Advanced Chemical Compressor Operator Exam Paper

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Test Paper for Senior Chemical Compressor Technicians I. True or False Questions (Mark “√” in the brackets for correct answers and “×” for incorrect ones. 2 points per question, totaling 120 points) 1. A static load is one in which the load increases suddenly, its magnitude and direction change over time, or it is an impact-type load; such a load is considered a static load. ( ) Answer: × 2. Dynamic load is a load whose magnitude and direction remain unchanged or change only slightly after a certain value of load is applied; such a load is considered a dynamic load. ( ) Answer: × 3. The main cause of fracture is low-stress fracture. ( ) Answer: √ 4. The cause of crankshaft fracture is the occurrence of original cracks. ( ) Answer: √ 5. The basic form of a hinge-four-bar mechanism is the multi-rocker mechanism. ( ) Answer: × 6. The basic forms of hinge four-bar mechanisms include the three-crank mechanism. ( ) Answer: × 7. The basic forms of hinge four-bar mechanisms are crank-rocker mechanisms. ( ) Answer: √ 8. The guide rod mechanism evolved from the crank mechanism by using different rods as the frame. ( ) Answer: × 9. The crank-slider mechanism evolved from the crank-rocker mechanism. ( ) Answer: √ 10. The critical speed is the speed at which, when the compressor rotor is rotating, the vibration frequency generated by it becomes equal to the rotor’s natural frequency, and this corresponds to the speed of the compressor’s main shaft. ( ) Answer: √ 11. The economic indicators for compressors are specific volume energy and specific weight. ( ) Answer: √ 12. The three aspects of compressors refer to: systematization, creditization, and standardization. ( ) Answer: × 13. An adiabatic change process refers to a compression process in which the heat content within the cylinder remains constant; this is an adiabatic compression process. ( ) Answer: × 14. Isothermal compression process: This refers to a compression process in which the temperature of the gas remains constant; it is thus an isothermal compression process. ( ) Answer: √ 15. A thermodynamic process refers to the course in which the gas within a system undergoes changes in state according to certain laws, as influenced by external forces; this is what constitutes a thermodynamic process. ( ) Answer: √ 16. Similarly, in deep-sea submersibles and counterweight devices, light metals are often used for manufacturing in order to increase their weight and thus enhance stability. ( ) Answer: × 17. In actual production, such as in the manufacturing of airplanes and satellites, in order to reduce weight and save fuel, heavy metals with high density but low strength are often used. ( ) Answer: × 18. An angular compressor is a type of compressor in which the centerlines of its cylinders are at a certain angle to one another, but this angle is not 180°; such compressors are referred to as angular compressors. ( ) Answer: √ 19. A turbine compressor relies on the high-speed rotation of impellers to increase the pressure and velocity of the gas; subsequently, within fixed components, part of this velocity is further converted into pressure energy of the gas – such a compressor is known as a turbine compressor. ( ) Answer: √ 20. A positive-displacement compressor is a type of compressor in which pistons move back and forth or rotate inside cylinders, thereby reducing the volume of the gas and increasing its pressure. It is called a positive-displacement compressor. ( ) Answer: √ 21. A piston compressor is a type of compressor in which a crank-slider mechanism is used to convert the rotational motion of the drive unit into the reciprocating motion of the piston. The piston and the cylinder together form the compression volume, and it is through the reciprocating motion of the piston that the processes of intake, compression, and exhaust take place in this type of compressor. ( ) Answer: √ 22. A vertical compressor is one in which the cylinder and the foundation are arranged horizontally, and the piston also moves back and forth horizontally; such a compressor is known as a vertical compressor. ( ) Answer: × 23. A horizontal compressor is one in