100 Short-Answer Calculation Questions on the Theoretical Part of the Oil Storage and Transportation Skills Competition

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50 short-answer questions. 1. What factors should be considered when selecting a line-cleaning medium? 2. What are the regulations regarding the inspection and calibration intervals for measuring instruments? 3. What are the requirements for taking measurements in dynamic oil tanks and static oil tanks? 4. What should be noted when measuring? What should be noted when taking temperature? 5. What measures can be taken to reduce oil evaporation losses? 6. What are the contents of the “four understandings” in equipment management? 　 7. What does the “three abilities” in the operation of equipment refer to? 8. What are the three levels of filtration for equipment lubrication? 9. How should frozen pipelines be handled? 10. What are the contents of the ten-step method for equipment maintenance? 11. What are the characteristics of a reciprocating pump? What are its main components? 12. Additives are used to improve the performance and quality of oils; therefore, using more additives can only bring benefits and no drawbacks, right? 13. What are the common viscosities of oils, and what are their units? 14. What is the function of lubricating oil? 15. Methods to eliminate vibration and noise during the operation of a centrifugal pump: 16. Briefly describe the method of switching between centrifugal pumps. 17. What tasks should be carried out on rainy days, and what precautions should be taken during operation? 18. What preparations are necessary before repairing a pump? 19. What are the principles for selecting a centrifugal pump? 20. Under what circumstances should a thermometer not be used? 21. Under what circumstances is it prohibited to use an oil dipstick? 22. What is the 30-second confirmation method? 23. What is the purpose of the correction values in the calibration certificates for oil gauges and thermometers? Give an example. 24. What inspections are carried out on storage tanks during routine checks? 25. What are the disadvantages of impurities in lubricating oil? 26. Why is it necessary to check the level of oil with high viscosity and high freezing point? 27. What is the acid value? What is its practical significance? 28. What does it mean if the liquid level in a stationary or discharging oil tank rises during regular level checks? 29. What are the reasons why a centrifugal pump won’t rotate, and how can this be addressed? 30. How does the viscosity of lubricating oil change during its processing? 31. What is the purpose of lubricant blending? 32. Why cannot a centrifugal pump be operated in reverse for long periods? 33. Briefly describe the working principle of a steam reciprocating pump. 34. What are the uses of additives, and what determines their dosage? 35. What consequences can occur if the temperature of oil additives is too low during blending? 36. What are the precautions to be taken when blending oils? 37. What are the disadvantages of water content in lubricating oil? 38. What is viscosity-temperature behavior? How is it measured? 39. What precautions should be taken when filling an empty tank with oil? 40. What are the causes of oil leakage from oil tanks? 41. What is the function of antifreeze agents? What is their range of application? 42. Why is it necessary to remove water from air tanks? How is this done? 43. What actions should be taken in snowy weather, and what precautions should be observed during operations? 44. Use characteristic curves to explain why the outlet valve must be closed when starting a centrifugal pump. 45. What are the advantages of steam reciprocating pumps over centrifugal pumps? 46. What are the reasons for a difference in oil intake and output volumes that exceeds the specified limits, and how should this be dealt with? 47. Under what circumstances do pipelines need to be treated? 48. What is the function of a safety valve? 49. How to use steam fire extinguishing equipment correctly? 50. What are the reasons for leaks in the heating coils of oil tanks? V. Calculation for Question 50: 1. An oil tank is undergoing both receiving and discharging operations simultaneously, with 70 cubic meters of oil being received per hour and 20 cubic meters per hour being discharged. Given that the capacity of the tank per meter is 444.4 cubic meters and the zero-point gauge level is at 2 meters, determine the gauge level at 10 o’clock. 2. The temperature of the oil in a tank is 50°C, and its volume V50 is 625.436 m³. Calculate the standard volume (ρ20 = 0.8543, f = 0.00078). 3. A certain pipeline has a diameter of φ89×5mm and a length of 100m; what is its volume? 4. Another pipeline has a diameter of φ108×4.5mm, and the flow rate of the liquid inside it is 50 cubic meters per hour; what is the velocity of the liquid? 5. If the pump displacement is 0.314 m³/s and the inner diameter of the pipe is 200 mm, what is the flow velocity of the oil inside the pipe?
