The answers to Part 3 (True/False questions) of the technical expert examination for the mechanical equipment sector have been released
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1. When drawing a tolerance zone diagram, the upper deviation must be above the zero line, while the lower deviation must be below the zero line. ( ) 2. Parallelism is a type of positional tolerance. ( ) 3. In order to ensure that the end faces of the inner and outer rings of the bearing fit tightly against the shaft shoulder and the step in the bore of the bearing housing, the radius of curvature of those shaft shoulders and bore steps must be greater than the radius of curvature of the inner and outer circles of the bearing. ( ) 4.10 MPa = 10 kg/cm2 = 10×10^125 Pa. ( ) 5. The clearance between the spool and the valve bore, as well as the sealing elements, are important factors that determine whether a hydraulic system will leak or not. ( ) 6. Preheating before welding and maintaining heat after welding, along with slow cooling, are the main technical measures used when welding gray cast iron to prevent the formation of white cast iron and cracks. ( ) 7. Roots blowers and centrifugal blowers both belong to the category of rotary centrifugal blowers. ( ) 8. The axial thrust of a centrifugal compressor rotor is usually balanced by thrust bearings; there is then no need for additional balancing devices on the rotor. （ ） 9. When installing segmented tray plates, they are assembled sequentially from the center of the tower toward both sides of the tower wall. ( ) 10. When performing hot work on equipment, containers, and pipelines that have previously held flammable and explosive liquids, gases, and liquefied gases and have been left unused for many months, it is still necessary to carry out purging or cleaning. ( ) Answer: 1X 2√ 3X 4X 5√ 6√ 7X 8X 9X 10√ Note: As the grading is done by a single person, mistakes are inevitable; please understand! ! ! This post was last edited by zhangya*ong on 2009-4-1 13:08]
1. When drawing a tolerance zone diagram, the upper deviation must be above the zero line, while the lower deviation must be below the zero line. ( × ) 2. Parallelism is a type of positional tolerance. ( √ ) 3. In order to ensure that the end faces of the inner and outer rings of the bearing fit tightly against the shaft shoulder and the step in the bore of the bearing housing, the radius of curvature of those shaft shoulders and bore steps must be greater than the radius of curvature of the inner and outer circles of the bearing. ( × ) 4. 10 MPa = 10 kg/cm2 = 10 × 10^5 Pa. (× ) 5. The clearance between the spool and the valve bore, as well as the sealing elements, are important factors that determine whether a hydraulic system will leak or not. ( √ ) 6. Preheating before welding and holding the temperature after welding, along with slow cooling, are the main process measures used to prevent the formation of white cast and cracks when welding gray cast iron. ( √ ) 7. Both Roots blowers and centrifugal blowers belong to the category of rotary centrifugal blowers. ( × ) 8. The axial thrust of a centrifugal compressor rotor is usually balanced by thrust bearings; there is then no need for additional balancing devices on the rotor. ( × ) 9. When installing segmented tray plates, assemble them sequentially from the center of the tower toward both sides of the tower wall. ( √ ) 10. When performing hot work on equipment, containers, and pipelines that have previously held flammable and explosive liquids, gases, and liquefied gases and have been left unused for many months, it is still necessary to carry out purging or cleaning. ( √ ) Not sure if it’s correct? Last edited by Young Builder on 2009-3-28 12:34 ]
Correct=R; Incorrect=W 1. When drawing a tolerance zone diagram, the upper deviation must be above the zero line, and the lower deviation must be below the zero line. (W) When drawing tolerance zone diagrams, the upper tolerance is usually located above the zero line, while the lower tolerance is usually located below the zero line. 2. Parallelism belongs to positional tolerances (R). 