Centrifugal pump generally prone to the following problems: a. The pump can not start or start the load is large and the reasons are as follows: (1) The prime mover or power supply is not normal. Approach is to check the power and prime mover situation. (2) pump stuck. Approach is to use hand-drive coupling inspection, disintegration inspection, if necessary, to eliminate static and dynamic part of the fault. (3) packing pressed too tight. The treatment is to relax the packing. (4) discharge valve is not closed. Approach is to close the discharge valve, restart. (5) balance pipe is not smooth. Approach is to clear the balance tube. b. The reason for the pump is not drained and the treatment method is as follows: (1) insufficient pump (or the pump is not discharged). The method is to re-pump. (2) The pump is not turning properly. Approach is to check the direction of rotation. (3) pump speed is too low. Approach is to check the speed, increase speed. (4) filter plug, the valve is not working. Approach is to check the filter to eliminate debris. (5) suction height is too high, or vacuum suction tank. Approach is to reduce the suction height; check the suction tank pressure. C. After the pump drain interrupt reason and treatment as follows: (1) suction pipe leakage. Approach is to check the suction side of pipe connections and stuffing box seal. (2) Suction side of the pump gas is not discharged finish. Approach is to require re-irrigation pump. (3) Suction side suddenly blocked by foreign bodies. Approach is to stop the pump processing foreign body. (4) Inhalation of large amounts of gas. Approach is to check whether the inlet whirlpool, submerged depth is too shallow. d. The reasons for the lack of flow and treatment are as follows: (1) with b, c. Approach is to take appropriate measures. (2) System static head increased. Approach is to check the liquid height and system pressure. (3) resistance loss increases. Approach is to check the pipeline and check valve and other obstacles. (4) shell and impeller wear ring wear too much. Approach is to replace or repair wear ring and impeller. (5) other parts of leakage. Approach is to check the seal and other parts. (6) pump impeller blockage, wear, corrosion. Treatment is cleaning, inspection, exchange. e. The cause of insufficient head and its treatment are as follows: (1) Same as (1), (2), (3), (4), c (1), d (6) of b. Approach is to take appropriate measures. (2) impeller mounted anti (double suction wheel). Approach is to check the impeller. (3) liquid density, viscosity and design conditions do not match. The solution is to check the physical properties of the liquid. (4) the operation flow is too large. The solution is to reduce the traffic. f. The reasons for the large power consumption and processing methods are as follows: (1) impeller and wear rings, grinding impeller and shell. Approach is to check and repair. (2) Same as e (4) above. The solution is to reduce the traffic. (3) Liquid density increases. The solution is to check the liquid density. (4) packing pressed too tight or dry friction. Treatment is to relax the filler, check the water seal tube. (5) bearing damage. Approach is to check repair or replacement of bearings. (6) speed is too high. Approach is to check the driver and power supply. (7) shaft bending. The treatment method is to correct the pump shaft. (8) Axial force balance failed. Approach is to check the balance hole, the return pipe is blocked. (9) Coupling misalignment or axial clearance is too small. Approach is to check the alignment and adjust the axial clearance. g. Pump vibration or abnormal sound causes and treatment are as follows: (1) with c (4), f (5), (7), (9). Approach is to take appropriate measures. (2) The vibration frequency is 0 ~ 40% working speed. Too large bearing clearance, loose bearings, impurities in the oil, bad oil (viscosity, temperature), blistering due to air or process fluid, poor lubrication, bearing damage. Treatment is checked, take appropriate measures, such as adjusting the bearing clearance, remove impurities in the oil, replace the new oil. (3) Vibration frequency is 60% ~ 100% working speed. The same bearing on the problem (2), or seal gap is too large, Loosening ring, seal wear. Approach is to check, adjust or replace the seal. (4) Vibration frequency is 2 times working speed. Misalignment, loose coupling, seal friction, shell deformation, bearing damage, bearing resonance, thrust bearing damage, shaft bending, poor cooperation. Approach is to check, take appropriate measures to repair, adjust or replace. (5) The vibration frequency is n times the working speed. Pressure pulsations, misalignment, shell deformation, seal friction, support or foundation resonance, piping, machine resonance, treatment methods are the same (4), strengthening the foundation or piping. (6) Vibration frequency is very high. Shaft friction, seals, bearings, imprecise, bearing jitter, poor shrink fit and so on. The same treatment (4). h. bearing the causes of heat and treatment are as follows: (1) bearing pad scraping unqualified. Approach is to repair bearing pads or replacement. (2) bearing clearance is too small. Approach is to re-adjust the bearing clearance or scraping. (3) Lack of oil, poor oil quality. Approach is to increase the oil or replace the oil. (4) bearing assembly bad. Approach is to check the bearing assembly