GB/T 384-1981 Determination of Calorific Value of Petroleum Products

AI-translated method card — human verification pending. This is not an official translation of the standard. Unclear source values remain unverified; check the original standard and product certificate before use.

Incomplete source card: Sections 10, 11, 12, 13, 14 are absent from the available source. Only available content is translated; source completion is pending.

Card type: Test method

1. Method number / full name / English name / replacement relationship

• Standard number: GB 384-81 (confirmed in 1988)
• Chinese name: Determination of Calorific Value of Petroleum Products
• English name: Petroleum products-Determination of heat of combustion
• Replacement relationship: replaces GB 384-64
• Publication/implementation: issued by the National Bureau of Standards 1981-02-13, implemented on 1981-07-01
• Method composition: includes 1 bomb calorific value determination method, 2 gross calorific value determination method, 3 net calorific value determination method

2. Scope of application and non-applicability

• Applicable to the determination of the gross calorific value and net calorific value of water-free petroleum products (gasoline, jet fuel, diesel and heavy oil, etc.) using a calorimeter oxygen bomb.
• Not applicable: no explicit non-applicable clauses are provided in the available source.

3. Method principle

• Bomb calorific value determination method (1.1): Place the sample in a small dish inside the oxygen bomb, seal it with a flammable and airtight film, or seal the sample in an ampoule made of polyethylene tubing, burn the sample in compressed oxygen, and determine the calorific value generated during combustion (bomb calorific value), which serves as the basis for determining the gross calorific value and net calorific value.
• Gross calorific value determination method (2.1): First determine the sulfur content from the oxygen bomb washings (sulfur in the oxygen bomb is converted from sulfur dioxide to sulfuric acid, the sulfate ions are precipitated as barium sulfate, and the sulfur content is calculated from the barium sulfate weight); then introduce corrections into the bomb calorific value of the sample (the heat from the conversion of sulfur dioxide to sulfuric acid and the dissolution of sulfuric acid in water, and the heat from the formation of nitric acid from nitrogen and its dissolution in water) to obtain the gross calorific value.
• Net calorific value determination method (3.1): Determine the hydrogen content in the sample by experimental method or by formula calculation (the experimental method for determining hydrogen content is used only in particularly accurate analytical determinations); introduce a correction for the heat of formation of water vapor into the gross calorific value to obtain the net calorific value. Place pumice soaked with sulfuric acid of known weight as a water absorbent in the compressed oxygen in the oxygen bomb, and at the same time burn the weighed sample in a small dish sealed with film, but do not calculate the calorific value; place the oxygen bomb in boiling water and in air to absorb moisture; then determine the amount of water absorbed by the pumice.

4. Reagents and materials (purity / preparation)

• 1.3.1 Acetone: chemically pure, used as film solvent.
• 1.3.2 (the original number is suspected to be 3.4, requires confirmation against the source standard (source-text extraction)) Secondary standard calorimetric benzoic acid, for calorific value use only, must be certified by a factory commissioned by the National Institute of Metrology of China, and accompanied by a certificate (standard isooctane provided by the National Institute of Metrology of China may also be used).
• 1.3.3 Sodium hydroxide: chemically pure, prepared as 0.1N solution.
• 1.3.4 Phenolphthalein: prepared as 1% ethanol solution.
• 1.2.2.1 Polyethylene plastic tubing with inner diameter of 4 mm (for preparing ampoule sealed samples).
• 1.2.2.2 Ignition wire: nickel-chromium alloy, copper wire or other ignition wire with diameter not greater than 0.2 mm, cut into equal segments of length 60–120 mm (depending on the internal structure of the oxygen bomb and the ignition wire system), weigh a bundle consisting of 10–15 wires to determine the weight of each metal wire.
• 1.2.2.3 Bottled compressed oxygen: it should not contain hydrogen or other flammable impurities; electrolytic oxygen must not be used.
• 2.3.1 Hydrochloric acid: analytically pure.
• 2.3.2 Barium chloride: analytically pure, prepared as 10% aqueous solution.
• 2.3.3 Silver nitrate: analytically pure, prepared as 3% aqueous solution.
• 2.3.4 Methyl orange: prepared as 0.02% aqueous solution.
• 3.3.1 Pumice: porous.
• 3.3.2 Sulfuric acid: analytically pure.
• Table 1 Heat of combustion of ignition wire (cal/g): iron wire 1600; copper-nickel-manganese alloy wire 775; nickel-copper alloy wire 750; copper wire 800; chromium wire 335; platinum wire 100. Note: the diameter of each alloy wire is not greater than 0.2 mm.