6. Given that the flow rate of a certain oil product in a pipe with dimensions φ108×4.5 mm is 150 m³/h, calculate its flow velocity. 7. A tank receives distillates from two units; the flow rates from these units are 38 t/h and 41 t/h respectively, while the production rate of the unit itself is 36 t/h. The capacity of the tank per meter is 260 m3, and the density of the oil is 0.848. If the height measured at 8 o’clock is 4.3 meters, what should be the height measured at 18 o’clock? (Effects such as temperature are ignored.) 8. Given that the temperature of a certain oil is 30°C and its flow rate, as measured by a flow meter, is 856.903 m3, and its density at 20°C is 0.7450 t/m3, determine its mass at standard temperature. (f=0.00109, F=0.99850) 9. The flow rate Q of a certain centrifugal pump is 120 m3/h, the head H is 60 meters, and the density of the fluid being transported is 860 Kg/m3. The pump efficiency η is 53%; determine the shaft power of this pump. 10. It is known that a pipeline is 1000 m long and has an inner diameter of 100 mm. Determine the amount of oil that can be stored in this pipeline. 11. A centrifugal pump with a diameter of 4.5 m is used to pump clean water at room temperature under atmospheric pressure. The resistance loss in the suction pipeline is given as hA-S = 0.5 m. What is the allowable geometric installation height when the pump is installed in an area where the atmospheric pressure head is Pa/r = 10.32 m? (The saturated vapor pressure of clean water is Pt/r = 0.24 m.) 12. It is known that a tank can receive oil at a rate of 35 m3/h. The safe operating height for this tank is 10.30 m, its capacity per meter is 110 m2, and the oil level inside the tank is currently at 6.5 m. When will the tank reach its safe capacity? 13. A temperature measuring instrument has a measurement range of 200–700°C. The maximum absolute error observed during calibration of this instrument is ±4°C. Determine the accuracy class of this instrument. 14. At a temperature of 50°C, the volume of a certain oil product is 526.436 m3, with a density of 0.8543 t/m3. Determine the standard volume of this oil product. (The K value is 0.9767, as determined from the density and temperature of the oil.) 15. A tank has a volume of 158.362 m3 per meter; when 70 m3 of oil are in the tank, the level indicated by the zero mark on the gauge is 2 meters. If the amount of oil remains unchanged, what will be the level indicated by the gauge at 8 o’clock? 16. Oil volume calculation: 25# transformer oil, transferred from one pump room to a tank in another pump room; the front gauge reading of the oil tank is 0.820 m, and the rear gauge reading is 7.541 m ； The density at the front gauge is 0.8717 at a temperature of 28°C, while the density at the rear gauge is 0.8721 at a temperature of 38°C. The oil volume in the flowmeter is 482.61 tons. Question: (1) What is the amount of oil collected? (2) What is the profit or loss? 17. Oil volume calculation: TSA32 is transferred from Pump House A to a tank in Pump House B. The front gauge reading of the oil tank is 0.724 m, and the back gauge reading is 6.452 m. The density at the front gauge reading is 0.8675 at a temperature of 16°C, while the density at the back gauge reading is 0.8678 at a temperature of 24°C. The oil volume indicated by the flow meter is 244.2 t. Question: (1) What is the amount of oil received? (2) Profit and loss? 18. A tank receives distillate at a rate of 35 m3/h for 24 hours; its cross-sectional area is 96 m2. How high can the liquid level rise? 19. Given that the pump’s flow rate is Q = 70 m3/h, the head it generates is H = 65.84 meters of water column, and its shaft power is N = 18.2 kW, determine the pump’s useful power and efficiency. (r=1000kg/m3) 20. Given that the effective power of the pump is 75 kW, η=54%, and K=1.1, what is the minimum power of the motor required? 21. A steel pipe is 200 meters long at -10°C. What will be its length when the temperature rises to 170°C? (The expansion coefficient of the pipe is α=1.2×10-5.) 22. Tank A has a diameter of ΦA=15 m and a safe height of 14 m; the height of the oil in this tank is hA=10 m. Tank B has a diameter of ΦB=20 m and a safe height of 18 m; the height of the oil in this tank is hB=5 m. Both tanks are at the same horizontal level, and the oil type in both tanks is the same. After the oil starts flowing automatically from Tank A to Tank B, what will be the oil levels in each tank? 23. A pump is used for transferring oil. The average pressure in the semi-finished product tank is 0.06 MPa (gauge pressure), while the average pressure in the finished product tank is 0.3 MPa (gauge pressure). The density of the oil is 0.82 g/cm³. The lowest liquid level in the semi-finished product tank is 4 m, and the highest liquid level in the finished product tank is 12 m. The total resistance loss in the entire pipeline system is Σhf=16 m. The flow rate of oil into the tanks is 1.5 m/s. What is the head required by the pump? 24. A 100Y-120 pump has an impeller diameter of 310 mm and a flow rate of 120 m³/h. If it is desired to increase this flow rate to 100 m³/h, what should be the new diameter of the impeller? 25. A 150Y–81B pump has an impeller diameter of 206 mm and a head of 49 m. Due to changes in the processing requirements, the required head is now 81 m. Is an impeller with a diameter of 260 mm sufficient to meet these requirements? 26. A oil tank contains 4000 tons of oil with a residue value of 0.7%. It is necessary to obtain 10000 tons of oil with a residue value of 0.4%. How can the residue value of the oil added be calculated? 27. A certain oil tank already has a gauge height of 6 m. Oil is being poured into the tank at a rate of 80 m³/h, starting from point O. The safe maximum height of the tank is 13.00 m, and its capacity per meter is 90 m². Is it possible to continue pouring oil at time 8? 28. There are two tanks in a railway tank car: Tank A contains 40 tons of oil with a density of 0.8800, while Tank B contains 10 tons of oil with a density of 0.8700. What is the density of the mixture? 29. There is a 60 m³ oil tank that is already full with 50 tons of oil. Its alkali number is 17.5, which is not acceptable; it needs to be reduced to 12.5. What actions should be taken? 30. Given a mixing ratio of A:B = 40:60 for two components, there is a tank with a capacity of 200 m3, an actual height of 6.4 m, and an additive addition rate of 10%. Please prepare the oil for this tank. (Safe height = tank height × 90%, specific gravity of the oil d204 = 0.9, specific gravity of the additive d204 = 1.0) 31. Given that the rated parameters of the pump are Q = 200 m³/h and n = 2950 revolutions per minute, and assuming that a motor with a speed of n = 1475 revolutions per minute is used to drive the pump, determine the actual flow rate of this pump. 32. The typical amount of anti-emulsifier used is 15 g/1000 L. How much anti-emulsifier is needed to produce 100 tons of automotive engine oil? (ρ_vapor = 0.85 t/m3) 33. The residual carbon content of the light components is 0.4%, while that of the heavy components is 2.2%. If an oil product with a residual carbon content of 0.8% is to be obtained, what is the blending ratio? 34. It is known that a fluid flows at a velocity of V = 1.48 m/s through a pipe into a tank; the cross-sectional area of the tank is 100 times that of the pipe. What is the rate of rise of the liquid level in the tank? 35. A fluid flows through pipes of different diameters. The flow velocity in the thicker pipe with dimensions Φ89×4 is 1 m/s. What is the flow velocity in the thinner pipe with dimensions Φ57×3.5?
