1. What is the pump? A: the pump is the prime mover's mechanical energy into a mechanical pumping liquid energy.
2. What is power? A: the work done, per unit time is called power.
3. What is the effective power? Removal of mechanical energy loss and consumption, liquid through the pump to get the actual power per unit time, is called the effective power.
4. What is the shaft power? A: the power of the motor to the pump shaft, called the shaft power
5. Why do you say to the pump motor power is always greater than the effective power of the pump? Answer: 1) the centrifugal pump in operation, the part of the pump with high pressure liquid to flow back to the entrance of the pump, even outside the pump leakage, so it must be part of the energy loss; 2). When the liquid flows through the impeller and the pump shell, the change of flow direction and speed, as well as the mutual impact between the fluid and so on are also part of the energy consumption; 3). The pump shaft and the mechanical friction between the bearing and shaft seal part of energy consumption; Therefore, the motor to shaft power is always greater than the effective power.
6. What is the total efficiency of the pump? A: the effective power of the pump and the ratio of the shaft power, is the overall efficiency of the pump.
7. What is the pump flow? Use what symbol? Flow is refers to the unit time through the pipe a section of the amount of liquid volume (or quality). Pump flow expressed in "Q".
8. What is the pump lift? Use what symbol? A: the head is refers to the unit weight of fluid energy gained by the increment. Pump lift expressed in "H".
9. What is the distinguishing feature of chemical pump? Answer: 1.) can meet the requirements for chemical process; 2). The corrosion resistance; 3). The high temperature resistant, low temperature; 4) wear-resisting, scouring resistance; 5) reliable operation; 6) no leak or leak less; 7) can be critical state of liquid. 8) has good cavitation performance
10. The commonly used mechanical pump according to the principle of work is divided into several categories? Answer: 1) the vane pump. Through the pump shaft rotates to drive all kinds of impeller blades to liquid with centrifugal or axial force, conveying liquid to a pipe or container, such as centrifugal pump, vortex pump, mixed flow pump, axial flow pump. 2) positive displacement pump. Using the pump cylinder volume content of the product the continuous change of conveying liquid pump, reciprocating pump, piston pump, gear pump, screw pump; 3) other types of pumps. Such as the use of electromagnetic transmission liquid electric conductor electromagnetic pump; Using the fluid energy to transport a liquid pump, such as injection pump or air lift device
What should be done before 11. Chemical pump repair process? Answer: 1) must stop before machinery, equipment maintenance, temperature, pressure, cut off power supply; 2) there are flammable, explosive, toxic, corrosive medium of machinery, equipment, maintenance must be carried out before cleaning, neutralization, displacement analysis detection qualified rear can construction; 3) maintenance of inflammable, explosive, poisonous, corrosive medium or steam equipment, machinery, piping, must cut off material, inlet valve, and added a blind flange.
Before 12. Chemical pump maintenance should have what conditions? Answer: 1) stop, 2) cool; 3) pressure; 4) to cut off the power supply; 5) replacement
13. General mechanical removal principle is what? A: under normal circumstances should be outside, after, after the first remove, in turn for integral parts as far as possible the overall disassembly.
14. In the centrifugal pump power loss by what? Answer: there are three kinds of loss: hydraulic loss, volumetric loss, mechanical loss. 1) hydraulic loss: in the pump body of fluid flow, if the flow is smooth, the resistance is small, rough passage, resistance and larger water into the rotation of the impeller or water flow out of the impeller also caused by collision and the vortex loss is produced. Above two kinds of loss is called the hydraulic loss. 2) volume loss: the impeller is rotating, and pump body is a static fluid in a small gap between the impeller and the pump body back into the impeller of the imported; In addition, some fluid from balance hole back into the impeller imports, or from the shaft seal leakage. If it is a multistage pump, from part of balance disc to leakage. These losses, volume loss; 3) mechanical loss: shaft and bearing in turns to, filler, such as friction, impeller in the pump body, impeller cover plate to fluid friction, before and after are part of the power consumption, which caused by mechanical friction loss, always become mechanical loss.