requirements, eliminating unmet requirements. (5) cooling water circuit. Approach is to check and repair. (6) bearing wear or loose. Approach is to repair the bearing or scrapped. If the pine association, compound the relevant bolts. (7) shaft bending. The treatment method is to correct the pump shaft. (8) rejection oil ring deformation, rejection oil ring can not rotate, with no oil. Approach is to update the oil slinger. (9) Coupling misalignment or axial clearance is too small. Approach is to check the alignment and adjust the axial clearance. i. The cause of the shaft seal heat and treatment are as follows: (1) packing pressed too tight or friction. Treatment is to relax the filler, check the water seal tube. (2) water seal and water seal tube dislocation. Approach is to re-check alignment. (3) flushing, cooling well. Approach is to check flushing cooling circulation tube. (4) Mechanical seal is faulty. Approach is to check the mechanical seal. j. The reasons for the rotor movement and processing methods are as follows: (1) improper operation, operating conditions away from the pump design conditions. Approach: Strict operation, the pump is always running near the design conditions. (2) the balance is not smooth. Approach is to clear the balance tube. (3) balance plate and balance plate seat material not meet the requirements. Approach is to replace the material to meet the requirements of the balance plate and balance plate seat. k. The cause of the water hammer and the treatment is as follows: (1) due to a sudden power outage, resulting in system pressure fluctuations, the emergence of negative pressure discharge system, dissolved in the liquid bubbles to escape the presence of gas in the pump or pipe. The treatment is to purge the gas. (2) high pressure liquid column due to a sudden power outage quickly influx, the impact of the pump outlet check valve plate. The treatment method is to rebuild the disposition of the pipeline and the pipeline accessory of the irrational discharge system of the pump. (3) The outlet pipe valve is closed too fast. The method is to slowly close the valve 1, the main working principle of centrifugal pump is what? The motor drives the impeller to rotate at a high speed, causing the liquid to generate centrifugal force. Due to the centrifugal force, the liquid is thrown into the side runner to discharge the pump or enter the impeller of the next stage, so that the pressure at the inlet of the impeller is reduced and forms with the pressure acting on the suction liquid Differential pressure, differential pressure in the liquid inhalation pump, due to the non-stop rotation of the centrifugal pump, the liquid is continuously inhaled or discharged. 2, lubricants (fat) What are the effects? Lubrication and cooling, washing, sealing, vibration damping, protection, unloading. 3, before using which three-tier oil filter? The first level: between the original oil barrel and the fixed barrel; second level: between the fixed oil barrel and the oil pot; the third stage: between the oil pot and the refueling point. 4, what is equipment lubrication "five fixed"? Fixed: according to the provisions of the point of fuel; timing: according to the provisions of the lubrication time to refuel, and regularly change the oil; quantitative: quantitative consumption by consumption; qualitative: according to different models choose different lubricants and maintain oil quality standards; Set people: Every refueling site must have someone responsible. 5, pump oil in water what harm? Moisture can reduce the viscosity of lubricating oil, reducing the strength of the film, reducing the lubricating effect. Water below 0 ℃ to freeze, seriously affecting the low temperature fluidity of lubricants. Moisture can accelerate the oxidation of lubricants and promote the corrosion of metals by low molecular weight organic acids. Moisture will increase the foam of the lubricant, making the lubricant prone to foam. Moisture can rust metal parts. 6, pump maintenance What are the contents? Seriously implement the job responsibility system and equipment maintenance and other rules and regulations. Lubrication equipment to do "five", "three filter", lubrication complete, clean. Maintenance tools, safety equipment, fire equipment, complete well, put it neatly. 7, the common standard seal leakage? Packing Seal: Light oil is less than 20 drops / min Heavy oil is less than 10 drops / min Mechanical seal: Light oil is less than 10 drops / min Heavy oil is less than 5 drops / min 8, what should be done before starting the centrifugal pump? Check the pump and the outlet pipelines, valves, flanges have tight, whether the loosening bolts, coupling (on the wheel) is good, pressure gauge, thermometer is easy to use. Coil 2 to 3 laps, check whether the rotation is flexible, with or without abnormal sound. Check the quality of lubricants is qualified, the oil is maintained at the window to see the 1/3 to 1/2 between. Open the inlet valve to close the outlet valve, open the pressure gauge hand valve and each cooling water valve, flushing oil valve. The pump that delivers hot oil must be preheated to a temperature difference of 40 to 60 ° C to the operating temperature before starting, and the maximum temperature must not exceed 40 ° C of the operating temperature at a temperature increase rate of 50 ° C / h. Contact electrician to send electricity. No explosion-proof motor to start the fan or to give proof hot air, purge pump combustible gas. 9, how to switch centrifugal pump? First of all should be prepared to open the pump before the preparatory work, such as pump warm-up. According to the pump outlet flow, current, pressure, level and other related parameters switch each other, the principle is to start the standby pump until all parts normal, the pressure up, slowly open the outlet valve, and slowly switch the pump is switched off the export Valve until the pump is switched out of the outlet valve is completely shut off, stop the pump is switched, but should be due to flow switching and other parameters to minimize fluctuations. 