36. A storage tank is used to discharge two types of oil: component A and component B. The flow rates are 23 t/h for component A and 21 t/h for component B. When both are discharged simultaneously, the total flow rate is 55 t/h. It is known that the capacity of the tank per meter of height is 395 m³, and the density of the oil is 0.98. At present, the oil level is at a height of 3.5 m. How many hours will it take for the oil level to drop to the lower limit (which is 1 m)?
37. Calculate the specific weight of air at 80°C and 1.2 atmospheres of pressure.
38. It is necessary to prepare anti-rust instrument oil. The required proportions are: 1% heptadecenylimidazole, 1.5% zinc naphthenate, 0.2% benzotriazole, and 0.3% pentachlorobiphenyl. The remainder should be filled with Type 8 aviation lubricating oil. If 10 tons of anti-rust instrument oil needs to be prepared, how much Type 8 aviation lubricating oil is required? 39. A certain finished oil tank has a diameter of 8.2 m and a safe height of 7.4 m. The specific gravity of the oil inside the tank is d = 0.9. Since the quality of the oil is unsatisfactory, circulation is required to address this issue. How long will it take to carry out this circulation using a pump with a discharge capacity of 40 t/h? 40. Generally, 5–10% sodium petroleum sulfonate can be added to rust-inhibiting greases as an agent for sealing and preventing rust. How much sodium petroleum sulfonate is needed to produce 20 tons of such sealing rust-inhibiting oil? 41. Before putting a certain oil tank into use, it needs to be pressure-tested. After the tank is filled with water, a pressure gauge located 1 meter above the ground shows a reading of 1.5 kilograms/cm2. At this time, the atmospheric pressure is 1 kilogram/cm2. What are the pressures at the top and bottom of the tank? (The oil tank specifications are Φ28400×15800). The team processed 257 tons of refined oil, consuming 210 kWh of electricity and 3.5 tons of steam. The cost is 0.45 yuan per kWh for electricity and 90 yuan per ton for steam; other energy costs are ignored. What is the overall cost per ton of oil? 　43. The centrifugal pump is model 100Ya-100, and the flow velocity of the medium at the inlet is 1.5 m/s. What is the displacement of this pump? 44. The volumetric flow rate of a certain oil pipeline is 200 m³/h, and its specific gravity is 0.857. What is its mass flow rate? 45. It is known that the viscosities of oils composed of components A and B at 100°C are 6.5 centistokes and 12.5 centistokes respectively. It is necessary to prepare an oil with a viscosity of 12 centistokes by blending these two components; determine the blending ratio of A and B. 46. A tank contains 250 m3 of oil, with a total weight of 216.8×103 kg. What is the density of this oil? 47. The exit flow velocity of a certain pump is 2.45 m/s, and the diameter of the outlet pipe is Dg250. What is the volumetric flow rate of this pump per hour? 48. For a pipe with a cross-sectional area that varies along its length, where D1=200mm and d2=150mm, and the fluid flow velocity is W2=1.5 m/s, what is the flow velocity in the larger pipe? 49. A pump was originally designed to operate at 1450 r/min with a head of 20 m. If the speed of this pump is increased to 2900 r/min, what will be its new head? 50. A tank currently contains 200 tons of a certain refined oil, and it is necessary to replace this with 1000 tons of another type of oil. If the concentration of additives in the first oil is A: 0.5% and B: 1%, then for the 1000 tons of oil to be replaced, the additive composition should be A: 1%, B: 1%, C: 0.5%. How much more of A, B, and C is needed? How many tons of base oil are required? Short answer: 1. Answer: ① When the cleaning medium is mixed with the oil, no flammable or explosive gases are produced ； ②After sweeping, the medium or the mixture of medium and oil is easier to handle ； ③No condensation blockage occurs when the scanning medium comes into contact with oil products ； ④The pressure of the cleaning medium must be greater than the flow resistance of the oil in the pipeline ； ⑤The source of the scanning medium is reliable, and its destination for scanning is appropriate. 2. Answer: Measuring instruments under Class A management refer to those that are subject to mandatory calibration, and must be calibrated at intervals specified in the relevant calibration regulations ； Measurement instruments under Class B management refer to those used for transferring measurements between workshops, and they are calibrated at intervals specified in the calibration regulations. 3. Answer: For dynamic oil tanks, the oil level gauge should be measured every 2 hours (at two points). For tanks without a dynamic oil level gauge, the oil level should be checked once per shift by the personnel responsible for maintaining that tank. 4. Answer: (1) Gauge inspection: a. The length of the oil gauge should meet the requirements of the measurement range ； b. The minimum scale division of the oil dipstick is 1 mm, and it is accompanied by a calibration certificate and a correction table ； c. Before measuring the oil dipstick, determine the total height of the oil tank to estimate the approximate oil level at the time of measurement, and then go up to the tank to take the reading ； d. Gently open the gauge hole cover, and insert the oil dipstick into the tank along its self-guiding groove ； e. The oil dipstick should be checked twice; the difference between the two readings should not be more than 1 mm. If it exceeds 1 mm, the measurement must be taken again. f. When taking the measurement, the liquid level in the tank must be stable; the measurement should be taken after the liquid level has remained stable for 2 hours. g. After the operation, clean the area around the dipstick hole thoroughly. (2) Temperature measurement: a. Use a calibrated mercury thermometer ； b. The thermometer should be checked before use, and replaced promptly if any damage is found ； c. The thermometer must be securely fixed inside the temperature measuring tube, with the scale facing outward ； d. After the above tasks are completed, temperature measurement can be carried out inside the tank ； e. Gently open the cover of the measurement hole, and slowly lower the temperature measuring tube at a speed not exceeding 0.5 m/s, with a descending speed not exceeding 1 m/s; f. The temperature measuring tube should be submerged in the middle of the oil, and it must remain there for at least 15 minutes ； 　g. When taking a reading, the line of sight must be perpendicular to the thermometer; the reading process should not exceed 10 seconds. The temperature should be read quickly, starting with the decimal part followed by the whole number. The reading error must not exceed 0.5°C. After taking the reading, pour the oil contained in the box back into the tank. 5. Answer: a. Reduce the temperature fluctuations of the oil inside the tank ； b. Proper selection of coatings for oil tanks ； c. Take insulation measures for the oil tank ； d. Reduce the gas space on the oil surface ； e. Collect the gas of the exhaled oil products. 