3. In order to ensure that the end faces of the inner and outer rings of the bearing fit tightly against the shaft shoulder and the step in the bearing housing bore, the radius of curvature of those shaft shoulders and bearing housing bore steps must be greater than the radius of curvature of the inner and outer circles of the bearing. (W) 4.10 MPa = 10 kg/cm2 = 10 × 10^125 Pa; (W) 10 MPa = 100 kg/cm2 = 100 × 10^125 Pa. 5. The clearance between the spool and the valve bore, as well as the sealing elements, are important factors that determine whether a hydraulic system will leak or not. (R) 6. Preheating before welding and maintaining heat after welding, along with slow cooling, are the main technical measures used when welding gray cast iron to prevent the formation of white cast iron and cracks. (R) 7. Both Roots blowers and Darrieus blowers belong to the category of rotary centrifugal blowers. (W) 8. The axial thrust of a centrifugal compressor rotor is usually balanced by thrust bearings; there is then no need for additional balancing devices on the rotor. (W) 9. When installing segmented tray plates, assemble them sequentially from the center of the tower toward both sides of the tower wall. (W) 10. When performing hot work on equipment, containers, and pipelines that have previously held flammable and explosive liquids, gases, and liquefied gases and have been empty for many months, displacement or cleaning is still required. ( R )
× √ √ × √ √ × × √ √
1. When drawing a tolerance zone diagram, the upper deviation must be above the zero line, while the lower deviation must be below the zero line. ( × ) 2. Parallelism is a type of positional tolerance. ( √ ) 3. In order to ensure that the end faces of the inner and outer rings of the bearing fit tightly against the shaft shoulder and the step in the bore of the bearing housing, the radius of curvature of those shaft shoulders and bore steps must be greater than the radius of curvature of the inner and outer circles of the bearing. ( √ ) 4. 10 MPa = 10 kg/cm2 = 10 × 10^5 Pa (× ) 5. The clearance between the spool and the valve bore, as well as the sealing elements, are important factors that determine whether a hydraulic system will leak. ( √ ) 6. Preheating before welding and holding the temperature after welding, along with slow cooling, are the main process measures used to prevent the formation of white cast and cracks when welding gray cast iron. ( √ ) 7. Both Roots blowers and centrifugal blowers belong to the category of rotary centrifugal blowers. ( × ) 8. The axial thrust of a centrifugal compressor rotor is usually balanced by thrust bearings; there is then no need for additional balancing devices on the rotor. ( × ) 9. When installing segmented tray plates, assemble them sequentially from the center of the tower toward both sides of the tower wall. ( √ ) 10. When performing hot work on equipment, containers, and pipelines that have previously held flammable and explosive liquids, gases, and liquefied gases and have been left unused for many months, it is still necessary to carry out purging or cleaning. ( √ ) This post was last edited by yanglijuan on 2009-3-28 08:37 ]
1. When drawing a tolerance zone diagram, the upper deviation must be above the zero line, while the lower deviation must be below the zero line. (Wrong) 2. Parallelism is a type of positional tolerance. (Right) 3. In order to ensure that the end faces of the inner and outer rings of the bearing fit tightly against the shaft steps and the steps in the bearing housing bore, the radius of curvature of those shaft steps and bearing housing bore steps must be greater than the radius of curvature of the inner and outer circles of the bearing. (Incorrect) 4. 10 MPa = 10 kg/cm2 = 10 × 10^125 Pa (Incorrect) 5. The clearance between the spool and the valve bore, as well as the sealing elements, are important factors that determine whether a hydraulic system will leak. (Incorrect) 6. Preheating before welding and maintaining heat after welding, along with slow cooling, are the main process measures used to prevent the formation of white cast and cracks when welding gray cast iron. (Yes) 7. Roots blowers and vane blowers both belong to the category of rotary centrifugal blowers. (Incorrect) 8. The axial thrust on the rotor of a centrifugal compressor is usually balanced by thrust bearings; there is then no need for additional balancing devices on the rotor. (Incorrect) 9. When installing segmented tray plates, they are assembled sequentially from the center of the tower toward both sides of the tower wall. (Incorrect) 10. When performing hot work on equipment, containers, and pipelines that have previously held flammable and explosive liquids, gases, and liquefied gases and have been left unused for many months, it is still necessary to carry out purging or cleaning. ( Right )
1,4,7,8,9 Incorrect. Last edited by grjq on 2009-3-29 10:40]