15. In production practice, the rotor to find balance according to what is it? Answer: according to the different revolutions and structure, can choose static balance method or dynamic balance method. The rotator can use static balance method to solve the static balance. Static balance can balance of revolving centre of gravity of imbalance (that is, to eliminate torque), not eliminate the imbalance of couple. So the static balance generally applies only to the relatively small diameter disc of revolving body. For diameter larger body of revolution, dynamic balancing problems tend to be more common and prominent, so want to deal with dynamic balancing.
16. What is the balance? Balance points a few class? Answer: 1) eliminate the unbalanced rotating parts or components of work called balance; 2) balance can be divided into two kinds of dynamic balance and static balance.
17. What is the static balance? A: where there are some special tooling, do not need to rotate under the status of the front of the determination of imbalances in the rotating parts, at the same time, should add the size and location of the unbalanced force can be determined, this find balance method is called static balance.
What is a dynamic balance.? A: every part rotates in parts, not only should focuses on balance the centrifugal force generated by the, but also the balance of the balance of centrifugal force moment of couple called dynamic balance. Dynamic balance is commonly used in high speed, large diameter, work precision machine parts of special strict, must do the precise dynamic balance.
19. Do static balancing of rotating parts, focuses on to balance parts to determine the location? A: first of all to be balance on the balance tooling free rolling several times, if the last time is clockwise, the parts must be located in the right side of the vertical centerline of centre of gravity of frictional resistance for the (relationship), at this point in the bottom of the parts, made a white chalk marks, and then let the parts free rolling, final rolling pendulum is finished in a counterclockwise direction, the focus must be balanced parts is located in the left of the vertical centerline, also make a mark in white chalk, then record the weight of the two is lay particular stress on bearing.
20. A static balancing of rotating parts, how to determine the size of the balance weight? A: first of all the parts of the bearing to the horizontal position of lay particular stress on, and on the other side of symmetric position at the great circle point with appropriate optimal weight. To this point should be considered when choose a suitable heavy parts, whether for weight and weight loss in the future, and after the optimum weight plus, remain horizontal position or slight swing, turn 180 degrees, then the parts to keep its level, repeated several times, after the optimum weight to determine the same,'ll take out the optimal weight according to weight, that determine the size of counterbalance gravity.
21. The types of mechanical rotor imbalance have? A: the static and dynamic imbalance imbalance and mixed imbalance.
22. The pump shaft bending how to make the measurement? Answer: the bending axis, will cause the imbalance of the rotor and action of wear and tear, small bearings on the v-shaped iron, large bearing on the wheel bracket, v-shaped iron or support to put a solid, again dial gauge get on table dry point to axis, and then slowly plate of pump shaft, such as bending, each round micrometer has a maximum and minimum of readings, the difference between the two readings show the maximum radial runout of the shaft, also known as degree. Half of the shaft bending is shaking degree, among axial radial runout is generally not more than 0.05 mm, both ends of more than 0.02 mm.
23. The mechanical vibration reason is roughly summarized as three categories? Answer: 1) structure: design flaws have manufacturing; 2) installation of: mainly caused by improper assembly and maintenance assembly; 3) run: due to the improper operation, mechanical damage or excessive wear.
24. Why do you say in the rotor, the rotor is abnormal vibration and the important reasons of early damage of the bearing? Answer: due to installation error between the rotor and rotor, bearing after deformation, the influence of such factors as environment temperature changes, is likely to cause of the poor, the rotor of the undesirable shafting, due to the coupling of stress change, change the rotor journal and bearing the actual work position, not only changed the working state of the bearing, also reduces the natural frequency of the rotor shaft system, so in the rotor is lead to abnormal vibration of the rotor occurs and the important reasons of early damage of the bearing.
25. The measurement and review journal ellipticity and taper standard? A: measurement review sliding bearing diameter of axle ovality and taper should comply with the technical requirements, shall not be more than one over one thousand of the diameter. The rolling bearing diameter of axle ovality and taper is not greater than 0.05 mm.
26. The chemical pump assembly should pay attention to what issues? A: 1) whether the pump shaft bending, deformation; 2) rotor balance status conformed to the standard; 3) the clearance between the impeller and the pump shell; 4) mechanical seal cushion compensation mechanism of the amount of compression is achieved; 5) concentricity of the pump rotor and the volute; 6) the center line of the pump impeller passage and whether centerline of the volute runner; 7) the clearance adjusting between bearing and end cover; 8) sealing part clearance adjustment; 9) motor drive system with variable () increase and decrease the speed of assembly is in accordance with the standards; Find is 10) coupling coaxial degree; 11) mouth ring gap whether accord with a standard; 12) by force of joint bolt.