6. Answer: Understand the principles, structure, performance, and applications. 7. Answer: Able to operate, maintain, perform minor repairs, and handle common faults. 8. Answer: From the large oil tank to the device’s large tank for filtration, from the device’s large tank to the oil jug for filtration, and from the oil jug to the machine pump’s fueling point for filtration. 9. Answer: ① To thaw locally frozen pipelines, use steam to warm them along the pipe walls ； ②If there is a heating line available, use it to steam and melt the substance ； ③When the above methods are ineffective for freezing the entire pipeline, it should be disconnected in sections and then melted using steam ； ④For pipelines that have been frozen for a long time, direct steam purging is prohibited; they must be treated in sections. 10. Answer: Adjusting, tightening, lubricating, corrosion protection, cleaning. 11. Answer: Characteristics of a reciprocating pump: The flow rate of the pump does not change as the head increases, and its efficiency is also higher than that of a centrifugal pump. It has self-priming capability, and it consists of a pump body, pistons, and suction and discharge valves. 12. Answer: This statement is incorrect. Due to the synergistic effects between additives, there is a certain range within which the base oil is sensitive to these additives; adding too much of them results in waste. In some cases, an excessive amount of certain additives can have the opposite effect – not only does it degrade certain properties of the oil, but it also leads to higher fuel consumption and more carbon buildup as side effects. 13. Answer: There are mainly the following types: Engler viscosity, which is dimensionless ； Dynamic viscosity, unit: poise, centipoise ； Kinematic viscosity: The unit is St, centistokes ； Reynolds viscosity: Unit: seconds ； Shear viscosity: Unit: seconds. 14. Answer: Lubrication, cooling, flushing, sealing, vibration damping, load relief, and protection. 15. Answers: (1) Tighten the anchor bolts; (2) Align or replace the pump shaft; (3) Repair the bearing bushes or adjust the clearance; (4) Perform alignment; (5) Take measures based on the cause of cavitation ； (6). Try to eliminate this imbalance. 16. Answer: 1) After completing the preparations prior to starting the standby pump, open the inlet valve of the pump; 2) Start the motor of the standby pump and wait 1-2 minutes, then check that the pressure at the pump’s outlet as well as the current levels are normal, after which slowly open the outlet valve of the standby pump. 3) While slowly opening the outlet valve of the standby pump, gradually close the outlet valve of the pump that was in operation earlier, in order to minimize fluctuations in flow rate and pressure. 4) Once the standby pump is operating properly, shut down the pump that has been replaced. 17. Answers: 1) On rainy days, cover the light-transmitting holes and inspection openings on the oil tank to prevent rainwater from entering; 2) For oil tanks equipped with drainage elbows, it is necessary to open the drainage valves promptly during rainy days to drain the rainwater from the top of the tank, and keep an eye on the liquid level while checking regularly whether the drainage elbows are leaking; 3) For pipelines carrying oils with high freezing points that do not have good insulation, it is important to control the transmission pressure and flow rate to prevent excessive heat loss from the pipelines, which could cause the oil to solidify; 4) Check the drainage systems around equipment and buildings to ensure there are no signs of subsidence; 5) When working outdoors, wear raincoats – the use of umbrellas is strictly prohibited; 6) During strong winds and heavy rain, take precautions to prevent the insulating sheets on equipment from falling and causing injuries; 7) Work on the top of the tank is strictly prohibited during thunderstorms or when wind speeds exceed level 6. If work must be done in such conditions, two people should work together and effective safety measures must be taken. 18. Answers: (1) Clean the pump thoroughly and close the inlet and outlet valves; (2) Open the vent valve of the pump to drain all the medium inside it; (3) Allow the hot oil pump to cool down to room temperature; (4) Cut off the power supply; (5) Notify relevant production personnel. 19. Answer: 1) It must meet the process requirements; 2) It must operate reliably – aspects such as suction capacity, the tightness of the sealing in the plate box, and the strength of the components all need to be ensured. It should also be easy to control, maintain, and repair when in use; 3) Cost-effectiveness: low cost, small size, light weight, efficient operation, and minimal investment required ； (4). Flexibility: Wide range of applications to meet various uses and changing operating conditions; (5). Special requirements: Such as explosion protection, corrosion resistance, and tolerance to changes in air pressure and temperature at the location of use. 20. Answer: ① There is a breakage in the mercury column inside the capillary tube ； ②The scale is unclear ； ③The temperature-sensitive bulb is cracked ； ④There is no certification certificate. 21. Answer: ① The scale on the tape is blurred or the numbers have fallen off ； ②Twisting, bending, and splicing of the scale band ； ③Damage to the tip of the ruler hammer ； ④There is no certification certificate. 22. Answer: ① Verify whether all labor protection equipment has been worn ； ②Verify whether the actions taken for this operation comply with the operating procedures and production discipline ； ③Verify that the equipment and process flow used for this operation are accurate ； ④Check whether the surrounding environment is safe and whether safety measures have been implemented. 