1. When drawing a tolerance zone diagram, the upper deviation must be above the zero line, while the lower deviation must be below the zero line. (×) 2. Parallelism is a type of positional tolerance (√) 3. In order to ensure that the end faces of the inner and outer rings of the bearing fit tightly against the shaft shoulder and the step in the bore of the bearing housing, the radius of curvature of those shaft shoulders and bore steps must be greater than the radius of curvature of the inner and outer circles of the bearing. (×) 4.10 MPa = 10 kg/cm2 = 10×10^125 Pa (×) 5. The clearance between the spool and the valve bore, as well as the sealing elements, are important factors that determine whether a hydraulic system will leak or not. (√) 6. Preheating before welding and holding the temperature after welding, along with slow cooling, are the main technical measures used when welding gray cast iron to prevent the formation of white cast iron and cracks. (√) 7. Both Roots blowers and Dieterici blowers belong to the category of rotary centrifugal blowers. (×) 8. The axial thrust of a centrifugal compressor rotor is usually balanced by thrust bearings; there is then no need for additional balancing devices on the rotor. (×) 9. When installing segmented tray plates, assemble them sequentially from the center of the tower toward both sides of the tower wall. (×) 10. When performing hot work on equipment, containers, and pipelines that have previously held flammable and explosive liquids, gases, and liquefied gases and have been left unused for many months, replacement or cleaning is still required. (√)
There are a few things that aren’t entirely clear. 1. When drawing a tolerance zone diagram, the upper tolerance must be above the zero line, while the lower tolerance must be below the zero line. (Wrong) 2. Parallelism is a type of positional tolerance. (Right) 3. In order to ensure that the end faces of the inner and outer rings of the bearing fit tightly against the shaft steps and the steps in the bearing housing bore, the radius of curvature of those shaft steps and bearing housing bore steps must be greater than the radius of curvature of the inner and outer circles of the bearing. (Incorrect) 4. 10 MPa = 10 kg/cm2 = 10 × 10^125 Pa (Incorrect) 5. The clearance between the spool and the valve bore, as well as the sealing elements, are important factors that determine whether a hydraulic system will leak. (Incorrect) 6. Preheating before welding and maintaining heat after welding, along with slow cooling, are the main process measures used to prevent the formation of white cast and cracks when welding gray cast iron. (Yes) 7. Both Roots blowers and vane blowers belong to the category of rotary centrifugal blowers. (Incorrect) 8. The axial thrust on the rotor of a centrifugal compressor is usually balanced by thrust bearings; there is then no need for additional balancing devices on the rotor. (Incorrect) 9. When installing segmented tray plates, they are assembled sequentially from the center of the tower toward both sides of the tower wall. (Incorrect) 10. When performing hot work on equipment, containers, and pipelines that have previously held flammable and explosive liquids, gases, and liquefied gases and have been left unused for many months, it is still necessary to carry out purging or cleaning. ( Right )
1.× 2.√ 3.√ 4.× 5.√ 6.√ 7.× 8.× 9..× 10.√
1. When drawing a tolerance zone diagram, the upper deviation must be above the zero line, while the lower deviation must be below the zero line. ( Wrong ) 2. Parallelism is a type of positional tolerance (Correct). 3. In order to ensure that the end faces of the inner and outer rings of the bearing fit tightly against the shaft shoulder and the step in the bore of the bearing housing, the radius of curvature of those shaft shoulders and bore steps must be greater than the radius of curvature of the inner and outer circles of the bearing. (Incorrect) 4.10 MPa = 10 kg/cm2 = 10×10^125 Pa (Incorrect). 5. The clearance between the spool and the valve bore, as well as the sealing elements, are important factors that determine whether a hydraulic system will leak. (Incorrect) 6. Preheating before welding and maintaining heat after welding, along with slow cooling, are the main process measures used to prevent the formation of white cast and cracks when welding gray cast iron. (Yes) 7. Roots blowers and vane blowers both belong to the category of rotary centrifugal blowers. (Yes) 8. The axial thrust of a centrifugal compressor rotor is usually balanced by thrust bearings; there is then no need for additional balancing devices on the rotor. (Incorrect) 9. When installing segmented tray plates, they are assembled sequentially from the center of the tower toward both sides of the tower wall. (Incorrect) 10. When performing hot work on equipment, containers, and pipelines that have previously held flammable and explosive liquids, gases, and liquefied gases and have been left unused for many months, it is still necessary to carry out purging or cleaning. (Correct)