which the cylinder and the foundation are arranged vertically, and the piston moves up and down vertically; this is what constitutes a horizontal compressor. ( ) Answer: × 24. The volume occupied by 1 kg of gas is the specific volume of that gas. ( ) Answer: √ 25. The amount of impurities present in a certain volume of gas determines the purity of that gas. ( ) Answer: × 26. Air purification involves removing moisture, oil, and impurities from the air that is to be compressed, thereby making the air pure. ( ) Answer: √ 27. A polytropic compression process is one in which the compression does not occur under completely constant pressure nor at completely constant temperature; it is therefore a polytropic compression process. ( ) Answer: × 28. The ratio of the compressor’s final exhaust pressure to its inlet suction pressure is known as the pressure ratio. ( ) Answer: √ 29. For blanks that are large in size and important, casting is generally used. ( ) Answer: × 30.> The common materials for the piston rings in oil-lubricated compressors are gray cast iron or alloy cast iron. ( ) Answer: √ 31. For the piston rings of compressors that use low-oil lubrication, the common materials are nylon ropes and pure wood. ( ) Answer: × 32. > For the piston rings of oil-free lubrication compressors, the commonly used material is filled polytetrafluoroethylene. ( ) Answer: √ 33. There are two types of material deformation: one is spring deformation, and the other is plastic deformation. ( ) Answer: × 34. A force diagram is one in which the object under study is separated from the surrounding objects; it shows a simple outline of that object alone, along with an indication of all the forces acting on it. Such a diagram is known as a force diagram. ( ) Answer: × 35. The ideal gas law states that for a given mass of ideal gas, the product of its pressure (P) and volume (V) is equal to the ratio of this product to the thermodynamic temperature (T); this value changes as the state of the gas changes. That is: P = PV/T = variable. ( ) Answer: × 36. An intermittent mechanism is a device in which, when the driving element moves continuously, the driven element performs periodic intermittent movements; such a device is thus an intermittent mechanism. ( ) Answer: √ 37. The shaft power of a compressor is the actual power transmitted by the drive mechanism to the compressor’s crankshaft; this is what constitutes the compressor’s shaft power. ( ) Answer: √ 38. Mechanical efficiency refers to the fact that when a machine is in operation, frictional forces cause some power to be wasted, as a result of which the input power cannot be fully utilized. Mechanical efficiency is used to measure the degree to which the input power of a machine is actually utilized. ( ) Answer: √ 39. Indicative efficiency refers to the ratio of theoretical power to indicative power; that is, it is the indicative efficiency. ( ) Answer: √ 40. Indicated power refers to the work consumed in one theoretical cycle per unit of time by a piston compressor; this is what is meant by indicated power. ( ) Answer: × 41. The specific power refers to the work consumed in the actual cycle by the compressor per unit of time; that is, it is the specific power. ( ) Answer: √ 42. The quality standards for compressors specify four grades: A, B, C, and D. ( ) Answer: × 43. > Important features ； It refers to a characteristic that, although not a critical one, may, in the event of certain issues, prevent the final product from being completed or fulfilling its intended purpose; such a characteristic is then considered critical. ( ) Answer: × 44. The methods for drying compressed air include chemical methods, adsorption methods, freezing methods, and pressure dehumidification methods. ( ) Answer: × 45. > General characteristics: Although this characteristic is closely related to product quality, in most cases it does not affect the performance of the product. ( ) Answer: × 46. The theoretical compression process refers to an idealized compression process in which it is assumed that the conditions of the gas remain unchanged during inhalation, there is no clearance inside the cylinder, no energy loss occurs during compression, and no leakage takes place; furthermore, the