5. Instruments and equipment

• 1.2.1.1 The calorimeter equipment and accessories for determining calorific value shall meet the various requirements for calorific value determination.
• 1.2.1.2 Calorimeter small dish (hereinafter referred to as small dish) Figure 1, made of stainless steel (dimension annotations source-text extraction severely noisy, requires confirmation against the source standard (source-text extraction)).
• 1.2.1.3 Flat dish made of porcelain or glass (a shallow crystallizing dish or watch glass with flat bottom and diameter of 100~200 mm may be used), for preparing film.
• 1.2.1.4 Metal tongs.
• 1.2.1.5 Pipette: 1 mL.
• 1.2.1.6 Stopwatch.
• 1.2.1.7 Syringe.
• 1.2.1.8 Analytical balance and heavy-duty 5 kg balance.
• 1.2.1.9 Volumetric flask: 2000 mL and 1000 mL.
• 2.2.1 Desiccator.
• 2.2.2 Porcelain crucible: low form.
• 2.2.3 Water bath.
• 2.2.4 Electric furnace.
• 2.2.5 Beaker: 300~500 mL.
• 2.2.6 Glass funnel: 60° angle, diameter 50~65 mm.
• 2.2.7 Wash bottle: 500~1000 mL.
• 2.2.8 Quantitative filter paper: slow speed, diameter 70~90 mm.
• 3.2.1 The instruments specified in 1.2.1 for the bomb calorific value determination method.
• 3.2.2 Porcelain spatula.
• 3.2.3 Porcelain crucible: low form, size 3 or 4 (depending on the size of the bottom of the calorimetric bomb), for holding water absorbent (with a specially made glass tripod).
• 3.2.4 Evaporating dish: size 4 or 5.
• 3.2.5 Weighing bottle: low form, diameter 35–50 mm (depending on the size of the porcelain crucible holding the water absorbent), tall form, diameter 30–40 mm, height 45~60 mm, for storing newly prepared pumice.
• 3.2.6 Metal can with lid: diameter 150–160 mm, height 200–220 mm, for holding hot water.
• 3.2.7 Electric furnace.
• 3.2.8 Desiccator.

6. Recommended operating conditions

• 1.2.3.1 The calorific value determination should be carried out in a separate room, with the room facing away from the sun, having double tightly sealed doors and windows, ensuring stable indoor temperature (temperature fluctuation should not exceed 5℃). There should be no heating devices in the room that affect the combustion heat determination. Ventilation is prohibited in the laboratory during the test.
• 1.2.3.2 The speed of the calorimeter stirrer should ensure rapid stirring of the water in the container without splashing; the temperature rise caused by stirring shall not exceed 0.01℃ per 10 minute. Stirrer revolutions per minute: vertical stirring should not be less than 50 revolutions, propeller type should not be less than 400 revolutions.
• 1.2.3.3 A general calorimetric thermometer or Beckmann thermometer (graduated in 0.01 degrees) should be used. This thermometer needs to be checked every 1 degrees by the national metrology authority, and its correction error should not be greater than 0.005℃.
• 1.2.3.4 (original number 1.2.2.4, requires confirmation against the source standard (source-text extraction)) When reading the temperature indication, a short-focus sight glass or binocular magnifier or double magnifier with magnification of 6–9 times and focal length of 0.5–1.0 meters should be used. This lens should be fixed on a specially made support and can move freely on a vertical support column without changing its strictly horizontal position. The magnifier must not be fixed on the thermometer.
• 1.2.3.5 An opening should be left on the ring of the oxygen bomb electrode to fix the calorimeter small dish on the ring.
• 1.2.3.6 Use a voltage lower than 12 volts for ignition. To avoid excess heat from the ignition wire heating, the energization time when burning the film and sample should not exceed 1 seconds. It is best to connect an indicator light in series in the circuit to observe the ignition situation. When the voltage in the circuit fluctuates greatly, it is best to use direct current for the power supply on the calorimeter.
• 1.2.3.7 The partial pressure indication range of the oxygen pressure gauge with pressure reducing valve is 0–60 or 0–75 kgf/cm², used for measuring the pressure in the bomb when the bomb is filled with oxygen. The oxygen bomb, pressure gauge and oxygen connecting pipe (using seamless copper pipe with diameter 1~1.5 mm) shall be subjected to hydrostatic pressure inspection as needed, and not less than once a year. The oxygen bomb should be tested at a pressure of 100 kgf/cm².
• 1.2.3.8 The connecting parts of compressed oxygen equipment are strictly prohibited from being coated with lubricating grease. If the oxygen bomb and oxygen connecting instruments are contaminated with lubricating oil or other oils during testing or transportation and show oil stains, they should first be carefully washed with gasoline, and then washed with ethanol or ether.
• 1.2.3.9 When operating with compressed oxygen, the operating procedures must be followed.
• 3.4.1 The oxygen bomb used for determining hydrogen content should be checked for airtightness and should not leak. Dry the oxygen bomb before use: open the exhaust valve several turns, blow with oxygen, and load the water absorbent (pumice soaked with sulfuric acid). Open the exhaust valve and screw the cover halfway in, and leave it in this state for at least 1 hours. At the same time, care must be taken to ensure that the end of the conductive pin and the end of the oxygen bomb oxygen pipe are not less than 20 mm from the edge of the porcelain crucible containing the water absorbent. Note: It is best to use a separate oxygen bomb for determining hydrogen content. In this case, the oxygen bomb is loaded with water absorbent when not in use. Only when water absorption is incomplete should the water absorbent be replaced.
• 3.4.2 The weighing bottle containing the porcelain crucible with water absorbent and the weighing bottle containing pumice soaked with sulfuric acid must be stored in a desiccator.
• 3.4.3 The porcelain crucible containing the water absorbent should be stored in a desiccator, and after use should be washed with water and dried.