1. When drawing a tolerance zone diagram, the upper deviation must be above the zero line, while the lower deviation must be below the zero line. ( × ) 2. Parallelism is a type of positional tolerance (√). 3. In order to ensure that the end faces of the inner and outer rings of the bearing fit tightly against the shaft shoulder and the step in the bore of the bearing housing, the radius of curvature of those shaft shoulders and bore steps must be greater than the radius of curvature of the inner and outer circles of the bearing. (√) 4.10 MPa = 10 kg/cm2 = 10×10^125 Pa (×) 5. The clearance between the spool and the valve bore, as well as the sealing elements, are important factors that determine whether a hydraulic system will leak or not. (×) 6. Preheating before welding and maintaining heat after welding, along with slow cooling, are the main technical measures used when welding gray cast iron to prevent the formation of white cast iron and cracks. (√) 7. Roots blowers and Dieterici blowers both belong to the category of rotary centrifugal blowers. ( ×) 8. The axial thrust of a centrifugal compressor rotor is usually balanced by thrust bearings; there is then no need for additional balancing devices on the rotor. ( ×) 9. When installing segmented tray plates, assemble them sequentially from the center of the tower toward both sides of the tower wall. (×) 10. When performing hot work on equipment, containers, and pipelines that have previously held flammable and explosive liquids, gases, and liquefied gases and have been unused for many months, it is still necessary to carry out purging or cleaning. ( √) This post was last edited by rongdragon on 2009-3-28 12:27 ]
1X 2√ 3X 4X 5√ 6√ 7X 8X 9X 10√
1. When drawing a tolerance zone diagram, the upper deviation must be above the zero line, while the lower deviation must be below the zero line. ( x ) 2. Parallelism is a type of positional tolerance (√). 3. In order to ensure that the end faces of the inner and outer rings of the bearing fit tightly against the shaft shoulder and the step in the bore of the bearing housing, the radius of curvature of those shaft shoulders and bore steps must be greater than the radius of curvature of the inner and outer circles of the bearing. (x) 4.10 MPa = 10 kg/cm2 = 10 × 10^12 Pa. (x) 5. The clearance between the spool and the valve bore, as well as the sealing elements, are important factors that determine whether a hydraulic system will leak or not. (√) 6. Preheating before welding and maintaining heat after welding, along with slow cooling, are the main technical measures used when welding gray cast iron to prevent the formation of white cast iron and cracks. (√) 7. Roots blowers and centrifugal blowers both belong to the category of rotary centrifugal blowers. (x) 8. The axial thrust of a centrifugal compressor rotor is usually balanced by thrust bearings; there is then no need for additional balancing devices on the rotor. (√) 9. When installing segmented tray plates, they are assembled sequentially from the center of the tower toward both sides of the tower wall. (x) 10. When performing hot work on equipment, containers, and pipelines that have previously held flammable and explosive liquids, gases, and liquefied gases and have been left empty for many months, replacement or cleaning is still required. ( √ )
1.× 2.√ 3.× 4.× 5.√ 6.√ 7.× 8.× 9..× 10.√
1.× 2.√ 3.√ 4.× 5.√ 6.√ 7.× 8.× 9..× 10.√
1. When drawing a tolerance zone diagram, the upper deviation must be above the zero line, while the lower deviation must be below the zero line. (X) 2. Parallelism is a type of positional tolerance (√). 3. In order to ensure that the end faces of the inner and outer rings of the bearing fit tightly against the shaft shoulder and the step in the bore of the bearing housing, the radius of curvature of those shaft shoulders and bore steps must be greater than the radius of curvature of the inner and outer circles of the bearing. (X) 4.10 MPa = 10 kg/cm2 = 10×10^125 Pa. (X) 5. The clearance between the spool and the valve bore, as well as the sealing elements, are important factors that determine whether a hydraulic system will leak. (√) 6. Preheating before welding and holding the temperature after welding, along with slow cooling, are the main technical measures used when welding gray cast iron to prevent the formation of white cast iron and cracks. (√) 7. Both Roots blowers and vane blowers belong to the category of rotary centrifugal blowers. (X) 8. The axial thrust of a centrifugal compressor rotor is usually balanced by thrust bearings; there is then no need for additional balancing devices on the rotor. (X) 9. When installing segmented tray plates, assemble them sequentially from the center of the tower toward both sides of the tower wall. (X) 10. When performing hot work on equipment, containers, and pipelines that have previously held flammable and explosive liquids, gases, and liquefied gases and have been left unused for many months, replacement or cleaning is still required. (√)
1X 2√ 3X 4X 5√ 6√ 7X 8X 9X 10√ Additionally: Please provide the correct answers.