23. Answer: The correction values in the calibration certificates for oil gauges and thermometers are used to adjust the measured values, bringing them closer to the true value, reducing measurement errors, and improving the accuracy of measurements. For example, with a certain dipstick, when measuring the oil level, the reading obtained is 2493 mm. If the correction value lies between 2000 mm and 3000 mm, the correction amount is +2 mm; thus, the actual measured value is 2493 + (+2) = 2495 mm. 24. Answer: ① Check the changes in the liquid level, temperature, and pressure of the storage tank ； ②Check whether the process for monitoring the operating condition of the storage tank is correct ； ③Check whether the storage tank venting system is unobstructed, and whether the safety and waterproofing facilities are in good condition ； ④Check whether there is any leakage, dripping, or seepage from the storage tank ； ⑤In winter, check for freezing conditions as well as the operation of heat tracing for condensate removal. 25. Answer: Impurities refer to particles and precipitates that do not dissolve in oil. The presence of such impurities in lubricating oil increases wear on mechanical components, leads to the formation of carbon deposits, and can cause blockages in the oil passages and filters. 26. Answer: (1) Since it is difficult for the measuring rod with a plumb bob to reach the bottom of the oil tank, this can lead to errors in measurement; (2) The oil marks on the measuring rod are hard to remove after measurement. 27. Answer: The acid value is the number of grams of KOH required to neutralize 1 gram of lubricant. Practical significance: (1) The content of acidic substances in the oil can be determined based on the acid value ； (2) Refining degree of the reaction oil product ； (3) The corrosion properties of the oil product on metals can be inferred ； (4) The acidic substances produced by oxidation deterioration can easily clog the lubrication system. 28. Answer: (1) Oil leakage; (2) Leakage in the heating tube; (3) Rising temperature of the oil. 29. Answer: Reasons: (1) The oil stored inside the pump has solidified; (2) There is pressure at the pump outlet; (3) Damaged components; (4) Shaft deformation. Treatment methods: (1) Preheating; (2) Pressure release; (3) Replacing components; (4) Replacing or repairing the shaft. 30. Answer: After dewaxing, the viscosity of the oil product increases significantly; after solvent refining, the viscosity decreases to some extent, while it remains essentially unchanged after clay refining. 31. Answer: The purpose of blending is to combine several lubricant components with appropriate additives in order to produce products that meet various quality standards and are suitable for different applications. 32. Answer: When a centrifugal pump is reversed at low speed for a short period of time, it generally does not cause any harm; however, reversing it at high speed for an extended period is not allowed. (1) The various components of the pump are designed for normal operation of the pump within its efficient range; if it operates at high speed in reverse, certain components may be subjected to excessive stress, disrupting the balance of forces and affecting the sealing gaps. (2) In some pumps, the impeller and other components are secured using nuts depending on the direction of rotation of the pump. If the pump operates at high speed in reverse for an extended period, these securing nuts may loosen or even fall off, leading to accidents. 33. Answer: Driven by the cylinder piston, the oil cylinder piston moves back and forth. When the volume of the oil cylinder increases, a low pressure is created inside it; the discharge valve closes while the inlet valve opens, allowing liquid to enter the cylinder from the pump’s inlet. When the volume of the oil cylinder decreases, a high pressure is generated inside it; at this point the suction valve closes and the discharge valve opens, causing the liquid to be discharged from the pump’s outlet. As the cylinder piston continues to move back and forth, the liquid is continuously drawn in and discharged. 34. Answer: (1) Requirements for the use of refined oils; (2) Performance characteristics of additives; (3) Properties of base oils and their sensitivity to additives. 35. Answer: (1) The additives cannot dissolve fully in the lubricating oil, which affects the blending efficiency and the quality of the oil; (2) During the transfer of these additives, they tend to stick to the pipelines and equipment, thereby affecting the amount of additives that can be added. 36. Answer: (1) The mixing temperature (of the base oil and additives) must be kept within the specified range; (2) The additives should be added to the tank from an empty line so that they can spread thoroughly ； (3) Maintain a circulation time of 10–15 minutes before and after adding the additive to warm the lines and flush the pipelines. (4) After adding the additive, use air to thoroughly clean the lines or ensure adequate circulation in order to guarantee the correct dosage. (5). Ensure the mixing time. 37. Answer: Water can destroy the oil film, causing foam to form. This deteriorates the lubricating properties, reduces the viscosity of the oil, increases its freezing point, and causes additives to precipitate and become ineffective, thereby affecting the oil’s performance. Additionally, water promotes corrosion of machine components. Therefore, no water should be present in lubricating oils. 38. Answer: The characteristic by which viscosity changes with temperature is known as the viscosity-temperature behavior of lubricating oil. The indicators used to assess the quality of a oil’s viscosity-temperature behavior are the viscosity ratio or viscosity index. 39. Answer: When receiving oil into new tanks, or tanks that have been overhauled or cleaned, it is necessary to pay attention to the following points: (1) Ensure that the screws on all manholes are tightened properly; (2) Check for leaks at the manholes once the oil reaches those areas; (3) As the liquid level rises and pressure increases, constantly check the bottom and walls of the tank for any signs of leakage. 40. Answer: (1) Lack of responsibility in work, failure to conduct inspections, or leaving one’s post in violation of rules ； (2) Lack of insulation facilities, resulting in frozen and cracked oil pipes or valves ； (3) Oil storage and transmission equipment is in poor condition due to lack of maintenance over time ； (4) Poor quality of maintenance work ； (5). Inadequate handovers and poor communication during shift changes ； (6) Leave the site during water cutting operations. 41. Answer: Function: To lower the freezing point of oils and improve their low-temperature fluidity. Application scope: Machine oils, engine oils, and certain types of low-freezing-point oils.