10, why the centrifugal pump plate does not start when the car? Centrifugal pump plate does not move the car, indicating that the internal pump failure, the failure may be what the impeller stuck or excessive bending of the pump shaft, or pump dynamic and static part of the rust died, or the pump pressure is too high. If the pump plate does not move the car and forced to start, strong motor power driven pump shaft strong action will cause damage to the internal parts, such as shaft breakage, distortion, impeller broken, the motor coil burned, may also make the motor trip, start failed. 11, what is the role of oil seal? Cooling seal parts; lubricated friction pay; to prevent taking the time to damage. 12, Why do spare pump regularly turning? The role of regular car plate there are three: to prevent dirt in the pump stuck; to prevent the shaft deformation; crank can also bring the lubricating oil to the lubrication point to prevent rust, the bearings are lubricated in the emergency immediately Drive 13, hot oil pump before starting Why preheat? If you do not preheat the hot oil pump to start, hot oil quickly into the cold pump body, will make the pump body uneven heating, the upper part of the large amount of thermal expansion, the lower part of the small amount of thermal expansion, the pump shaft bending, or the pump body Of the mouth ring and the rotor seal stuck; forced start will cause wear, hold the shaft, shaft accident. If you do not preheat the large viscosity oil, the oil will condense in the pump body, resulting in not on the amount of start-up, or because the starting torque is large, the motor trip. Due to not fully preheated, will make the pump around the uneven thermal expansion, the static sealing point leakage. Such as export, import flange, pump cover flange, balance pipe leakage, and even cause fire, explosion and other serious accidents. 14, hot oil pump should pay attention to what warm-up? Preheat process to be correct. The general process is: pump outlet → inlet and outlet across the line → preheating line → pump → pump inlet. Preheat valve can not be opened too large, to prevent the pump reverse. Pump body preheat speed generally can not be too fast, should be less than 50 ℃ / h. Under special circumstances can be through to the pump steam, hot water and other measures to speed up the preheating speed. Preheat every 30 to 40 minutes should be car 180 °, so as to avoid uneven heating and bending the pump shaft. Bearing box, pump seat cooling water system to open to protect the bearings and shaft seals. 15, hot oil pump should pay attention after deactivation? Various parts of the cooling water can not be stopped immediately, to wait until all parts of the temperature dropped to normal temperature before cooling water. Prohibit the use of cold water pump body, so as not to pump too fast cooling, the pump deformation. Close the pump outlet valve, inlet valve, inlet and outlet valves. Turn the car 180 ° every 15-30 minutes until the pump temperature drops below 100 ° C. 16, the centrifugal pump in operation abnormal fever what are the reasons? Fever is the performance of mechanical energy into heat energy, causing abnormal pump fever common causes are: accompanied by noise heating, usually bearing ball cage isolation damage. Bearing sleeve sleeve bearing loose, loose gland before and after, due to friction caused by fever. Bearing hole is too large, causing the bearing outer ring loose. Pump body foreign body. Large rotor vibration, ring seal wear. Pump down or pump load is too high. Rotor is not balanced. Too much oil or too little oil and unqualified. 17, centrifugal pump vibration what are the reasons? Rotor is not balanced. Pump shaft and motor misalignment, round rubber ring aging. Too much bearing or seal ring wear creates eccentric rotor. Pump pump or pump gas. Suction pressure is too low, the liquid vaporization or near vaporization. Axial thrust becomes larger, causing the string axis. Improper lubrication of bearings and packing, excessive wear. Bearing worn or damaged. Impeller partially blocked or external accessory line vibrating. Lubricant (fat) too much or too little. Pump base stiffness is not enough, loose bolts. 18, centrifugal pump vibration, bearing temperature standard is what? Vibration standards for centrifugal pumps: speed less than 1500vpm, vibration less than 0.09mm. Speed ​​1500 ~ 3000vpm, vibration less than 0.06mm. Bearing temperature standards: sliding bearings less than 65 ℃, rolling bearings less than 70 ℃. 