7. Sampling and sample preparation

• 1.5.1 Preparation of film used for small dish:
  • 1.5.1.1 The film used for the small dish is prepared from 5–8% cellulose acetate movie film (cellulose nitrate movie film does not dissolve in acetone) or photographic film or acetone solution of cellulose acetate. This solution is prepared by soaking the movie film or photographic film in hot water, removing the emulsion, and drying, then weighing out the required amount of film, cutting it into small pieces, transferring to a glass bottle or conical flask, and pouring in an appropriate amount of acetone. If cellulose acetate is used, directly weigh an appropriate amount into a conical flask, pour in an appropriate amount of acetone, stopper the flask, and shake until the film is completely dissolved. Note: ① 200 mL of 5–8% movie film or photographic film solution is sufficient for making film for 150~200 calorific value determinations (including the determination of the calorific value of the film itself, and the solution used for preparing the film and adhering the film to the small dish). ② A collodion solution dissolved in ether may be used instead of the movie film or photographic film solution dissolved in acetone.
  • 1.5.1.2 Measure 4–5 milliliters of the prepared solution and pour it onto a crystallization dish or flat plate with a diameter of 100 millimeters. Then tilt the container in all directions so that the solution in it forms a uniform thin layer. After 10–15 minutes, when the surface of the formed film is no longer glossy, pour in an appropriate amount of hot water to cover it. When the film begins to wrinkle from its edges and detach, remove the film from the surface of the dish and press it between filter papers. Leave the prepared film between filter papers to dry for one day and one night. The prepared film must be stored in a metal box or paper box.
• 1.5.2 Preparation of polyethylene plastic ampoule: take a section of polyethylene plastic tube and soften it over the flame of an alcohol lamp, draw one end slightly thinner, then melt and seal the thin end (as shown in Figure 2). After sealing, soften it over the alcohol lamp (do not let the plastic tube directly contact the flame), then remove it from the flame, and blow through a drying tube containing calcium chloride with the mouth (to avoid blowing in water vapor) to form a plastic ampoule sealed-sample tube with a capillary (as shown in Figure 3). The weight of the sealed-sample tube is about 0.2 grams. After blowing, place it in a desiccator for later use.
• 1.5.3 Determination of the bomb calorific value of film or polyethylene plastic ampoule:
  • 1.5.3.1 The determination of the bomb calorific value of film or polyethylene plastic ampoule is used as a correction value when calculating the calorific value of the sample.
  • 1.5.3.2 When determining the calorific value, the film is rolled into about 0.5–0.7 grams, and the polyethylene plastic ampoule is taken in 0.5–0.6 grams. Weigh accurately to 0.0002 grams. Tie the film or polyethylene plastic ampoule to the ignition wire (cotton thread may also be used to tie it to help combustion), and place it in a small dish.
  • 1.5.3.3 According to 1.4.2 and 1.4.3 of this method, carry out the preparation work of the calorimeter, and make the temperature of the water injected into the calorimeter lower than that of the outer shell by 0.5~1.0℃.
  • 1.5.3.4 Then according to 1.4.5~1.4.8 of this method, carry out the test (the difference being that film or polyethylene plastic ampoule is used instead of benzoic acid). After the test, do not collect the washing liquid of the oxygen bomb.
  • 1.5.3.5 The bomb calorific value Q_D/1 (cal/g) of the film or polyethylene plastic ampoule is calculated according to formula (3) (formula source-text extraction has severe noise, requires confirmation against the source standard (source-text extraction)).
  • 1.5.3.6 The bomb calorific value of the film or polyethylene plastic ampoule shall be the arithmetic mean of no fewer than two test results, and the difference between the test results shall not exceed 40 cal/g.
• 1.5.4 Preparation of the small dish:
  • 1.5.4.1 Before determination, ignite the small dish at 750±5℃ for 10 minutes, and after cooling, weigh accurately to 0.0002 grams.
  • 1.5.4.2 From the film prepared according to 1.5.1 of this method, cut one small strip for ignition with a width of 6–8 millimeters and a length of 30–35 millimeters, and one circular piece with a diameter slightly larger than the outer edge of the small dish.