state of the gas remains unchanged during the exhaust process. This is what constitutes the theoretical compression process. ( ) Answer: √ 47. Critical characteristics refer to those properties that, in the event of an accident, could pose a threat to human safety or lead to the failure of the product system or its inability to fulfill its intended functions; such properties are known as critical characteristics. ( ) Answer: × 48. An automatic control relay has many functions, including knife switches, fuses, thermal relays, and voltage loss protection. ( ) Answer: √ 49. A thermal relay is used for overload protection, and its contacts operate under the control of temperature. ( ) Answer: √ 50. The main contacts are usually normally open, while the auxiliary contacts can also be normally open or normally closed. ( ) Answer: √ 51. > A contactor is a common type of electrical device, and its auxiliary contacts are used to control the current flow. ( ) Answer: × 52.> Contactors are one of the most common electrical devices; their main contacts are used to control the main motor. ( ) Answer: × 53. Indication efficiency is the comparison between the theoretical efficiency and the indicated power; it represents the indication efficiency. ( ) Answer: √ 54. Indicated power is the work done by a piston compressor per unit volume during an actual cycle; it is thus known as indicated power. ( ) Answer: × 55. The shaft power rate refers to the power consumed by the compressor in a unit amount of time for one theoretical cycle; it is essentially the power rate. ( ) Answer: × 56. The specific volume energy refers to the ratio of the actual shaft power consumed by the compressor under specified operating conditions to its displacement. ( ) Answer: √ 57. Electric shock is an external injury to the human body. ( ) Answer: √ 58. Electric injury is an internal injury to the human body. ( ) Answer: √ 59. Specific heat refers to the amount of heat absorbed or released per unit mass of a substance when its temperature increases or decreases by 1°C; this is what constitutes the specific heat of that substance. ( ) Answer: × 60. The piston stroke refers to the distance that the piston travels within the cylinder, from one end to the other or from the outside to the inside; this is what is known as the stroke. ( ) Answer: √ II. Multiple-choice questions (Please fill in the code of the correct answer in the brackets; 2 points for each question, totaling 120 points) 1. The use, maintenance, and repair of containers such as gas storage tanks and cylinders shall comply with ( ) the “Technical Specifications for Welded Steel Containers” as well as the relevant provisions in the “Safety Supervision Regulations for Pressure Vessels” issued by the Ministry of Labor. A. JB-741-80 B. JB-741-81 C. JB-741-82 D. JB741-83 Answer: A 2. Among centrifugal, piston, vane, and screw compressors, which type requires the most maintenance? A. Centrifugal B. Piston C. Vane D. Screw Answer: B 3. A compressor with a compression ratio of ( ) that compresses gas in multiple stages is called a multi-stage compressor A. 51–700 B. 51–800 C. 51–900 D. 51–1000 Answer: D 4. A compressor that compresses gas twice with a compression ratio of ( ) is a double-acting compressor. A. 9–30 B. 9–40 C. 9–50 D. 9–60 Answer: C 5. A compressor that compresses gas in one stroke with a compression ratio of ( ) is a single-stage compressor. A. 2－4 B. 2－6 C. 2－8 D. 2－10 Answer: C 6. The basic requirements for the safe operation of mechanical components are: ① Sufficient strength ； ②It has sufficient stiffness and ( ). A. Voltage stability B. Stability C. Resistance to stress D. Solidity Answer: B 7. The volumetric flow rate of the compressor is not less than ( )% of the nominal value. A. 65 B. 75 C. 85 D. 95 Answer: D 8. The aviation lubricant that can be used as a substitute for HS-19 compressor oil is ( ). A. HJ-30 B. HC-14 C. HH-20 D. HL-18 Answer: C 9. The bolts in a bolt group connection should be arranged with a reasonable ( ) clearance to allow space for wrenches. A. Inter-solidity B. Inter-hardness C. Spacing D. Inter-solidity Answer: C 10. When arranging bolts in a bolted connection, it should be convenient for the bolts to be ( ) reasonably. A. Under