27. What is the purpose of the pump repair? Asked what? Answer: purpose: through the pump repair, eliminate problems after long time running. Requirements are as follows: 1) elimination, adjust the pump internal cause larger gap of the wear and corrosion; 2) eliminate dirt, dirt, rust inside pump; 3) does not meet the requirements or defective parts repair or replacement; 4) rotor balance experiment examination qualified; 5) test pump and drive alignment and conform to the standard; 6) test qualified, the information is complete, reach requirements of processing.
28. What was the reason for the machine pump power consumption is too large? Answer: 1) the total head and pump lift discrepancy; 2) the medium density, viscosity didn't agree with the original design; 3) pump shaft axis and prime mover inconsistent or curved; 4) rotational part and fixed part friction; 5) impeller mouth ring wear, 6) improper seal or mechanical seal installation.
29. The rotor imbalance causes have? Answer: 1) making error: material density uneven, not alignment, roundness, uneven heat treatment; 2) assembly is not correct: assembly components of the centerline and axis coaxial; 3) rotor deformation: uneven wear, axis deformation under operation and temperature.
30. What is a dynamic unbalance rotor? Answer: there is equal, in the opposite direction, unbalanced particle integrated into two couple is not a day line of rotor.
31. How to prevent in the process of operation time, cavitation phenomenon appear? Answer: time: memory of gas and liquid pump, the pump can't work, flow and pressure tends to zero. Cavitation: occurred within the pump in operation, from the medium inside the pump, flow and pressure change and drop, a hydraulic impact. To pump usually refers to a kind of cavitation occurs in the pump, because of the installation technology pipeline leak, inhalation of gases time few, most are caused by operation and process changes. In the process of operation, process and operation conditions should be stable, operating temperature YiQu lower limit, lower limit pressure YiQu, to avoid or control the occurrence of cavitation phenomenon, in the operation of pump flow wants moderate, minimize the change of pressure and temperature appear larger. Reserved should prevent gas in the pump suction pipe, the standby pump suction to the inlet pressure is negative pressure should be closed.
32. What is a dynamic and static cooperate? Where is the obvious difference between them? Answer: 1) clearance fit: hole is greater than the actual size of the actual size of the pump of cooperation; 2) static cooperates: shaft hole is greater than the actual size of the actual size of cooperation; 3) obvious difference: dynamic coordination, shaft hole to do relative movement; Interference fit: shaft and hole without relative motion.
33. What are the requirements for equipment maintenance to the four cardinal? A: neat, cleaning, lubrication, security
34. The working principle of the labyrinth seal is what? Answer: labyrinth: there are several sequential ring seal of tooth, tooth and a series of throttling clearance is formed between the rotor and expansion space, fluid after many twists and turns of the channel, the multiple throttling and produce a large resistance, make the fluid to leak, the purpose of sealing.
35. What is the interchangeability of parts? What's the main for? Answer: 1) the parts can be used mutual exchange, and can meet the requirements of the indicators of the original parts, called the interchangeability of parts. 2) mainly played the convenience of maintenance, reduce maintenance time, improve equipment utilization and efficiency.
36. What is the power type pumps? A: power pump continuously send energy to be liquid, make its speed kinetic energy and pressure increase, who are mainly speed increases, then its speed is reduced, can make the most of the kinetic energy into pressure, use has increased the liquid to be delivered after pressure to transportation, such as: 1) the vane pump, it consists of a centrifugal pump, mixed flow pump, axial flow pump, vortex pump, etc; 2) jet pump, including the gas jet pump, liquid jet pump, etc.
37. What is a positive displacement pump? Answer: positive displacement pump in the process of periodically change the pump cavity volume, in order to function and the periodical change of displacement transfer ability to be transported liquid, so the pressure rise directly to the pressure required to achieve value after delivery, such as: 1) the reciprocating pump, piston pump, plunger pump, diaphragm pumps, extrusion, etc.; 2) rotor pump, including gear pump, screw pump, roots pump and rotary piston pump, vane pump, pump, flexible rotor pump, crankshaft peristaltic pump, etc.