42. Answer: Since air is stored in the air tank for a long time, water in the air cools down and accumulates at the bottom of the tank. When purging the pipeline with air, this water gets carried into the tank, affecting the quality of the oil. Operating steps: Open the drain valve at the bottom to remove the accumulated water from the air tank. Then, operate the control switch of the drain valve several times until no more water is discharged. Finally, close the drain valve. 43. Answer: (1) On snowy days, cover the light-transmitting openings and manholes on the tank tops to prevent snow from entering. (2) For pipelines transporting oils with high freezing points that lack proper insulation, it is necessary to monitor the pump’s discharge pressure and flow rate to prevent excessive heat loss from the pipelines, which could cause the oil to solidify. (3) Promptly clear away any snow accumulation in the tank area, on equipment, and along work pathways. (4) During windy and snowy weather, outdoor work must be conducted with care to prevent injury from flying sheets of metal. (5) In heavy wind and snow conditions, if equipment or ladders become icy, operations on tank tops may be suspended upon approval from relevant authorities. Should it be absolutely necessary to go onto the tanks, two people must work together while taking effective safety measures. 44. Answer: According to the characteristic curve of centrifugal pumps, generally as the flow rate increases, the power required also increases, which means the load on the motor rises. When the flow rate is zero, the power consumption is at its minimum. Therefore, in order to ensure the safe start of the motor, it is necessary to close the pump outlet valve during operation. 45. Answer: (1) Reciprocating pumps have high efficiency, usually 10--20% higher than that of centrifugal pumps. (2) Reciprocating pumps have a better suction capacity than centrifugal pumps. (3) They are capable of transporting liquids with high viscosity. (4) If the pipelines, as well as the seals and strength of the pump, are of good quality, steam reciprocating pumps can theoretically achieve very high delivery pressures. 46. Answer: Reasons: ①. There are errors in measurement of level and temperature before and after oil loading/unloading from the tank ； ②.The oil pipeline wasn’t thoroughly purged during flushing ； ③.During transportation, oil leaks into other pipelines or oil tanks ； ④. There are errors in oil product measurement ； ⑤.The tank volume table is incorrect, or the tank is being used past its calibration date ； Handling: ①. Before and after oil is received into the tank, measurements and temperature checks must be carried out carefully as prescribed ； ②. After the oil transfer is complete, the pipeline must be thoroughly cleaned ； ③. Check whether the valves connecting the oil transfer pipeline to other pipelines and oil tanks are properly closed or leak internally ； ④.Recalculate the oil receipt and dispatch volumes ； ⑤. Check whether there are any errors in the volume table or whether the oil tank needs to be calibrated regularly. 47. Answer: The displacement and purging of the oil contained within the pipeline when maintenance or welding work is required on it ； The replacement process required when the type of product transported or the quality of the oil being transported needs to be changed in the same pipeline ； Perform thorough cleaning before and after oil transfer through pipelines with empty lines, as well as continuous cleaning and purging to prevent freezing and condensation in winter. 48. Answer: When the pressure of the medium exceeds the specified value, the safety valve can discharge fluid automatically, thereby preventing the equipment or pipelines from being damaged. Once the pressure returns to normal, the valve closes automatically, allowing normal operation to resume. 49. Answer: Steam fire extinguishing is a type of smothering fire extinguishment; steam is released into the burning area, reducing the oxygen level there to such an extent that the fire is extinguished. It cannot be used for some combustion materials whose auto-ignition temperature is lower than the steam temperature ； Use some volatile solvents with caution. When spraying, cut the flame vertically, aiming at its base to separate the burning material from air; otherwise, the steam temperature will cause flammable substances to vaporize in large quantities, leading to an expansion of the flame. Also, do not spray steam on people to avoid burns. 50. Answer: (1) Improper operation; the condensate water was not completely drained before heating, resulting in water hammer ； (2) The flange gasket has not been replaced in a timely manner due to wear and tear over time or aging ； (3) Pipeline corrosion and leakage ； (4) Weld quality does not meet requirements ； (5) In winter, the temperature inside the tank is low, causing the heating coil to freeze and crack. V. Answers to the calculation questions 1. Solution: (1) The total volume of oil produced in 10 hours is (70–20)×10 = 500 (m3). (2) The height of the oil layer after 10 hours is 500/444.4 = 1.1 (m). (3) The level of the oil gauge at 10 o’clock should be 2 + 1.1 = 3.1 (m). Answer: The oil gauge reading at 10 o’clock is 3.1 m. 2. Solution: V20 = Vt = 625.436× = 610.801 (m3); Answer: The standard volume is 610.801 (m3). 3. Answer: The volume of the pipeline is 0.0049 m3. 4. Solution: V = 50 / (0.0077 × 3600) = 1.80 m/s. Answer: The flow rate of the liquid in the pipe is 1.8 m/s. 5. Answer: The flow velocity of the oil inside the pipe is 10 m/s. 6. Solution: V = Q/S = 150 / (3.14 × 0.05² × 3600) = 5.3 m/s. Answer: The flow velocity of the liquid inside the pipe is 5.3 m/s. 7. Solution: h = 4.3 + (260 × 0.84) = 6.27 m. Answer: At 18:00, the oil level should be 6.27 m. 8. Solution: V20 = 856.903 × = 847.563 m³. m = V20 × ρ20 × F = 847.563 × 0.7450 × 0.98850 = 624.173 (t). Answer: The mass at standard temperature is 624.173 tons. 9. Solution: N = Q * H * γ / 3600η = 120 * 60 * 860 / 367 * 0.53 = 32 KW. 10. Answer: The oil volume stored in the pipeline is 7.85 m³. 11. Solution: =10.32-0.24-0.5-4.5=5.08m. Answer: The allowable geometric height for installation is 5.08 m. 12. Solution: 10.30 – 6.5 = 3.8 (m). 3.8 × 110 = 418 m³. 418 / 35 = 11.9 (hours). Answer: It will take 11.9 hours to reach a safe level. 13. Solution: (1) The maximum relative percentage error of this instrument is δ = Δ/N × 100% = ±4/(700–200) × 100% = ±0.8%. (2) Since the maximum relative error of this instrument exceeds ±0.5%, its accuracy class is 1.0. Answer: The accuracy class is 1.0. 14. Solution: V20 = K·Vt = 0.9767×625.436 = 610.863 m3. Answer: The standard volume of this oil is 610.863 m3. 15. Solution: (1) The total volume of oil collected in 8 hours is: 8 × 70 = 560 m³. (2) Converting 560 cubic meters gives 560158.362 = 3.536 m. (3) At 8 o’clock, the oil level should be 2 + 3.536 = 5.536 m. 　Answer: The oil level at 8 o’clock should be 5.536 m. 16. Solution: Given that when the front gauge reading is 0.820 m, Vt = 67.834 m3; and when it is 7.541 m, Vt = 621.278 m3, with f = 0.00074.
