Inspection content, methods, and standards for liquid ring vacuum pumps

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Maintenance work: Minor repair ① Inspect and tighten all connection bolts； ②Replace the packing and adjust the mechanical seal ； 　　③Inspect the coupling, replace the elastic rubber ring, and adjust the coaxiality of the coupling ； ④Inspect the bearings and replace the lubricating oil (grease) ； 　　⑤Clean and inspect the circulating water system. 　　Medium repair ①Includes the contents of minor repairs ； ②Check the vibration of the rotor and verify its static balance ； ③Check or correct the straightness of the shaft ； 　　④Replace the rolling bearings and lubricant ； ⑤Inspect the mechanical seal, and repair or replace the rotating and stationary seal rings ； ⑥Check and adjust the clearance between both ends of the impeller and the front and rear covers ； 　　⑦Verify the instrument. 　　Major repair 　①Includes the contents of medium repair ； ②Conduct inspections to assess the degree of wear and corrosion of various components, as well as any damage to the ceramic linings; inspect or replace these components as necessary ； 　　③Replace the impeller, shaft sleeve, and pump cover ； ④Adjust the levelness of the suction-type magnetic pump casing ； ⑤Inspect the motor ； ⑥Corrosion protection of the machine. 　　Maintenance methods and quality standards 　　① Housing and pump cover 　　The housing and pump cover must not have any cracks or large-scale pitting; the ceramic lining must not be damaged ； 　　If the cast iron pump cover and housing end faces are severely corroded or eroded, and the sealing requirements cannot be met, they should be discarded. If the lining of the ceramic pump cover is damaged, it can be repaired by replacing the lining. 　　②Spindle, impeller, and shaft sleeve a. The spindle should be free from defects such as corrosion or cracks ； The fit between the spindle and the rolling bearing is H7/js6 or H7/k6; the fit between the spindle and the impeller is H7/m6. The straightness of the spindle should be no more than 0.2~0.4 mm/m ； 　　b. Gaps between both ends of the impeller and the front and rear covers ； The blades of the impeller should be free of burrs and cracks; it should be replaced if the impeller is severely corroded or if the blade thickness is reduced by half ； The coaxiality between the outer circumference of the impeller and the shaft hole shall not exceed 0.06 mm ； If necessary, the impeller should be subjected to a balancing test. After the impeller is assembled with the shaft of the self-controlled self-priming pump, the circular runout of its end face should not exceed 0.10 mm ； 　　c. The shaft sleeve and the shaft must not be made of the same material to avoid seizure ； The perpendicularity of the bushing end face to the axis shall not exceed 0.01 mm ； The surface roughness of the contact surface between the bushing and the shaft shall not exceed 1.6 pm, with an H7/h6 fit being used. 　　③Packing seal: The end face of the packing gland should be parallel to the end face of the packing box, and the tightness of all tightening bolts should be consistent to avoid uneven pressure ； 　　The depth to which the gland is pressed into the packing box is generally equal to the height of one layer of packing, but it must not be less than 5 mm. The cuts in the packing should be parallel, neat, and not loose; the cut angles should be between 30° and 45°, and when installing the packing, the joints should be offset by 120°. 　　④Mechanical seal: The surfaces of the rotating and stationary rings must be of high quality; there should be no defects such as cracks, scratches, or radial imperfections ； 　　All seals must be in good condition, and the rubber sealing rings should be replaced each time they are removed ； 　　The spring performs well with no noticeable deformation. 　　⑤Rolling bearings: The rollers of rolling bearings as well as the surfaces of their raceways should be free of pits and spots; the contact surfaces must be smooth, and there should be no abnormal noises during rotation ； 　　The fit between the outer ring of the rolling bearing and the bearing housing should be H7/h6; when installing the bearings, the rear bearing should be fixed, while the front bearing (on the side of the motor) should have an axial clearance of 0.20~0.30 mm ； 　　When installing bearings hot, immerse them in an oil bath at 100–120°C for 10–15 minutes, or use an electric heater for heating; direct heating with a flame is strictly prohibited. 　　⑥Elastic coupling: The elastic coupling and the shaft are matched using the H7/js6 or H7/k6 fit ； ’ 　　The radial runout of the two-half coupling should not exceed 0.07–0.09 mm; the alignment deviation between the two shafts in an elastic sleeve pin coupling, as well as the end-face clearance of the coupling, must comply with the specified standards.