  • 1.5.4.3 Use a glass rod to drip 1 drops of the acetone solution of the film onto the wall of the small dish opposite the small hole on the side, fix one end of the ignition strip on the inner wall of the small dish, and fold the other end outside the small dish. Then use the solution to coat the place on the edge of the small dish where the ignition strip is fixed, fold over the part of the ignition strip that is not adhered, then use the solution to coat the entire edge of the small dish, and place the prepared circular film on it and adhere it well, making sure it fits tightly with the edge of the small dish. After cutting off the protruding edge of the film, carefully coat the edge of the small dish with the solution (forming a uniform thin layer), so that the joint between the film and the edge of the small dish can achieve a very tight fit. After the film is adhered, place the small dish in air to dry for 1~2 hours, while keeping the side hole of the small dish open.
  • 1.5.4.4 After 1~2 hours, close the side hole of the small dish with a stopper, prick a hole in the protruding end of the ignition strip, weigh the small dish accurately to 0.0002 grams, and calculate the weight of the adhered film. Note: ① First examine the film against light for holes, and use only the good-quality part to cover the small dish. ② For the determination of the calorific value of heavy petroleum products, do not carry out the operations of 1.5.1, 1.5.2, 1.5.3 in the preparation work and 1.5.4 in 1.5.4.2, 1.5.4.3, 1.5.4.4.
• 1.6.2 Film sealing of sample: when testing kerosene, if film sealing is used, use a syringe to inject 0.5–0.6 grams of sample through the side hole into the small dish prepared according to 1.5.4 of this method, and carefully close the hole with a stopper. When testing heavy petroleum products, add 0.6–0.8 grams of sample to the small dish prepared according to 1.5.4.1 of this method (for waxy viscous heavy oil products, preheat to 40~50℃, mix, and then sample). Thereafter, weigh the small dish and sample accurately to 0.0002 grams, and calculate the weight of the sample.
• 1.6.4 (original number 1.8.4, requires confirmation against the source standard (source-text extraction)) Polyethylene plastic ampoule sealing of sample: when testing volatile samples, use polyethylene plastic ampoule sealing. Weigh the ampoule (as shown in Figure 3) in advance on an analytical balance, accurately to 0.0002 grams, then inject 0.5–0.6 grams of the pre-cooled sample into the plastic ampoule with a syringe, immediately pinch the middle of the capillary by hand, let the upper end of the capillary melt and seal above the flame of an alcohol lamp. After sealing, cool for a while, then place it on the analytical balance and weigh, accurately to 0.0002 grams. Tie the capillary end of the polyethylene plastic ampoule with the sealed sample to the ignition wire (it may also be tied together with the ignition wire using a cotton thread), place the bottom on the small dish, put it into the oxygen bomb, and fill with oxygen to 30–32 kilograms-force/centimeter² without allowing air to escape.
• 3.5.1 Preparation of absorbent:
  • 3.5.1.1 Break about 150–200 grams of pumice into fragments, and select (or sieve) fragments of 3–5 millimeters. Ignite the prepared fragments at high temperature of 800℃ for 1.5~2 hours, place the cooled pumice in a porcelain dish, pour in sulfuric acid to form a thick paste-like substance, and transfer to an electric furnace.
  • 3.5.1.2 Heat the pumice with sulfuric acid to boiling, while occasionally stirring the mixture with a glass rod. After boiling for 30 minutes, allow the porcelain dish containing the pumice to cool slightly, and check whether acid absorption is sufficient. If the acid has been completely absorbed, then add 10~15 milliliters of sulfuric acid, and boil for another half hour. Carefully pour off the excess portion, then boil the mixture again. After boiling for 1 hours, remove the porcelain dish from the electric furnace and let it cool until the sulfuric acid stops evaporating. Then transfer the warm pumice into several weighing bottles and store in a desiccator. The pumice thus prepared must appear dry in appearance. Note: Used pumice is also regenerated by this method, and a small amount of sulfuric acid must be added during treatment.
• 3.5.3.3 When testing light petroleum products, use a syringe to inject the sample through the side hole into the small dish prepared according to 1.5.4 of the bomb calorific value determination method, and carefully close the hole with a stopper. When testing heavy petroleum products, add 0.3~0.4 grams of sample to the small dish prepared according to 1.5.4.1 of the bomb calorific value determination method (for petroleum products with higher hydrogen content, reduce the amount as appropriate), and weigh it accurately to 0.0002 grams.