compression B. Under squeezing C. Under load D. Subject to force Answer: D 11. In bolt group connections, multiple bolts are generally arranged according to the geometric principle of the axis ( ). A. Symmetric B. Asymmetric C. Aligned D. Offset Answer: A 12. The connecting rod drives the slider to move back and forth in a straight line; the length of the slider’s travel is equal to ( ) times the length of the curved plate. Conversely, the slider can also act as the driving element. A. 1 B. 2 C. 3 D. 4 Answer: B 13. The crosshead is used to connect the piston and ( ) and to transmit pressure from the connecting rod to the piston rod. A. Piston rod B. Piston ring C. Piston pin D. Piston seal Answer: A 14. A tight key connection relies on the ( ) sides of the key to function. A. Up and down B. Left and right C. Front and back D. Both sides Answer: A 15. A loose-key connection operates based on the ( ) of the chain. A. Two end faces B. Two large faces C. Two small faces D. Two side faces Answer: D 16. The torsion spring comparator should be installed on a fixed bracket; before use, its height should be adjusted so that the probe of the torsion spring comparator can descend slowly towards the gauge block or workpiece, moving gently ( ). A. Joining B. Approaching C. Connecting properly D. Making contact Answer: D 17. When using a measuring instrument to measure a workpiece, the axis of the measuring rod must be perpendicular to the part being measured ( ). A. Epidermis B. Epispheroid C. Epizone D. Surface Answer: D 18. Product quality can be summarized as the suitability of a product, and it is used to measure the extent to which it meets users’ requirements during its use. A. Satisfied B. Content C. Very good D. Perfect. Answer: B. 19. An automatic air circuit breaker has many functions; it includes a knife switch, a fuse, a thermal relay, and ( ). A. Pressure loss protection B. Failure protection C. Drift protection D. Loss of control protection Answer: A 20. The basic control elements in a relay contactor control circuit include the jogging element, the feeding element, and the feed-back element ( ) ( ). A. Protection of cycles B. Protection of regulation C. Protection of details D. Protection of periods Answer: A 21. When the >4L‑20/8 type compressor is in operation, it is necessary to ensure that ( ) is in good working condition. A. Oil injection gun B. Oil injector C. Oil injection cylinder D. Oil pouring pot Answer: B 22. The penetration value is an indicator for ZFG‑1 composite calcium-based grease. A. 310–320 B. 310–330 C. 310–340 D. 310–350 Answer: C 23. After repairing the compressor cylinder, the test pressure for the water chamber is ( ) MPa. A. 0.1 B. 0.2 C. 0.3 D. 0.4 Answer: C 24. After repairing the compressor cylinder, the test pressure of the gas chamber should be ( ) times the maximum operating pressure. A. 1.3 B. 1.5 C. 1.7 D. 1.9 Answer: B 25. The basic forms of the diagram of a hinge four-bar mechanism include ( ) mechanisms. A. Dual joystick B. Single joystick C. Triple joystick D. Multiple joysticks Answer: A 26. The basic forms of hinge four-bar mechanisms include ( ) mechanisms. A. Double crank B. Single crank C. Triple crank D. Multiple cranks Answer: A 27. The basic forms of the link mechanisms in a hinge four-bar mechanism include ( ) cross-bar mechanism diagrams. A. Crankshaft B. Crank arm C. Crank D. Rod Answer: C 28. The drying methods for compressors include: ① Chemical method ； ②Adsorption method ； ③Freezing method and ( ). A. Dehumidification method B. Degassing method C. Deicing method D. Moisture removal method Answer: D 29. The severity of electric shock injuries is related to the magnitude and frequency of the current flowing through the body, the path taken by the current, the length of ( ), as well as the physical condition of the person who is shocked. A. Hours and seconds B. Time of day C. Hours and minutes D. Time Answer: D 30. When the mass of a piston ring decreases by ( ) due to wear, it needs to be replaced. A. 0.5% B. 10% C. 15% D. 20% Answer: B 31. The piston ring needs to be replaced when its thickness exceeds ( ) mm. A. 0.6～1.6 B. 0.8～1.8 C. 1.0～2.0 D. 1.2～2.2 Answer: C 32. Fans and blowers are mainly used to convey ( ). A. Oxygen