19, pump normal operation, how much cooling water is appropriate? Pump in normal work, open the size of the cooling water to the drainage temperature of about 40 ℃ the most appropriate. At this point contact with the discharge water a little temperature, the cooling effect is best. In particular, the end seal of the cooling water can not be opened too much in the winter, in order to prevent dynamic and static ring seal due to low water temperature and hardening, loss of elasticity of the seal failure. 20, when the centrifugal pump time what? When a pump in service starts to pump down, it suddenly emits noise, vibration, pressure, reduced flow, and reduced current. Pumping serious, the pump will occur a strong vibration, the pressure back to zero, no liquid pump out. 21, bearing box fever what are the reasons? Pump shaft and motor shaft are not concentric. Lubricant (fat) too much or too little, oil (fat) deterioration. Broken oil ring or jump out of the fixed position. Axial thrust increases. Insufficient cooling water or interruption. Bearing wear. The flow rate is too small to pump close to the pump down state. The foundation is not strong, the rotor imbalance, loose bolts and other causes of pump vibration. 22, the pump in the winter Why frost? Volume expansion of water occurs below sub-zero. If the water remaining in the pump body is not cleaned out, the force generated by the volume expansion at low temperature will cause the pump body to burst, resulting in unnecessary damage. Antifreeze methods are the following: Pai idle pump storage of water. Keep cooling water flowing. Insulate the pump or steam, hot water with heat. Stand-by pump to keep the entrance circulation. 23, pump frozen after how to deal with? After the pump is frozen, it must never be blown directly with steam to prevent rupture due to uneven thermal expansion of the pump. After the first pump with cold water pouring frozen, and then to be coiled car, you can use steam or hot water pouring. 24, why the pump cooling? Pump in the operation of the liquid flow generated between the pump body friction, rotating parts and fixed parts such as the bearing ball and the inner and outer rings, bushings and packing and other parts will produce friction due to friction will produce heat, at the same time as the medium temperature is high conduction Machine pump, so that the pump heat, the purpose of cooling is to reduce the pump body, pump base, bearing housing, shaft seal at the temperature to prevent these parts due to temperature deformation, aging and damage. 25, under what circumstances the motor to emergency stop? Endanger personal safety. Motor smoke or smell, when the fire. A large vibration or axial stringing occurs. Body or bearing fever to the limit. Slow motor speed with abnormal sound. 26, explain the type of centrifugal pump made in China, such as 100Y â…¡ - 100 × 2A is what? 100 - the diameter of the pump inlet Y - single-stage centrifugal pump â…¡ - pump material code, the second carbon steel corrosion-resistant temperature 200 ~ 400 ℃ A - the first turning of the outer diameter of the impeller 27, how to determine the steam Erosion phenomenon? Fierce noise in the pump. Export pressure is not stable, can not hit the amount of serious. Pump body vibration. Medium temperature increases. 28, pump 1146 (Diaphragm metering pump) Driving: Hand pressure compensation valve stem before driving, at this time, one side of the membrane cavity filled with oil, one side of the gas discharge chamber, until the bubble is no longer upstairs. After driving, pump in the plunger for inhalation movement (no pressure in the discharge tube) in the above method will be compensated valve stem pressure open, the action of the safety valve to jump open several times, so that the safety valve at the air discharge until the bubbles so far. At this time if the impact of sound or vibration phenomenon, indicating excessive fuel should be in the plunger for the discharge stroke, light pressure compensation valve stem by hand for a short discharge, so that the extra discharge until the vibration or shock sound elimination After the pump runs smoothly. Parking: cut off the power, stop the pump operation. Close the import and export pipeline valves, shells should pay attention to open before driving. Maintenance: Lubricant Replacement: Lubricant is changed once a month, adding proper amount of 23 # or 30 # engine oil. Pump in operation, the main part of the temperature provisions: the motor allows the maximum temperature of 70 ℃; adjust the base oil temperature not exceeding 65 ℃; filler and the temperature does not exceed 70 ℃. Leakage: pump in normal operation, the leakage shall not exceed 15 drops per minute, 2), 3) If there are over-standard, should contact the relevant units for processing, eliminate hidden dangers. 