38. What are the main performance parameters of the pump? A: mainly include: flow, lift, NPSH, rotational speed, power and efficiency, etc.
39. The backup device: why do you want to turning on a regular basis? Barring should pay attention to? Answer: 1) the backup device turning on a regular basis, is a test equipment operation is flexible, presence of jam phenomenon; 2 it is to prevent the bearing bending deformation, such as real standby. 2) should be paid attention to while turning: one is the plate of the stop position of the rotor and the original position as an Angle of 180 degrees; The second is to sling lubrication oil pump should be to, after turning, in order to prevent damage to the bearings.
The 40 more than rated current of pump what harm is there? Answer: in the rated voltage, rated current is the motor rated power under the condition of normal work of the current, if more than rated current, the motor easy to overheat, relay protection device, make the pump stop, such as relay protection device is not bad action or action easily burning motor, pump damage to the machine.
41. The pump and the main content of the inspection have? Answer: 1) check the pressure gauge, the ammeter indicates whether the value in the specified area, and stable; 2) check the running sound is normal, do you have any noise; 3) bearings, motor temperature is normal (no more than 60 degrees); 4) check whether the cooling water is clear, whether packing pump, mechanical seal leakage, such as whether the leak within the scope of the permit; 5) check if connection parts tightly, anchor bolt is loose; 6) check whether the lubrication is good, the oil level is normal;
42. The maintenance staff to maintenance, plant operators should do what work? Answer: 1) check the maintenance working ticket is consistent with the actual repair equipment a number; 2) contact the shift supervisor for zone electrical power failure; 3) to the maintenance staff to provide equipment damage situation and repair the site; 4) cooperate with maintenance at the scene and supervise the maintenance quality. 5) after the repair, contact transmission, commissioning; 6) after normal operation, report to the monitor of the duty, recorded at the same time.
43. The pumping, the action of the outlet valve is what? Answer: 1) the pump inlet valve is slurry pump maintenance and system isolation or cut parts, cannot be used to adjust flow, should be fully open; 2) the outlet valve is to regulate traffic and open and stop when make the pump and system isolation, to cut off the parts.
44. The pumps used in chemical production according to what the seal? Answer: according to the process conditions and work pressure, choice of medium corrosion condition of rotating speed.
45. What are the types of flat gasket seal? A: 1) the non-metallic gasket seal; 2) non-metal and metal composite gasket seal; 3) metal gasket seal.
46. What are the main reason of gasket leaking? Answer: 1) cause the leak of design; A, incorrect flange and the flange sealing surface. B gasket improper selection; C flange and bolt improper material selection; 2) cause the leak of manufacture, installation and operation; A flange and gasket processing precision do not meet the technical requirements; B when tightening bolts, improper operation, cause gasket wide mouth; C flange seal face is clean, there are impurities.
47. What is the mechanical seal? Answer: seal, mechanical seal, also called face is by at least a pair of end face of vertical axis rotation, in under the action of fluid pressure and compensation mechanism, make the two ends together, and the relative sliding and prevent fluid leak device.
48. The pump and there are several kinds of commonly used seal form? A: there are two kinds, dynamic seals and static seals.
49. What are the main cause of mechanical seal leakage? Answer: 1) between the ring and static ring seals and wear is too big, unreasonable design load coefficient, make the seals to produce the phenomenon such as crack, deformation and breakage. 2) several auxiliary seal ring have defects or defects due to improper assembly, and select auxiliary seal ring is not suitable for working condition of the medium. 3) spring pre-tightening force not enough or after long time operation, fracture, corrosion, relaxation, coking, as well as the working medium of crystallization suspended particles or long time accumulation of congestion in spring clearance, cause spring failure, compensation seal ring can't float, leak; 4) due to the dynamic and static ring seals and shaft centerline verticality deviation is too big, make the seals bonding imprecise cause leakage; 5), because of the large shaft axial channeling momentum with seal related accessories or quality is bad, are prone to leakage phenomenon.
Of mechanical seal friction pair 50. According to what material? Answer: according to the nature of the medium, working pressure, temperature, sliding speed and so on factors to choose, sometimes also consider start or liquid membrane damage when the ability of the dry friction under a short time.
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