B. Gases C. Air D. Hydrogen Answer: B 33. Ventilation machinery can be divided into three main categories: ventilators, blowers, and ( ). A. Press B. Die-casting machine C. Pressing machine D. Compressor Answer: D 34. When two centrifugal compressors of identical model are connected in parallel in a network, the total exhaust volume is not equal to the sum of the exhaust volumes of the two machines; rather, the total exhaust volume ( ) the sum of the exhaust volumes of each individual machine. A. Less than B. Equal to C. Greater than D. Close to Answer: A 35. The secondary maintenance of the 4L–20/8 type compressor is carried out by specialized ( ) workers. A. Inspection B. Examination C. Maintenance D. Calibration Answer: C 36. The rod bolts of the 4L-20/8 type compressor need to be replaced after working for ( ) nh. A. 9000000 B. 8000000 C. 7000000 D. 6000000 Answer: A 37. The connecting rod of a 4L‑20/8 type compressor needs to be replaced after working for ( ) nh. A. 22000000 B. 23000000 C. 24000000 D. 25000000 Answer: D 38. The compressor needs to have its bearings and oil circuits disassembled, cleaned, and maintained after every ( ) hours of operation. A. 2000–3000 B. 3000–4000 C. 4000–5000 D. 5000–6000 Answer: C 39. After the compressor has been operating for ( ) hours, it is necessary to adjust the clearance between the shaft bearings and the crankshaft neck. A. 600–650 B. 700–750 C. 800–850 D. 900–950 Answer: B 40. A machine used to compress and transport ( ) and various other gases is called a gas compressor. A. Moisture B. Atmosphere C. Humidity D. Steam Answer: B 41. The purpose of steel quenching is to increase the hardness of steel and ( ). A. Heat resistance B. Acid resistance C. Alkali resistance D. Wear resistance Answer: D 42. The grade of high-quality tool steel is T8A. A. T10A. ( ). A. T12A B. T14A C. T16A D. T18A Answer: A 43. The ferritic stainless steel grade is 1Cr17, ( ). A. 2Cr17 B. 3Cr17 C. 1Cr18Ti D. 1Cr19Ti Answer: D 44. If the tight fit between the outer surface of the piston ring and the cylinder wall is no longer maintained, and the total clearance exceeds ( ) of the cylinder’s circumference, then the piston ring should be replaced. A. 30% B. 40% C. 50% D. 60% Answer: C 45. The specific heat at constant volume refers to the amount of heat absorbed by a unit amount of gas when its temperature rises by ( )℃, with the volume remaining constant; this value is known as the specific heat at constant volume. A. 0.6 B. 0.8 C. 1.0 D. 1.2 Answer: C 46. The specific heat at constant pressure refers to the amount of heat absorbed by a unit amount of gas when its temperature increases by ( )℃ under constant pressure; this is what is known as specific heat at constant volume. A. 1 B. 2 C. 3 D. 4 Answer: A 47. The contents of team-level accounting should be based on the actual production conditions of each team; it is necessary to account for what is actually done, without imposing uniform standards. There should not be too many accounting indicators – it is important to ( ). A. Simple and feasible B. Concise with multiple lines C. Concise and easy to implement D. Concise with few lines Answer: C 48. The main supporting equipment for the >4L-20/8 type compressor is ( ), with the model number WGO‑600 and a capacity of 1.5 cm3. A. Gas distribution tank B. Gas distribution cylinder C. Gas distribution bottle D. Gas distribution cylinder. Answer: D. 49. What is the purpose of the secondary cooler, which is one of the main auxiliary equipment for the >4L-20/8 type compressor? A. Cooling air B. Cooling compressed air C. Cooling humid air D. Cooling dry air Answer: B 50. The main auxiliary equipment for the >4L-20/8 type compressor is the circulation water pump; the brand of this pump is 2F-40 and ( ). A. 2BA-10 B. 2BA-8 C. 2BA-6 D. 2BA-4 Answer: C 51. The capacity of the air storage tank, which is the main auxiliary equipment for the >4L-20/8 type compressor, is ( ) m3. A. 2.0 B. 2.5 C. 3.0 D. 3.5 Answer: B 52. The model number of the electrical control box for the main auxiliary equipment of the 4L-20/8 type compressor is: ( ). A. PV(N)6101 B. PV(N)6102 C. PV(N)6103 D. PV(N)6104 Answer: A 53. Commonly used adsorbents include silica gel, activated carbon, and ( ). A. Molecular