(1) k = 1 – f(t – 20) = 1 – 0.00074 × (28 – 20) = 0.99408.
V20 = k · Vt = 0.99408 × 67.834 = 67.432 m3.
The amount of oil in the front tank = V20 · (ρ20 – 0.0011) = 67.432 × (0.8717 – 0.0011) = 58.706(t).
(2) k = 1 – f(t – 20) = 1 – 0.00074 × (38 – 20) = 0.98668.
V20 = k · Vt = 0.98668 × 621.278 = 613.002 m3.
The amount of oil in the rear tank = V20 · (ρ20 – 0.0011) = 613.002 × (0.8721 – 0.0011) = 533.925(t).
(3) The amount of oil collected = 533.925 – 58.706 = 475.219(t).
The excess or deficit = 475.219 – 482.61 = –7.391(t). Answer: The oil collection amount is 475.219 t ； The profit and loss is –7.391t. 17. Solution: (1) k = 1 – f(t–20) = 1 – 0.00075 × (16–20) = 1.003. V20 = k · Vt = 1.003 × 36.276 = 36.385 m³. The oil volume in the front tank is m = V20 / (ρ20 – 0.0011) = 36.385 × (0.8675 – 0.0011) = 31.524 (t). (2) k = 1 – f(t–20) = 1 – 0.00075 × (24–20) = 0.997. V20 = k · Vt = 0.997 × 321.58 = 320.615 m³. The oil volume in the rear tank is m = V20 / (ρ20 – 0.0011) = 320.615 × (0.8678 – 0.0011) = 277.877 (t). (3) Oil quantity collected: 277.877 – 31.524 = 246.353 (t). Excess/deficit: 246.353 – 244.2 = +2.153 (t). Answer: The oil collection amount is 246.353 t ； The profit and loss is +2.153t. 18. Solution: The rise in height h = (35/96) × 24 = 8.75 m. Answer: The liquid level can rise by 8.75 m. 19. Answer: The effective power of the pump is 12.55 kW ； The pump’s efficiency is 69%. 20. Solution: N = (Ne/η)K = (75/0.54) × 1.1 = 152.8 kW. Answer: A motor with a power of 152.8 kW should be used at minimum. 21. Solution: L2 = L1 × = 200 × = 200.432(m). Answer: The length of the pipeline is 200.432 m. 22. Answer: The oil level in each tank is 6.8 m. 23. Solution: H = (12*0.82 + 0.3*9.8) + Σhf – (0.06*9.8 + 4*0.82) = 12.78 + 16 – 3.87 = 24.91 m². 24. Answer: The diameter of the impeller after cutting is 258.3 mm. 25. Solution: (260/206) * 49 = 61.8 m. Answer: It is no longer possible to pump in more oil. 28. Solution: m = (40×0.88 + 10×0.87) / (40 + 10) = 0.8780 g/cm³. Answer: The density of the mixture is 0.8780 g/cm³. 29. Solution: (1) Since it’s already full, some oil must be poured out. First, we need to calculate the amount of oil to be poured out. (2) The formula is GA = 【(X – XB) / (XA – XB)】 × 100%. Here, X represents the target value for the alkali number: X = 12.5. XA is the value of the base oil in the blank sample: XA = 0. XB is the actual value of the oil inside the tank: XB = 17.5. GA represents the percentage of the base oil in the mixed oil. Using the formula: GA = 【(X – XB) / (XA – XB)】 × 100% = 【(12.5 – 17.5) / (0 – 17.5)】 × 100% = 26.8%. Therefore, 50 × 26.8% = 13.4 tons of oil need to be removed. In other words, 13.4 tons of base oil should be added back to keep the alkali number around 12.5. 30. Solution: Given that A:B = 40:60, the actual height of the oil tank is 6.4 m. The amount of additive to be added is 10%. The specific gravity of the oil at d204 is 0.9, while that of the additive is 1.0. (1) The safe height of the oil tank: 6.4 × 90% = 5.76 m. (2) The total amount of oil at a height of 5.76 m is 5.76 × (200/6.4) × 0.9 = 162 tons. Therefore, the amount of additive required is 162 × 10% = 16.2 tons. The corresponding level of the additive in the tank should be 16.2 ÷ 1.0 ÷ (200/6.4) = 0.5184 m ≈ 0.52 m. Therefore, 5.76 – 0.52 = 5.24 m. (3) Calculate the amount of oil from each component that enters the dipstick: For Component A, it is 5.24 × 40% = 2.1 m ； Component B oil: 5.76 – 2.1 = 3.14 m. Answer: The oil inlet length for Component A is 2.1m, and for Component B it is 3.14m. 31. Answer: The actual flow rate of this pump is 100 m³/h. 32. Solution: (1) V = M/ρ = 100/0.85 = 117.65 m3. (2) 117.65 × 15 = 1765 g = 1.8 kg. Answer: 1.8 kg of demulsifier needs to be added. 33. Solution: M = (2.2 – 0.8) / (0.8 – 0.4) = 3.5. Answer: The mixing ratio is 3.5:1. 34. Solution: V = 1.48/100 = 0.00148 mm/S.