29, the workshop in the pump lubrication using what kind of lubricating oil (fat)? Pumps 1350/1, 2 use calcium-based lubricants. The pump 1146 uses 20 # or 30 # machine oil. The rest of the pumps are used 46 # mechanical oil. 30, the use and maintenance of pump 1113 1), familiar with the pump 1113 flushing oil, sealing oil, cooling water, cooling steam flow 2), the use of flushing oil: Open the flushing oil before the pump to run for 10 minutes before stopping the pump Flush the oil; open the flushing oil before stopping the pump and stop flushing oil for 10 minutes after stopping the pump. Drive: Repair the first start: observe the motor steering, pump rotation from the motor side should be counterclockwise; lubricating oil tank with qualified 46 # mechanical oil to 2/3 oil level; oil seal, cooling steam cast, cooling water cast , Start the pump before the cooling water is small, to prevent the cooling water string into the tank; the pump preheat, preheating the line with preheating oil preheating, exhaust pump exhaust row above the pump exhaust air, and then open the large entrance valve. Start the motor and note that the pump can not be operated for a long period of time in the lower operating range. Stop pump: close the pump outlet valve, stop the motor, crank once. 3), routine maintenance: Check the oil level, the oil level shall not be less than 1/3; Check the bearing box surface temperature is not greater than 80 ℃, the maximum oil seal mechanical seal does not exceed 5cm3 / h, pump running smoothly without vibration, no noise ; Motor running smoothly, no noise, no abnormal temperature in all parts of high temperature; Lubricants Lubricating time according to the workshop to be replaced, add lubricating oil, remove the constant level filling cup, refueling back into place. Seal oil pressure higher than the pump inlet pressure of about 0.2MPa is appropriate. 31, how the pump is classified? Pump classification generally according to the principle of the role of the pump is divided into two types of vane and volumetric. Vane pump impeller is rotated by the pump fluid, the vane pump blade structure due to the different forms of centrifugal pump is divided into, axial flow pump and vortex pump, etc., is the use of positive displacement pump chamber volume of the cycle Sexually Transmitted Liquids. Divided into reciprocating pump (piston pump, piston pump, diaphragm pump, etc.) and the rotor pump (gear pump and screw pump, etc.). Pumps are often named according to the purpose of the pump, such as: pumps, pumps, ammonia pumps, liquid hydrocarbon pumps, mud pumps, corrosion pumps, condensate pumps. 32, centrifugal pumps, reciprocating pumps, rotor pumps, vortex pumps have their own characteristics? Type Centrifugal Pump Reciprocating Pump Rotor Pump Vortex Pump Uniform Flow Large Flow Varies with Pipeline Unbalanced Flow Constant, Little Change Due to Indenter Uniform Small Flow Constant, Low Reciprocating Pump Flow changes with the pipeline changes Head is generally not high For a certain flow can only provide a certain lift High For a certain flow Can supply a different lift by the pipeline system with a higher reciprocating pump Certain flow can only provide a certain head The highest efficiency of about 70% at the design point of the highest, the more far off, the lower the efficiency of 80% of the supply of different head, the efficiency remains the maximum value of 0.6 ~ 0.90 Leakage at high head, so that leakage reduced 25 ~ 50% Structure Simple, cheap, easy to install High-speed rotation, can be directly connected to the motor Parts and more complex structure Vibration is too large, not fast, difficult to install Large size, take up more than the need to inhale the valve When transporting corrosive liquids, the structure is more complex No valves Can be connected directly with the motor less parts, but the manufacturing precision higher. Simple and compact, high suction height High-speed rotation, can be directly connected with the motor The impeller and the pump casing requires a very small gap between the shaft seal device requirements, can not leak operation Before driving to be filled with water, can not be run Gas maintenance, easy to operate Valve can be easily adjusted to prevent traffic flow due to blockage and damage Parts of the more prone to failure, maintenance trouble Can not use the outlet valve can only use the branch valve to adjust the flow rate Headflow can be maintained high Efficiency check than the centrifugal pump complex than the reciprocating pump easy to use the outlet valve can only be adjusted with the branch valve flow power increases with the flow rate decreases, the outlet valve should be open when driving the same token, the flow regulating branch valve The scope of application can transport corrosive or suspension, the viscosity of the fluid is not applicable, the general flow, and the head is not high-lift, low-flow cleaning liquid high lift, low flow, especially suitable for conveying viscous liquids such as oil For small flow and high head liquid, but can not transport dirty liquids 33, centrifugal pump axial force is how to eliminate? 1), single-stage pump to balance the axial force measures are: â‘ double suction impeller; â‘¡ open balance hole; â‘¢ balance pipe 2) multistage centrifugal pump axial force balance measures are: impeller symmetrical arrangement; â‘¡ balance drum Plus balance pipe; â‘¢ Balance plate plus balance pipe; â‘£ Balanced drum and balance plate plus balanced pipe combination type balance measures. 