valve B. Molecular pad C. Molecular pore D. Molecular sieve Answer: D 54. Cracks and leaks in cylinder water pumps can be repaired using five methods: stitching with nails, applying patches, ( ) floating putty, and cold welding. A. Metal spraying B. Metal bonding C. Metal extrusion D. Metal riveting Answer: A 55. >Friction-based anti-loosening: such as double nuts ( ). A. Ball washer B. Spring washer C. Elastic washer D. Tubular washer Answer: B 56. Mechanical anti-loosening methods include stop washers, slotted nuts and cotter pins ( ) round nuts and lock washers, etc. A. Wires made of copper B. Wires made of aluminum C. Wires made of steel D. Wires made of metal Answer: D 57. Common anti-loosening measures include: ① Anti-loosening through friction ； ②( ) Anti-loosening. A. Mechanical anti-loosening B. Mechanical-driven anti-loosening C. Frictional anti-loosening D. Electric anti-loosening Answer: A 58. Under the effects of impact, vibration, variable loads, or significant temperature changes, a threaded connection may ( ). A. Loosen B. Relax C. Loosen up D. Tightness Answer: C 59. Among centrifugal, piston, vane, rod, and diaphragm compressors, which one has the highest efficiency? ( ) compressor. A. Sliding vane type B. Diaphragm type C. Linkage type D. Piston type Answer: D 60. The area where the piston comes into contact with the packing should be treated using ( ) heat treatment method. A. Tempering B. Annealing C. Quenching D. Normalizing Answer: C III. Calculation questions (10 points per question, 50 points in total) 1. It is known that the net weight of a certain part is 440 g. The material consumption for the parts is 93.8 g. What is the material utilization rate? Answer: Solution: The material utilization rate for this part is Answer: The material utilization rate of this part is 46.9%. 2.>A 1000-watt incandescent lamp powered by a 220V single-phase supply, with a cable length of 500 meters and insulated copper wires; a voltage drop of 3% is allowed in the circuit. What is the minimum cross-sectional area of the wires required? (Problem statement: Conductivity of copper wire: γ=54 m/WΩ) Answer: Solution: According to the formula, the minimum cross-sectional area of the wire is 16 mm2. 3.>There is a civil pipeline requiring a flow rate of 150 m3/h. What is the appropriate diameter for this pipeline? (Economic flow rate W = 1.5 m3/s) Answer: Solution: According to the formula, the appropriate pipe diameter is 188 mm. 4.>There is a single-rod piston cylinder with a piston diameter of 800 mm and a piston rod length of 4 cm. If the reciprocating speed of the piston rod is required to be 0.5 m/s, what is the flow rate of oil entering the rodless chamber of the cylinder? Answer: Solution: In the rodless chamber, Q = V × A. Q = 0.5 × 3.1416 × 82/4 = 250×10⁻⁴ m³/h. Answer: The volume of oil flowing into the cylinder in the rodless chamber is 250×10⁻⁴ m³/h. 5.>In a steam pipe with a diameter of 159×6, the average flow velocity of the steam is 26 m3/s; the volumetric flow rate of steam in this pipe is 1587.7 m3/h. What is its mass flow rate? (Vapor density P=2.62) Answer: Solution: The mass flow rate formula is G=ρ•V•S(P•Q). Therefore, G=2.62×1587.7, which gives G=4160 kg/h. Answer: The mass flow rate of vapor per hour is 4160 kg/h. IV. Short-answer questions (5 points per question, 50 points in total) 1. >What are the steps in fixture design? Answer: ①Master the necessary design materials ； ②Conduct workpiece process analysis ； ③Based on production realities, formulate a fixture structure plan and draw design sketches ； ④Draw the fixture assembly diagram ； ⑤Determine the design requirements for the fixture and the drawings of its components ； ⑥Proofreading, reviewing, approving, tracing, etc. 2.>What is process performance? What does it include in total? Answer: Processability refers to the ability of metal materials to adapt under specified cold and hot processing conditions during the machining of mechanical parts or the manufacturing of tools. The processing properties of metals include: casting properties, forgeability, weldability, and machinability, among others. 3.