedure 5.1 When testing liquid petroleum products, place 50 mL of the sample and 50 mL of distilled water in a separatory funnel, and heat it to 50–60°C. Light petroleum products, such as gasoline and solvent oils, are not heated. For petroleum products with a kinematic viscosity greater than 75 mm2/s at 50°C, they should first be mixed with 50 mL of gasoline at room temperature, and then 50 mL of distilled water heated to 50–60°C should be added. Gently shake the test solution in the separatory funnel for 5 minutes; emulsification is not allowed. The clarified lower water layer is drained, filtered through filter paper, and poured into a conical flask. 5.2 When testing greases, paraffins, ozocerites, and wax-containing components, take 50 g of the pre-melted sample, weighing it to an accuracy of 0.01 g. Place it in a porcelain evaporating dish or conical flask, then add 50 mL of distilled water and boil until it melts completely. After cooling to room temperature, carefully pour the lower water layer into a funnel lined with filter paper and filter it into a conical flask. For solidified products (such as paraffin and ceresin), the wax layer is pierced in advance with a glass rod. 5.3 When testing additive products, pour 10 mL of the sample and 40 mL of solvent oil into an Erlenmeyer flask, then add 50 mL of distilled water heated to 50–60°C. Shake the separatory funnel for 5 minutes; once it has clarified, separate the lower water layer and filter it into an Erlenmeyer flask through a funnel lined with filter paper. 5.4 If oil products are mixed with water, that is, if water is used to extract water-soluble acids or bases resulting in emulsification, then a 1:1 solution of 95% ethanol in water at 50–60°C is used instead of distilled water, and the subsequent steps are carried out in accordance with section 5.1 or 5.3. Note: When testing diesel fuel, alkali-washed lubricating oil, additive-containing lubricating oil, and crude residual petroleum products, and the water extract of the sample shows an alkaline reaction to phenolphthalein (possibly due to the hydrolysis of soaps), the tests can also be carried out according to the steps in this section. 5.5 The extracts obtained from the first three or four tests shall be tested for water-soluble acids or bases using a pH meter or an indicator. 5.5.1 Determination of water-soluble acids or bases using a pH meter: Add 30–50 mL of the extract to a beaker, submerge the electrode to a depth of 10–12 mm, and determine the pH value in accordance with the instructions for using the pH meter. Determine whether water-soluble acids or bases are present in the aqueous or ethanol-aqueous extract of the sample according to the table below. 5.5.2 Determination of water-soluble acids or bases using an indicator: Add 1–2 mL of the extract to each of two test tubes. In the first test tube, add 2 drops of methyl orange solution, and compare it with a third test tube that contains the same volume of distilled water and methyl orange solution. If the extract is rose-colored, it indicates the presence of water-soluble acids in the petroleum product being tested. Add 3 drops of phenolphthalein solution to the second test tube containing the extract. If the solution is rose-colored or red, it indicates the presence of a water-soluble base. When the extract does not show a rose or red color using methyl orange or phenolphthalein as indicators, it is considered to contain no water-soluble acids or bases. 5.5.3 When there are discrepancies in the evaluation of petroleum product quality, the arbitration test for water-soluble acids or bases shall be conducted in accordance with 5.5.1. 6 Precision 6.1 These precision requirements apply only to the acidimetry method. 6.2 The difference between the two results obtained by the same operator should not be greater than 0.05 pH. 7 Report: The arithmetic mean of the two repeated measurements of the H value is taken as the test result. Section 7 Lubricating Oils — Qualitative Test Method for Water 1 Subject Matter and Scope This method specifies the procedure for qualitatively testing for water in lubricating oils. This method is applicable to lubricating oils. 2 Method Summary The sample is heated to a specified temperature, and the presence of certain components in the sample is determined qualitatively by listening to the sound produced. 3 Instruments 3.1 Oil bath: a cylindrical container with a diameter of about 100 mm and a height of about 90 mm, equipped with a metal lid ； At the center of the lid, a metal strut connects it from the inside to a metal disk; this disk is 80 mm below the lid and about 10 mm above the bottom of the bath. The lid has holes that correspond to those in the disk, for installing a thermometer and test tubes. 3.2 Test tubes: diameter 10–15 mm, height 120–150 mm. 3.3 Thermometer: 0～200℃. 3.4 Gas lamps or other heating devices. 4 Preparation 4.1 Fill the oil bath with mineral oil having a flash point of not less than 240°C, up to a height of 80 mm. Then, the oil bath was placed on a tripod and heated to 175°C ± 5°C. 4.2 Pour the sample into a glass test tube at room temperature to a height of 80–90 mm ； This test tube should be carefully washed and dried in advance. Insert the dry thermometer into the cork, then use this cork to seal the test tube, ensuring that the mercury bulb of the thermometer is located in the center of the test tube and at a height of about 20–30 mm above the bottom of the test tube. 5 Test procedure: Insert the test tube containing the sample vertically into the hot oil bath, and observe the tube and the sample carefully for several minutes until the temperature of the sample reaches 150°C. If there is moisture in the sample, foam is formed, a popping sound can be heard, and the test tube may even vibrate; the oil layer above the surface of the bath becomes cloudy. 6 Judgment of the results 6.1 If a significant noise is heard at least twice, it is determined that moisture is present. 6.2 If any of the following occur during the first test, another test shall be conducted: 6.2.1 A significant noise and foam are produced ； 6.2.2 Unsignificant noise and foam generation ； 6.2.3 Only foam. 6.3 If a significant noise and foam are observed again during repeated tests, it is considered that moisture is present ； If, when the temperature in the test tube reaches 130°C, there is only a slight noise and foam, or only foam, it is considered that the sample contains no moisture. Method source: SH/T 0257-92 (2004) Qualitative test method for moisture in greases

You just need to use compressor oil; in addition to testing the flash point and kinematic viscosity, it’s also advisable to check for moisture (using the method described on floor 7 for a qualitative assessment). If the temperature in the area is particularly low, the pour point should be measured. It is not necessary to measure the acid value; however, it is advisable to conduct acid value and corrosion tests if possible. A full analysis is completely unnecessary.

The original poster can take a look at **Standard GB 12691-90 for air compressor oils. I have this standard, but I don’t have the permission to upload it; if you need it, please contact me and I can send it to you via email

I work in the development of lubricants. If your sourcing channels are reliable, we should trust their quality; the factory certification is a guarantee of that quality. His tests were conducted in accordance with **specified standards**. We are users; we only examine a few particularly useful parameters before using something. For compressors, viscosity and water content are very important. If the viscosity is not appropriate, lubrication will not occur, which can damage the machine or result in higher power consumption. If the moisture level is not appropriate, it can cause the lubricant to emulsify and deteriorate, thereby losing its lubricating function. After being used for a period of time, lubricating oil loses quality due to aging. At this point, we should examine changes in parameters such as acid value, viscosity, and mechanical impurities in order to determine whether the quality of the oil has deteriorated enough to prevent its continued use. It’s not the case that the more items analyzed, the better.