34, under what circumstances to pump cooling? What is the role of cooling water? When the pump medium temperature is greater than 100 ℃, the bearing needs to be cooled, more than 150 ℃, the sealed chamber generally need to be cooled, greater than 200 ℃, the pump bearing generally require cooling. The role of cooling water is: to reduce the bearing temperature; take away a small amount of fluid leaked from the shaft seal and the transmission of friction heat; reduce packing temperature, improve the working conditions of mechanical seals to extend its life; cooling pump bearings To prevent concentricity shift between pump and motor due to thermal expansion. Cooling water The liquid is best to use circulating water or fresh water, and should be reused with demineralized water only when its full hardness is greater than 4.5 mmq / l. 35, what is the phenomenon of cavitation? When the pressure at the inlet of the impeller is lower than the saturated pressure of the working medium, a part of the liquid will be evaporated (ie, vaporized). After the evaporation of bubbles into the high pressure area, the sudden condensation of condensation, so the liquid around here to replenish, resulting in hydraulic impact, a phenomenon known as cavitation. The continuous local impact load will make the material surface gradually fatigue damage, causing the metal surface erosion, and then the size of honeycomb-shaped cavities. Cavitation process instability, causing the pump vibration and noise, at the same time due to cavitation bubbles Plug the impeller channel, so at this time the flow, lift are reduced, the efficiency of decline, it should prevent cavitation. 36, hot pump and cold pump What is the difference? 1) The difference between the medium temperature, 200 ℃ below the cold oil pump (20 ~ 200 ℃), the above hot oil pump (200 ~ 400 ℃); 2) to seal oil to distinguish the general hot oil pump seal oil, Cold pump will not; 3) to the material to distinguish between hot oil pump to carbon steel, alloy just for the material, the pump bracket with circulating water cooling, and cold pump with cast iron can, pump bearing cooling; 4) pump model Medium heat pump with the letter R, said the cold pump with the letter J; 5) standby state, the hot oil pump to be preheated, cold pump without preheating. 37, the pump often appear in the abnormal noise? 1) rolling bearing abnormal new replacement of rolling bearings, assembly radial stress is too large, the rolling body rotation difficult, it will make a small buzz, then the bearing temperature will rise; if the bearing body of oil shortage, running Rolling bearings will emit a uniform whistle; Rolling body and the spacer gap is too large, the operation can be issued a large chime sound; rolling bearings in the outer ring surface or rolling surface peeling, the operation will be issued intermittent Of the impact and beating; if the rolling bearing damage (including the isolation frame is broken, the rolling body broken, cracks in the inner and outer rings, etc.) cracked pops in the operation, La La sound. 38, pump to the liquid to provide what energy? Pump to provide static pressure liquid, potential energy, dynamic pressure energy. 39, pump and motor drive coupling several? A belt drive, gear box drive, the motor direct linkage of three. 40, what is the pump flow? The amount of liquid discharged from the pump outlet pipe per unit time is called the flow rate and is expressed by Q. Flow can be divided into weight flow and volume flow to volume flow-based. Weight flow refers to the weight of the flow passed in a unit of time. Unit: kg / second, T / and so on. Volumetric flow is the volume of fluid passed in a unit of time. Unit: M3 / hour. 41, what is the pump head? Pump head is the liquid after the pump through the increase of its energy value, usually expressed by H, unit: m, unit of measurement: kg / cm2. 42, what is the pump flow rate? Pump flow rate is the unit of time, the fluid through the distance, usually expressed in meters, units of measurement: m / s. 43, what is pressure? The pressure on the unit area is called pressure. Unit: MPa 44, what is the atmospheric pressure? Atmospheric pressure: the air pressure on the surface of the object unit is called atmospheric pressure, or atmospheric pressure. We call the pressure generated by the mercury column equivalent to 760mm height to standard atmospheric pressure or physical pressure. In industrial production in order to facilitate the calculation, commonly used 1kg / cm2 as the unit of fluid pressure, called an atmospheric pressure, expressed as follows: 1 engineering atmospheric pressure = 760 mm mercury (Hg) = 10.332 m water column 1 kg / cm2 = 10000 Kg / m 2 45, what is the absolute pressure in the equipment? In production, the spring pressure gauge is usually used to measure the pressure in the equipment. Because the pressure gauge is installed in the atmosphere and is itself affected by the atmosphere, the pressure (gauge reading) seen on the gauge needs to be increased by one atm. Is the absolute pressure in the device, for example: gauge reading 4.2kg / cm2 +1kg / cm2 = 5.2kg / cm2, 5.2kg / cm2 is the absolute pressure in the device. 46, what is the vacuum? What is the unit? The so-called vacuum is pumping all the air in the equipment, negative pressure generated in the device, the size of the negative pressure is the level of vacuum, said: mm water column. Can also be interpreted as the pressure within the device is less than the value of atmospheric pressure is called the degree of vacuum, the lower the vacuum, the higher the absolute pressure within the device, whereas the lower the absolute pressure within the device, the higher the degree of vacuum. 47, what is the fluid density? Density is the mass of an object in a unit volume. If G is the mass of the object and V is the volume of the object, the density Ï of the object can be expressed as Ï = G / V. Units of density are usually expressed in kg / m3 or g / cm3. Under normal circumstances, the fluid density changes with temperature changes, the higher the temperature, the smaller the density, on the contrary, the lower the temperature decreases, the greater the density becomes. 