8. Analysis procedure

• 1.4 Determination of the water value of the calorimeter:
  • 1.4.1 The water value of the calorimeter is determined by burning a certain amount of standard benzoic acid or standard isooctane in an oxygen bomb and measuring the temperature change of the calorimeter caused by the heat generated by its combustion. The heat (calories) required to raise the calorimeter temperature by 1℃, i.e., the water value, is expressed in cal/℃. The calorimeter consists of the calorimetric container and the water in it, the oxygen bomb, the stirrer, and the thermometer, etc. (in the immersed state).
  • 1.4.2 Before carrying out the determination, the container must be wiped dry, then distilled water is poured into the calorimeter, weighed accurately to ±0.5 grams. If the measurement is always carried out within the same temperature range (temperature variation within 5℃), the water may also be measured with a volumetric flask. The amount of water charged shall be such that the oxygen bomb is immersed in water up to 2/3 of the lock nut of the intake valve. In subsequent tests of samples, the same amount of water shall be used.
  • 1.4.3 Before the calorimetric container is placed into the calorimeter outer shell, the water temperature in the calorimetric container shall be lower than the water temperature in the outer shell by 1~2.0℃. Place the container holding water on the insulating base in the calorimeter outer shell.
  • 1.4.4 Weigh 1±0.1 grams of compressed benzoic acid pellet in a pre-weighed small dish accurately to 0.0002 grams (before tabletting, standard benzoic acid shall be dried in a desiccator containing concentrated sulfuric acid or phosphorus pentoxide for more than 24 hours). The ignition wire is pressed into the benzoic acid pellet, leaving both ends exposed. If cotton thread is used for ignition, the ignition wire may also be omitted. Note: If standard isooctane is used to determine the water value of the calorimeter, a polyethylene plastic ampoule or glass ampoule may be used for sealing the sample.
  • 1.4.5 Use a pipette to accurately inject 1 milliliters of distilled water into the oxygen bomb, fix the small dish containing benzoic acid on the ring of the oxygen bomb electrode, pass the stopper through the opening of the ring, and connect the two ends of the ignition wire to the electrodes respectively, then tighten the oxygen bomb. Carefully fill the bomb with oxygen from the intake valve tube to a pressure of 30~32 kilograms-force/centimeter², without allowing air to escape from the oxygen bomb.
  • 1.4.6 (original number 1.4.8, requires confirmation against the source standard (source-text extraction)) Carefully sink the oxygen bomb into the calorimetric container holding water without losing water, connect the wires to the oxygen bomb electrodes, then insert the stirrer and thermometer into the water, cover the lid, and then start the stirrer. The thermometer and stirrer shall not touch the oxygen bomb or the wall of the calorimetric container. The center of the mercury bulb of the thermometer is located at 1/2 of the height of the oxygen bomb. The stirring part of the stirrer shall not be exposed above the water surface. Let the apparatus equilibrate for 5 minutes before starting the calorimetric test.
  • 1.4.7 The calorimetric test is divided into three periods:
    • "Initial period" — carried out before burning the sample. Under the temperature conditions at the beginning of the test, observe and calculate the heat exchange between the calorimeter and the surrounding environment;
    • "Main period" — during this time the sample begins to burn, and the heat of combustion is transferred to the calorimeter;
    • "Final period" — carried out immediately after the main period, its function is the same as the initial period, namely to observe and calculate the heat exchange under the temperature conditions at the end of the test.
    • After the apparatus temperature reaches equilibrium, record the initial temperature of the test, and begin initial-period temperature readings, reading once per minute for a total of 5 readings, accurate to 0.001℃. When reading the last initial-period temperature, switch on the current, then carry out main-period temperature readings, then final-period temperature readings, reading once every half minute, each reading accurate to 0.001℃.
    • In order to overcome the capillary hindering the uniform rise of the mercury convex surface, before each temperature reading, start the thermometer vibrator to vibrate or tap the thermometer lightly with a thin rod with a rubber tube on the end (except for readings during the "main period" when the temperature rises rapidly).
    • In the main period, when the water temperature in the calorimeter no longer rises and begins to remain constant or fall, the point before that is taken as the end point of the main period. The main period is generally about 14 half-minutes. Immediately following is the first reading of the final period; the final period has a total of 10 readings. Examples of records of bomb calorific value determination results are shown in Table 3 and Table 4.
