4. Carbon Residue Test (Experiment No.3) 1 1. OBJECTIVES: 1) To be able to determine the carbon residue of a liquid fuel. 2) To be able to know the definition of a carbon residue test. 3) To be able to have knowledge about carbon residue of a liquid fuel. 2 2. THEORY AND HYPOTHESIS: Carbon residue for a fossil fuel can be defined as the tendency of that fuel to form carbon deposits at high temperature in an inert atmosphere. Carbon residue for a fuel is measured in weight percentage (wt %) or parts per million by weight (ppm wt). High carbon residue value is undesirable for a fuel. 3 4 . Under engine-operating conditions.) When oil is heated to a high temperature in the absence of sufficient air a portion of the oil will distill.2. thus leaving a carbon residue.. THEORY AND HYPOTHESIS: (cont. the amount and type of the carbon formed has an important effect upon the performance of the engine. The amount of this residue is an index to the extent the oil is likely to decompose in service. a relatively smaller amount in one oil compared with another should be favorable.) While no maximum residue specifications for lubricating oils are commonly given..2. THEORY AND HYPOTHESIS: (cont. 5 . . It consist of a porcelain crucible with a Skidmore iron crucible resting upon a layer of sand in a second larger iron crucible. 6 .2.) Apparatus known as the Conradson carbonresidue tester is widely used in this country. THEORY AND HYPOTHESIS: (cont. all of which are supported upon a wire triangle on a metal stand of specified dimensions. Heat is applied by a Meker burner. An analytical balance is used to weigh the sample of oil and the residue.. 7 .) The assembled tester is shown in the figure. The crucibles are surrounded by an asbestos block and covered by a sheet-iron hood and chimney.2. THEORY AND HYPOTHESIS: (cont. THEORY AND HYPOTHESIS: (cont..2.) 8 . ) A clean porcelain crucible is weighed to the nearest 5mg. The crucible is then placed in a Skidmore crucible. then filled with a 10g sample of oil and weighed to the same accuracy. THEORY AND HYPOTHESIS: (cont. and the assembly of crucibles is centered on a wire triangle with the asbestos insulation on a suitable ring stand. 9 .. The sand in the large iron crucible is leveled.2. and the Skidmore crucibles are covered. . 10 . THEORY AND HYPOTHESIS: (cont. the burner is moved or tilted so that the flame passes up one side of the crucible and ignites the oil vapor. When smoke appears from the chimney. and heat is applied with a strong flame from the Meker burner so that the pre ignition period will be from 8.) The whole is covered with the sheet-iron hood.2.5 min.5 to 11. ) The burner is momentarily removed and the gas flame adjusted so that the vapors burn uniformly with the high flame above the chimney but not above the bridge on top of the chimney. The burning period should be from 12 to 14 min. THEORY AND HYPOTHESIS: (cont.2.. 11 . The burner is then removed and the apparatus is allowed to cool for about 15 min..) When the burning and smoking have ceased.2. the burner is adjusted so that the bottom of the iron crucible is heated to a cherry red for exactly 7 min. The total period of heating should be 28 to 32 min. 12 . THEORY AND HYPOTHESIS: (cont. .) The porcelain crucible and contents are reweighed.2. and the percentage of carbon residue is calculated on the basis of the original sample weight. THEORY AND HYPOTHESIS: (cont. 13 . . Also through the experiment it was found out that Carison residue is very small compared to the amount of other components in oil. THEORY AND HYPOTHESIS: (cont. Carbon residue test determine the percentage of carbon that remains in a sample after the volatile vapors had been driven off by heat. 14 .) The Conradson Test for the amount of carbon in oil is accurate if test is properly performed.2. 3. LIST OF APPARATUS: 1) Meker Bunsen Burner 15 . ) 2) Hood Porcelain Crucible 16 .. LIST OF APPARATUS: (cont.3. . LIST OF APPARATUS: (cont.) 3) Tripod 17 .3. 3.) 4) Wire Mesh 18 . LIST OF APPARATUS: (cont.. ) 5) Chimney 19 .3. LIST OF APPARATUS: (cont.. 4. SET – UP OF APPARATUS: 20 . 21 . PROCEDURES: 1) Place the two glass bends provided which are about 1” in diameter in the porcelain crucible and include their weight in the net weight of the crucible. add 10 grams of the oil to be tested accurately weighed and free from impurities. Then.5. 5.. 22 . PROCEDURES: (cont. Level the sand in the sheetiron crucible and set the Skidmore crucible as it is in the exact center of the iron crucible.) 2) Place the crucible in the center of the Skidmore crucible. the one to the later fitting loosely to allow exit of vapors that are formed. PROCEDURES: (cont.5.) 3) Apply the covers to both the Skidmore and the iron crucible.. 23 . Center the short iron crucible into the block with its bottom resting on top of the triangle and cover the whole with the sheet iron hood in order to distribute the heat during the process. PROCEDURES: (cont..5. 24 .) 4) Place the bare nichrome wire triangle on the metal tripod on the asbestos block as hollow sheet metal box. PROCEDURES: (cont..5.) 5) Apply heat with a highly strong flame from a Meker type gas burner so that the pre ignition period will be 10 and 1 1/2 minutes. immediately move or tilt the burner so that the gas flame plays on the sides of the crucible for the purpose of igniting the vapors. 25 . When some smoke appear above the chimney. 26 . remove the heat temporarily and before replacing adjust the gas flame so that the ignited vapors burn uniformly with the flame above the chimney. The period of burning the vapors shall be 13 and 1 minutes. PROCEDURES: (cont. when the flame does not show above the chimney.. but not above the wire bridge.) Then.5. Heat may be increased if necessary. 27 . The total period of heating should be 2 to 30 minutes.) 6) When the vapors cease to burn and no further blue smoke can be seen. PROCEDURES: (cont. and the cover part of the sheet-iron crucible. red and maintain for exactly 7 minutes. readjust the burner to hold the heat as in the beginning so as to make the bottom. which constitute an additional limitation on the tolerances for the preignition and burning periods..5. . 28 . The time periods should be observed with whatever burner or gas used.5.) 7) There should be no difficulty in carrying out the test exactly or directed with the gas burner provided. PROCEDURES: (cont. using city gas with the top of the burner about 2” below the bottom of the crucible. cool and weigh.) 8) Remove the burner and allow the apparatus to cool until no smoke appears..5. 29 . place in the dessicator. PROCEDURES: (cont. then remove the cover of the Skidmore crucible. Remove the porcelain crucible with heated tongs. ) 9) The total weight of the crucible plus beads and 10 grams of oil at start minus the weight of the crucible plus beads and carbon residue at finish equals loss of oil on grams. 30 .5. divided by 10 grams equals % of carbon residue. PROCEDURES: (cont. The 10 grams of oil minus loss in weight of oil equals carbon residue in grams.. of residue wt.) % of carbon residue weight of carbon residue 100% weight of oil wt. of crucible & oil wt. of crucible 31 . of crucible % carbon residue 100% wt. PROCEDURES: (cont. of crucible wt.5.. of crucible and carbon residue wt. of crucible & residue wt. DATA & RESULTS: Weight of crucible = _______________ Weight of oil = ___________________ % of carbon residue = ______________ Weight of carbon residue = __________ 3 2 .6. ANSWERS: 10. DISCUSSION: 11. CONCLUSION/RECOMMENDATION: 12. 7. SAMPLE COMPUTATIONS: 8. QUESTIONS : 9. REFERENCES: 33 . END 34 .