48, what is the proportion of fluid? The ratio of the severity of a fluid to that of pure water at 4 ° C is called the specific gravity. The specific gravity of any fluid should be equal in magnitude to that of a fluid, but there is no unit. The proportion of fluid is different with the temperature changes, the higher the temperature, the smaller the proportion. 49, what is power? Power refers to the size of work done in a unit of time, commonly used symbols N to represent. Units KW, HP, kg / s, the relationship between them is: 1 kW = 102 kg m / s 1HP = 75 kg m / s so 1 kW = 1.36 horsepower 1 horsepower = 0.735KW 50, what is the pump shaft power? The shaft power of the pump is also the design power given by the nameplate, which is the power delivered by the prime mover to the pump, indicated by the symbol Nt, in kilowatts (kW) or horsepower (hp). 51, what is the effective pump power? The difference between effective power and shaft power is the power lost in the pump, the power required for the liquid in the pump per unit time, or the shaft power minus the lost power. N = effective = rQH / 75 (Hp) Where r --- heavy liquid (kg / m3) Q --- pump flow (M3 / sec) H --- pump The head (m) 52, what is the efficiency of centrifugal pump? Centrifugal pump efficiency is the ratio of effective power and shaft power pump efficiency, commonly used percentage: η = W efficiency / W axis × 100%. 53, pump efficiency, including what kind of efficiency? The total efficiency of centrifugal pumps, including volumetric efficiency, hydraulic efficiency, mechanical efficiency and so on. 54, before the pump to prevent cavitation, what should be done? First drain the residual gas in the pump; in the installation of the pump to reduce the suction vacuum height as much as possible; in operation should be to minimize the liquid heating temperature; to reduce resistance loss in the pipeline; to minimize hydraulic losses in the suction pipe so that The pressure at the inlet of the liquid flowing into the pump is much greater than the saturated vapor pressure of the liquid. Reduce the liquid into the impeller speed, which is to reduce pump speed and flow, but also to prevent cavitation. The use of induction wheel can also improve the pump cavitation. Selection of anti-cavitation ability of the material made of impeller. 55, the phenomenon of cavitation occurs What are the reasons? Occurrence of cavitation phenomena are: the level of inhalation or infusion head height is not enough. Atmospheric pressure is reduced. System pressure is reduced. Media temperature increases, saturated vapor pressure increases (referring to easy vaporization medium). Liquid flow rate increased resistance loss increased. Suction tube resistance. (This depends on the reasonableness of the pump construction and suction pipe installation.) Suction piping leaks air. 56, motor and pump two shaft coupling methods are there? On the wheel coupling; belt drive; gear box speed transmission; host shaft coupling differential pump. 57, axial thrust What harm? Axial thrust of great harm, first of all, axial displacement of the rotor, destroy the concentricity of rotor and overflow, a direct impact on flow and lift, more importantly, due to the displacement of the string axis, the pump rotor and pump Body friction, the bearing subjected to additional load and fever, causing damage to the pump stop pump. 58, axial thrust is the first to destroy which part? As a result of the axial thrust damage caused by the earliest impeller mouth ring face, optical end face to continue after the string shaft damage and damage caused by the bearing pump. 59, why the pump inlet pipeline thick, fine export pipeline? Because the pump draws liquid by its differential pressure. In the case of the same diameter, the pump suction capacity is less than the discharge capacity, and when the suction of liquid less than the discharge of liquid, pump will produce evacuation. Rough inlet pipelines can reduce suction resistance and increase pump suction capacity. The pump inlet line is therefore rougher than the outlet line. 60, centrifugal pump outlet pipe Why install one-way valve? Check valve also known as the valve, it only allows liquid to flow in one direction, but not allowed to reverse flow. The check valve is installed at the outlet of the pump to prevent the pump from being reversed due to the reverse flow of the liquid when the outlet valve is not closed for some reason, causing loosening and dropping off of the nut and other components on the rotor. 61, pump temperature is too high how to deal with? When the pump is in operation, the temperature is too high, you should first identify the cause of the temperature rise in time to deal with. If the pump itself is faulty, check the pump should be stopped. If the operating conditions are not appropriate, the operating parameters should be adjusted to increase the flow rate. If the temperature is too high or the temperature of the conveying medium is too high, it can be cooled by water pouring or wind blowing (water should be slowly cooled, not quench) Water can not be used to cool motors and cables that are overheating, because water is not insulated. If the motor is leaking, it may cause the leaked electricity to pass through the water to the human body, causing an electric shock accident. In addition, if the water into the junction box and other places, will make the insulation damage, a direct impact on the normal operation of equipment and safety in production. 