  • 1.4.8 After the test is completed, turn off the motor, remove the thermometer, take the oxygen bomb out of the calorimeter, carefully and slowly open the exhaust valve, and release the gas in the bomb at a uniform rate; this operation shall take no less than 1 minutes. Then open and remove the cover of the oxygen bomb, and check whether combustion inside the oxygen bomb is complete. If unburned sample or oil smoke deposits are found, the test is discarded.
  • 1.4.9 Wash the inside of the oxygen bomb, the small dish, and the exhaust valve with distilled water, and collect all the washings in a conical flask; the water used for hand washing should be 150~200 milliliters.
  • 1.4.10 When calculating the water value determination result of the calorimeter, attention should be paid to the correction for the heat generated and dissolved by nitric acid in water. Titrate the washings of the oxygen bomb with 0.1N sodium hydroxide solution to determine the amount of nitric acid formed. For this purpose, cover the beaker containing the washings with a watch glass, heat to boiling and boil for 5 minutes. Then add 2 drops of phenolphthalein indicator, and titrate with 0.1N sodium hydroxide solution until a rose color that does not disappear appears.
  • 1.4.11 The water value of the calorimeter K (cal/℃) is calculated according to formula (1) (formula source-text extraction is severely noisy, requires confirmation against the source standard (source-text extraction)).
  • 1.4.12 The water value is the arithmetic mean of not less than 5 determination results (the error between the determination results should not exceed 10 cal/℃), and these experiments should be conducted within 3 days respectively.
  • 1.4.13 Regarding the determination of the water value, whenever the operating conditions of the calorimeter change each time (i.e., after partial replacement or repair of the calorific value determination apparatus, when replacing the thermometer, when the indoor temperature varies by more than ±5℃, and when the calorimeter is moved to another location), the determination must be carried out again. Under normal conditions, the determination should be carried out at least once every 3 months.
• 1.6 Test procedure:
  • 1.6.1 Carry out the preparation of the calorimeter according to 1.4.2 and 1.4.3 of this method.
  • 1.6.2 Film sample sealing (see Section 7).
  • 1.6.3 Fix the small dish containing the sample on the ring of the electrode, pass the stopper through the opening of the ring, fix one end of the fuse wire on the electrode; when testing light petroleum products, pass the other end of the fuse wire through the ignition strip and fix it to the other end of the electrode. When testing heavy oil products, immerse the middle section of the fuse wire in the sample in the small dish, so that the fuse wire forms a U shape (as shown in Figure 4), with both ends fixed to the electrodes respectively, carefully tighten the oxygen bomb, then slowly (to avoid rupture of the film) fill oxygen through the inlet valve tube to a pressure of 30~32 kgf/cm², without allowing air to escape.
  • 1.6.4 Polyethylene plastic ampoule sample sealing (see Section 7).
  • 1.6.5 (original number 1.8.5, requires confirmation against the source standard (source-text extraction)) The calorimetric test is carried out according to 1.4.6~1.4.10 of this method.
• 2.4 Gross calorific value test procedure:
  • 2.4.1 After burning the sample, filter the washings from the oxygen bomb obtained according to the bomb calorific value determination method 1.4.9, then add distilled water to reach 300–350 milliliters, add 2–3 drops of methyl orange indicator to the resulting filtrate, and add a small amount of hydrochloric acid, then heat to near boiling, and gradually add 10 milliliters of 10% barium chloride solution heated to boiling, and place the beaker containing the barium sulfate precipitate on a boiling water bath for 2 hours.
  • 2.4.2 After filtering the contents of the beaker with quantitative filter paper, wash the barium sulfate precipitate on the filter paper with hot water until chloride ions are completely removed (until a drop of 1 drops of filtrate in silver nitrate solution does not show turbidity).
  • 2.4.3 Transfer the filter paper with the precipitate to a porcelain crucible, press it slightly, then carefully preheat the crucible (on an electric furnace or alcohol lamp) to dry the filter paper first, then carbonize and ash it. But do not let the filter paper burn. Thereafter, calcine the crucible and its contents in a high-temperature furnace at 800~850℃ until the difference between two consecutive weighings is less than 0.001 grams.
  • 2.4.4 The sulfur content of the sample S (%) is calculated according to formula (5) (formula source-text extraction is severely noisy, requires confirmation against the source standard (source-text extraction)).
• 3.5 Net calorific value test procedure:
  • 3.5.2 Blank test:
    • 3.5.2.1 Place 7~8 grams of pumice soaked with sulfuric acid into a crucible, and weigh this pumice and crucible in a covered weighing bottle, accurate to 0.0002 grams. Then, quickly place the crucible on the glass tripod at the bottom of the oxygen bomb, and then tighten the oxygen bomb cover.