>What are the steps for preparing a process procedure? Answer: ① Process analysis of the part drawing ； ②Determine the type of blank ； ③Prepare the process route ； ④Determine the equipment, fixtures, cutting tools, measuring instruments, and auxiliary tools required for each process ； ⑤Determine the machining allowances and dimensional tolerances between various processes ； ⑥Determine cutting parameters and man-hour quotas ； ⑦Fill in the process procedure. 4.> What is the basis for preparing the process specifications? Answer: The following specifications must be followed when preparing the process procedures: ① Product design documents ； ②Production conditions ； ③Technological methods ； ④Overall process plan ； ⑤Regarding technical standards. 5.> What are the contents of team economic accounting? Answer: The main aspects of economic accounting at the team level include: it is necessary to base the accounting on the actual production activities of the team, to account for whatever is actually done, without imposing uniform standards; there should not be too many accounting requirements, as they need to be simple and easy to implement. 6.>What are the eight economic indicators for enterprises? Answer: The eight economic indicators for enterprises are: ① Product output ； ②Product variety ； ③Product quality ； ④Primary raw materials, fuel, and power consumption ； ⑤Labor productivity ； ⑥Product cost ； ⑦Working capital ； ⑧Profit. 7.>What is product quality, and how can the quality of compressed air be assessed? Answer: The quality of a product is summarized as its suitability, which is used to measure the extent to which it meets users’ requirements during use. The purified compressed air discharged at the end of compression must be tested to determine whether it meets the process requirements. ①The purified air discharged from the compressor is vented using standard methods, after which the presence of oil, water, or other impurities and contaminants in the air is inspected visually; compressed air that is clean and free from such substances is considered qualified. ②A sample of purified air is taken for chemical testing to determine whether there is oil, water, or other impurities present. 8.>Briefly describe the working principle of a vertical single-cylinder single-acting reciprocating compressor? Answer: Vertical single-acting single-cylinder reciprocating compressor. As the piston moves from the top dead center to the bottom dead center, the volume of the cylinder increases; the compressed air in the clearance expands, causing the pressure inside the cylinder to drop. When this pressure falls below atmospheric pressure, the intake valve is pushed open, and fresh air passes through the air filter and enters the cylinder via the intake valve, until the piston reaches the bottom dead center. As the piston moves upward, the intake valve closes, and the gas inside the cylinder is compressed by the piston, causing the pressure to rise. Once this pressure exceeds that in the air storage tank, the process continues until the piston reaches its top dead center. This cycle repeats over and over again, with fresh air being continuously drawn into the compressor, compressed, and then stored in the air storage tank. 9.> Why is a clearance needed in the cylinder of a piston compressor? Answer: The reason is: ① When compressed air is compressed, there is some water vapor in it; once this vapor condenses, water is incompressible, and if there is no space left, there is a risk of collision. ②The presence of clearance and the expansion of air within that clearance allow the intake valve to open and close more smoothly. ③Having some clearance prevents the piston from colliding with the cylinder. ④There is a gap to mitigate the impact of air on intake and exhaust. ⑤For the purposes of assembly and adjustment, a certain gap is also required between the cylinder head and the piston end face at the dead center position. 10.> What regulations should be followed regarding the use, maintenance, and repair of containers such as air tanks and air cylinders used in compressors? Answer: It shall comply with JB•741－80 \"Technical Requirements for Welded Steel Pressure Vessels\" and the relevant provisions in the \"Regulations on the Safety Supervision of Pressure Vessels\" issued by the General Administration of Labor.