62, why can not reverse the centrifugal pump, idling? Reversal and idling will cause unnecessary loss of centrifugal pump. Reversal will make the pump fixed screws such as bushings, impeller caps and other loose, fall off, causing an accident. During idling, no liquid enters and exits the pump, causing the liquid to generate heat and vibration in the pump friction, causing the parts to be damaged and in severe cases will cause the axle to be axled and cause other accidents. 63, pump why cool? Pump in the operation of the liquid flow generated between the pump body friction, rotating parts and fixed parts such as the bearing ball and the inner and outer rings, bushings and packing and other parts will produce friction due to friction will produce heat, at the same time as the medium temperature is high conduction Machine pump, so that the pump heat, the purpose of cooling is to reduce the pump body, pump base, bearing housing, shaft seal at the temperature to prevent these parts due to temperature deformation, aging and damage. 64, the pump in normal operation, the cooling water to open more suitable? Pump in normal work, the size of the cooling water to open the drainage temperature of about 40 ℃ is most appropriate. At this point contact with the discharge water a little temperature cooling the best. In particular, the end seal of the cooling water can not be opened too much in the winter, in order to prevent static and dynamic ring seals because the water temperature is too low and harden, loss of elasticity of the seal failure. 65, choose the principle of pressure gauge pump is what? In the pulsating load: head range = (2 ~ 3) times the working pressure, keep the pointer in 1/2 to 1/3 of the scale. Under uniform load: head range = (1.5 ~ 2) times the working pressure, keep the pointer in 1/2 ~ 2/3 scale. 66, Centrifugal pump intact only what aspects? Centrifugal pump intact includes four aspects: normal operation, good performance. Internal parts without damage, quality meets the requirements. Main body neat, zero accessories complete. Technical information is complete and accurate. 67, the normal operation of centrifugal pumps, including the effectiveness of good What content? Pressure, flow steady, the outlet pressure to meet the normal production needs, or to reach the nameplate capacity of more than 90%. Lubrication, smooth cooling system, oil rings, bearing boxes, such as liquid-level tube easy to use. Selection of lubricants in line with the provisions of bearing temperature in line with standards. Smooth operation without noise, string axis and vibration meet the standards. Shaft seal leakage standards. Pump installation quality inspection: 5.1 Before installation should check the following technical information: 5.1.1 machine's certificate of delivery. 5.1.2 manufacturer of important parts manufacturing quality inspection certificate and the machine commissioning record. 5.1.3 Installation plan of machine and equipment, installation drawing, general assembly drawing, main parts drawing, consumable parts drawing and installation manual. 5.1.4 packing list of the machine. 5.2 unpacking inspection of the machine 5.2.1 Check the name of the machine, model, size, packing number, the number of boxes and check the packaging status. 5.2.2 Check random technical information and special tools are complete. 5.2.3 The appearance of the host, ancillary equipment and zero, parts and check the zero, the variety of parts, specifications, quantity and so on. 5.2.4 Inspection should be submitted after the inspection record of the visa. 5.2.5 The machine and the zero, parts, if not installed, should take appropriate protective measures, safekeeping, prevent deformation, damage, corrosion, aging, confusion or loss and so on. 5.2.6 Where the electrical equipment supporting the electrical, instrumentation and other accessories, should be carried out by the professionals acceptance, safekeeping. 5.3 Installation Procedure: Basic Acceptance → The machine is in rough level → Pump secondary grouting → Health → Jingping, horn spot welding → Basic secondary wiping surface → disintegration cleaning → centering → single trial operation. 5.4 Pre-installation basis The middle of the transfer: 5.4.1 The basic appearance and geometric dimensions of the installation unit acceptance and pass. 5.4.2 Basic information Acceptance. 5.4.3 elevation base line and the basic vertical and horizontal centerline have been drawn. 5.4.4 The secondary grouting should be shovel out the basic surface of the grout. The depth of pitting should not be less than 10mm and the density should be 3 ~ 5 points within 10mm × 10mm. The surface should not be oily or loose. 5.4.5 Place the foundation surface (about 50mm to the circumference) of the foundation surface should be shoveling level, the level of allowable deviation of 2mm / m. 5.4.6 Bolt hole debris, mud and other debris and water, must be cleaned. 5.4.7 Machine base size and location of the allowable deviation in the table below Machine base size and location of the allowable deviation ( mm )