    • 3.5.2.2 Through the tube of the inlet valve, carefully (without blowing away the pumice) fill the oxygen bomb with oxygen to a pressure of 30~32 kgf/cm² (without allowing air to escape from the bomb), then leave it at room temperature for 1 hours.
    • 3.5.2.3 Within 4~5 minutes, carefully release the oxygen from the oxygen bomb, unscrew the cover, quickly transfer the crucible containing pumice from the oxygen bomb into a weighing bottle, and determine the amount of water increased in the pumice.
    • 3.5.2.4 The blank test should be carried out at least twice; if the test results show significant variation (more than 1~2 milligrams), supplementary determinations must be made. Finally, calculate the average correction for the moisture in the oxygen, the moisture in the air in the oxygen bomb volume, the moisture adsorbed on the inner surface of the oxygen bomb, and the moisture absorbed by the absorbent when moving back and forth between the weighing bottle and the oxygen bomb. Each time the oxygen cylinder is replaced, the moisture correction must be determined.
  • 3.5.3 Determination of hydrogen:
    • 3.5.3.1 Fill the calorimetric container with distilled water, no need for precise weighing, but the amount must be such that the oxygen bomb is submerged up to the lock nut of the valve, and the water temperature should be the same as room temperature. Place the container with water on the insulating base in the calorimeter jacket.
    • 3.5.3.2 In a porcelain crucible in a covered weighing bottle, weigh 7~8 grams of pumice soaked with sulfuric acid, accurate to 0.0002 grams; before placing into the oxygen bomb, place the weighing bottle containing the pumice in a desiccator.
    • 3.5.3.3 When testing light petroleum products, use a syringe to inject the sample through the side hole into the small dish prepared according to the bomb calorific value determination method 1.5.4, and carefully close the hole with a stopper. When testing heavy petroleum products, add 0.3~0.4 grams of sample to the small dish prepared according to the bomb calorific value determination method 1.5.4.1 (for petroleum products with higher hydrogen content, reduce the amount accordingly), and weigh it accurately to 0.0002 grams.
    • 3.5.3.4 Fix the small dish containing the sample on the ring of the electrode, while passing the stopper through the opening of the ring, then connect one end of the fuse wire to the electrode; when testing light petroleum products, pass the other end of the fuse wire through the ignition strip and fix it to the other end of the electrode. When testing heavy petroleum products, immerse the middle section of the fuse wire in the sample in the small dish, so that the fuse wire forms a U shape (as shown in Figure 4), with both ends fixed to the electrodes respectively.
    • 3.5.3.5 Transfer the crucible containing sulfuric acid-soaked pumice to the glass tripod at the bottom of the oxygen bomb, carefully tighten the cover by hand, and carefully (to avoid rupture of the film and blowing away of the pumice) fill the oxygen bomb with oxygen through the inlet valve tube to a pressure of 30~32 kgf/cm², without allowing air to escape from the oxygen bomb. Carefully immerse the oxygen bomb in the calorimetric container filled with water, and connect the wires to the oxygen bomb electrodes. Immerse the stirrer and thermometer in the water, cover the jacket with the lid, and then start the stirrer.
    • 3.5.3.6 Leave the entire apparatus under stirring for 2~3 minutes to allow the temperature to become uniform. Then turn on the ignition circuit, and observe whether the sample ignites according to the rise of the mercury column of the thermometer (or according to the indicator light).
    • 3.5.3.7 Take the oxygen bomb out of the calorimeter, pass the copper wire through the hole in the valve head, then transfer the oxygen bomb into a metal can prepared with boiling water, and place this metal can on an electric furnace. When filling the metal can with water, it should reach the mark so that the oxygen bomb is completely submerged when immersed. Leave the oxygen bomb in boiling water for 30 minutes, then take the oxygen bomb out of the water and leave it at room temperature for 1 hours; if the oxygen bomb has not completely cooled during this period, it can be immersed in cold water for 2~3 minutes until it reaches room temperature.
    • 3.5.3.8 Slowly release the gas from the oxygen bomb within 4~5 minutes, unscrew the cover, quickly transfer the crucible containing pumice from the bomb into a weighing bottle, and determine the amount of water increased in the pumice.
    • 3.5.3.9 Inspect the inner surface of the oxygen bomb to determine whether the sample has completely burned and whether the moisture has been completely absorbed. The inner surface of the oxygen bomb should be dry. However, in the case of burning petroleum products containing a large amount of sulfur, it may be slightly moist due to contact with air. If soot or unabsorbed moisture is present on the inner wall of the oxygen bomb, the test is invalid.
    • 3.5.3.10 Collect the used pumice in a wide-mouth bottle with a ground stopper for regeneration.