1. When drawing a tolerance zone diagram, the upper deviation must be above the zero line, while the lower deviation must be below the zero line. ( Wrong ) 2. Parallelism is a type of positional tolerance (Correct). 3. In order to ensure that the end faces of the inner and outer rings of the bearing fit tightly against the shaft shoulder and the step in the bore of the bearing housing, the radius of curvature of those shaft shoulders and bore steps must be greater than the radius of curvature of the inner and outer circles of the bearing. (True) 4.10 MPa = 10 kg/cm2 = 10×10^125 Pa (False) 5. The clearance between the spool and the valve bore, as well as the sealing elements, are important factors that determine whether a hydraulic system will leak. (Yes) 6. Preheating before welding and maintaining heat after welding, along with slow cooling, are the main technical measures used when welding gray cast iron to prevent the formation of white cast iron and cracks. (Yes) 7. Roots blowers and vane blowers both belong to the category of rotary centrifugal blowers. (Incorrect) 8. The axial thrust on the rotor of a centrifugal compressor is usually balanced by thrust bearings; there is then no need for additional balancing devices on the rotor. (Incorrect) 9. When installing segmented tray plates, they are assembled sequentially from the center of the tower toward both sides of the tower wall. (Incorrect) 10. When performing hot work on equipment, containers, and pipelines that have previously held flammable and explosive liquids, gases, and liquefied gases and have been left unused for many months, it is still necessary to carry out purging or cleaning. ( Right )
1. When drawing a tolerance zone diagram, the upper deviation must be above the zero line, while the lower deviation must be below the zero line. ( × ) 2. Parallelism is a type of positional tolerance. ( √ ) 3. In order to ensure that the end faces of the inner and outer rings of the bearing fit tightly against the shaft shoulder and the step in the bore of the bearing housing, the radius of curvature of those shaft shoulders and bore steps must be greater than the radius of curvature of the inner and outer circles of the bearing. ( × ) 4. 10 MPa = 10 kg/cm2 = 10 × 10^5 Pa. (× ) 5. The clearance between the spool and the valve bore, as well as the sealing elements, are important factors that determine whether a hydraulic system will leak or not. ( √ ) 6. Preheating before welding and holding the temperature after welding, along with slow cooling, are the main process measures used to prevent the formation of white cast and cracks when welding gray cast iron. ( √ ) 7. Both Roots blowers and centrifugal blowers belong to the category of rotary centrifugal blowers. ( × ) 8. The axial thrust of a centrifugal compressor rotor is usually balanced by thrust bearings; there is then no need for additional balancing devices on the rotor. ( × ) 9. When installing segmented tray plates, assemble them sequentially from the center of the tower toward both sides of the tower wall. ( √ ) 10. When performing hot work on equipment, containers, and pipelines that have previously held flammable and explosive liquids, gases, and liquefied gases and have been left unused for many months, it is still necessary to carry out purging or cleaning. ( √ )
When drawing a tolerance zone diagram, the upper deviation must be above the zero line, while the lower deviation must be below the zero line. ( × ) 2. Parallelism is a type of positional tolerance. ( √ ) 3. In order to ensure that the end faces of the inner and outer rings of the bearing fit tightly against the shaft shoulder and the step in the bore of the bearing housing, the radius of curvature of those shaft shoulders and bore steps must be greater than the radius of curvature of the inner and outer circles of the bearing. ( √ ) 4. 10 MPa = 10 kg/cm2 = 10 × 10^5 Pa (× ) 5. The clearance between the spool and the valve bore, as well as the sealing elements, are important factors that determine whether a hydraulic system will leak. ( √ ) 6. Preheating before welding and holding the temperature after welding, along with slow cooling, are the main process measures used to prevent the formation of white cast and cracks when welding gray cast iron. (√) 7. Roots blowers and vane blowers both belong to the category of rotary centrifugal blowers. ( × ) 8. The axial thrust of a centrifugal compressor rotor is usually balanced by thrust bearings; there is then no need for additional balancing devices on the rotor. ( × ) 9. When installing segmented tray plates, assemble them sequentially from the center of the tower toward both sides of the tower wall. ( √ ) 10. When performing hot work on equipment, containers, and pipelines that have previously held flammable and explosive liquids, gases, and liquefied gases and have been left unused for many months, it is still necessary to carry out purging or cleaning. ( √ ) This post was last edited by fdsunset on 2009-3-30 15:53 ]