35. Solution: V = 4*(89 – 2*4)²/(57 – 2*3.5)²*4 = 10.50 M/S.
36. Solution: The total volume of oil that needs to be delivered to reach the lower limit is 395×(3.5 – 1) = 987.5 (m³). The volume of oil delivered per hour is (55 – 23 – 21)/0.98 = 11.224 (m³). The time required is 987.5 ÷ 11.224 = 88 hours. Answer: It will take 88 hours for the tank to reach the lower limit. 37. Solution: At 0 degrees Celsius and 1 atmosphere of pressure, the density of air is 1.293. At 1.2 atmospheres of pressure and 80 degrees Celsius, the density is 1.293*1.2*(273/(273+80)) = 1.2038. Solution: (1) 100% – 1% – 1.5% – 0.2% – 0.3% = 97%. (2) 10t × 97% = 9.7t. Answer: 9.7 tons of aviation lubricant type 8 are required. 39. Solution: From the given information, the safe capacity of the oil tank can be calculated as follows: V = πgh² = πd²/4 × H = (3.14 × 8.22)/4 × 7.4 = 390.6 m³. The weight of the oil, G, is then given by G = V × ρg = 390.6 × 0.9 = 351.9 tons. Therefore, the circulation time t is equal to G/40 = 351.9/40 = 8.8 hours. Answer: 8.8 hours are required. 40. Solution: ① The minimum amount to add is 20t × 5% = 1t. ② The maximum amount to add is 20t × 10% = 2t. Answer: 1–2t of sodium petroleum sulfonate needs to be added. 41. Solution: From P2 = P1 + (Z1 – Z2)r, it can be determined that the pressure at the bottom of the tank is: P_bottom = 1.5 + 1/10000 = 1.6 kg/cm2. The pressure at the top of the tank is: P_top = 1.5 + (1 – 15.8) × 1000/10000 = 0.02 kg/cm2. Answer: The pressure at the top of the tank is 0.02 kg/cm2　 ； The pressure at the bottom of the tank is 1.6 kg/cm2. Solution: [210×0.45 + 3.5×90] ÷ 257 = 1.59 (yuan per ton of oil). Answer: The comprehensive energy consumption for oil processing is 1.59 yuan per ton of oil. 43. Solution: A = 1/4πD2 = 1/4 × 3.14 × 0.1 × 0.1 = 0.00785 (m2). Q = AV = 0.00785 × 1.5 = 0.0118 (m3/s). Answer: The pump’s displacement is 0.0118 m3/s. 44. Solution: Weight flow rate = 200 × 0.857 = 171.4 (t/h). Answer: The weight flow rate is 171.4 t/h. 45. Solution: n = (C – C2) / (C1 – C2), where n is the percentage by volume of the high-viscosity component. C = 1000 × lg(g(V + 0.8)); C1 = 1000 × lg(g(V1 + 0.8)); C2 = 1000 × lg(g(V2 + 0.8)). 0.8 is a coefficient, V represents the viscosity of the oil to be blended, V1 is the viscosity of the high-viscosity component oil, and V2 is the viscosity of the low-viscosity component oil. Therefore, n = 94.34%, meaning that the proportion of Component B in the mixture is 94.34% ； The proportion of Component A oil is 100% – 94.34% = 5.66%. Answer: Component A oil accounts for 5.66%, while Component B oil accounts for 94.34%. 46. Solution: ρ = m/v = 216.8×10³ kg/250 m³ = 867.2 kg/m³. Answer: The density of this oil is 867.2 kg/m³. 47. Solution: V = π(d/2)² × V1 × 3600 = 3.14 × (250÷1000)² × 2.45 × 3600 = 432.7 m³/h. Answer: The volumetric flow rate of this pump is 432.7 m³/h. 48. Solution: 1/W2 = D22/D12; W1 = W2 × D22/D12 = 1.5 × 0.152/0.22 = 0.84 m/s. Answer: The flow velocity in the larger pipe is 0.84 m/s. 49. Solution: According to the relationship between head and rotational speed: H2/H1 = N2²/N1²; therefore, H2 = H1 × N2²/N1² = 20 × (2900/1450)² = 80 m. Answer: The head of this pump increases to 80 m. 50. Solution: Based on the given information: A1 = 200 × 0.5% = 1 ton; A2 = 1000 × 1% = 10 tons. B1 = 200 × 1% = 2 tons; B2 = 1000 × 1% = 10 tons. C2 = 1000 × 0.5% = 5 tons. Therefore, the amounts of additives A, B, and C that need to be added are as follows: A = A2 – A1 = 9 tons; B = B2 – B1 = 8 tons; C = 5 tons. The amount of base oil required is: 1000 – 200 – (9 + 8 + 5) = 778 tons. Answer: 9 tons of additive A, 8 tons of additive B, and 5 tons of additive C need to be added ； 778 tons of component oil are required.