9. Qualitative and quantitative and calculation formulas

• 1.4.11 The water value of the calorimeter K (cal/℃) is calculated according to formula (1) (formula source-text extraction is severely noisy, requires confirmation against the source standard (source-text extraction)). Symbols in the formula: Q—— heat of combustion of standard benzoic acid or standard isooctane (see data provided by the trademark of the standard reagent used), cal/g; G—— weight of standard benzoic acid or standard isooctane, g; Q1—— heat of combustion of fuse wire (see Table 1), cal/g; G1—— weight of fuse wire, g; 1.43—— heat released per 1 milliliters of 0.1N sodium hydroxide solution neutralizing nitric acid, cal/mL; V—— volume of 0.1N sodium hydroxide solution consumed in titrating the oxygen bomb washings, mL; R——0.1N concentration correction number of sodium hydroxide solution; t_n—— final temperature of the main period, ℃; h—— correction number of the thermometer at temperature t_n, ℃; t_0—— initial temperature of the main period, ℃ (i.e., the temperature at ignition, also the final temperature of the initial period); h_0—— correction number of the thermometer at temperature t_0, ℃; Δt—— correction number for heat exchange between the calorimeter and the surrounding environment, calculated according to formula (2), ℃; H—— correction coefficient found from the calibration certificate of the Beckmann thermometer (when using a general calorimetric thermometer with constant mercury amount, H=1.000).
• The heat correction coefficient of the calorimeter and the surrounding environment Δt (℃) is calculated according to formula (2) (formula source-text extraction is severely noisy, requires confirmation against the source standard (source-text extraction)). In the formula: Δt1—— average temperature change per half minute in the initial period, ℃; Δt2—— average temperature change per half minute in the final period, ℃; m—— number of half-minute intervals during rapid temperature rise in the main period, its value determined according to the data in Table 2; n—— number of half-minute intervals during slower temperature rise in the main period, its value equal to the total number of half-minute intervals in the main period minus the value of m.
• Table 2 m values: standard value 0.50 and below → m=9; 0.51–0.64 → m=8; 0.65–0.73 → m=7; 0.74–0.82 → m=6; 0.83–0.91 → m=5; 0.92~0.95 → m=4; 0.95 and above → m=3. In the standard values: t_4—— the fourth temperature in the main period, ℃; t_0—— the temperature at the start of the main period (that is, the last temperature of the initial period), ℃;