51. What are the effective ways to increase labyrinth seal medium resistance? Answer: 1) reduce the gap, 2) to strengthen the vortex and 3) increase the sealing teeth, 4) try to make the turbulence kinetic energy into heat energy
52. What is the principle of floating ring seal? Answer: floating ring seal in shaft and in the narrow space between the floating ring of throttling action as the foundation, and the pressure of a gas injection is higher than in the gap of seal oil, in order to achieve the purpose of the sealed gas.
53. The causes of the floating ring seal leakage quantity increase? Answer: 1) floating ring for long-term use, normal wear and tear, make clearance increases; 2) floating ring hole bushing rough surface, low precision, short time wear make clearance increases; 3) improper assembly deflection, the loss in the attachment, make the oil flow from other clearance, is leaking;
54. What is the function of oil block? How to conduct oil baffle clearance measurement and adjustment? Answer: 1) the role of oil block is to prevent the bearing lubricating oil flows along the axis neck to bearing external oil block installation location has two kinds: one is on the bearing seat, the other is on the bearing shell; 2) oil gear clearance when oil block disintegration or assembly available measurement. For bearing shell can be clearance in oil, in the face of the oil on the bearing clearance is strict, generally require lower 0.05 0.10 mm, both sides in the 0.10 0.20 mm, upper 0.20 0.25 mm.
55. What are the influencing factors of labyrinth seal? Answer: 1) the radial clearance is too large, or a new replacement air seal ring gap is too small; 2) seal or air seal ring, the dull, worn between tooth or heated after long-term wear deformation, damage and cannot use; 3) after using for a long time, the spring slacken, deformation, quickly sealing ring can not reach the designated position, after operation, precipitation accumulation of dust, dirt, is sealing medium pressure is lower than the working medium pressure and pressure instability, etc.
56. What are common types of dynamic seal? Answer: the cup seal, flange seal and spiral seal, pneumatic seal and seal hydraulic seal, centrifugal, packing seal and labyrinth seal, mechanical seal, etc.
57. What are the main factors influencing the sealing? Answer: 1) the seal itself quality, 2) process operating conditions, and 3) assembly precision, and 4) the host itself precision, 5) seal auxiliary system
58. The mechanical seal is made up of which a few parts? A: by static mechanical seal ring, ring, compensation of buffering mechanism, auxiliary seal ring and transmission mechanism. Static ring and ring end face perpendicular to the axis of the pump and fit each other, constitute a rotating seal face. Static ring and gland, all carried out with auxiliary seal ring seal ring on the shaft, to compensate for buffering mechanism drive ring along the axial movement, stay ring and static ring end face, and the wear of sealing ring end face to compensate.
59. What are the characteristics of the mechanical seal? Answer: 1) good sealing performance, leakage of mechanical seals generally 0.01 to 5 ml/h, according to the special requirements, with special design, manufacture of mechanical seal leakage of only 0.01 ml/h, and even smaller, and the packing seal leakage for 3-80 - ml/h (according to the relevant provisions of the our country, when the diameter of axle is not greater than 50 mm Φ less than or equal to 3 ml/h, when the diameter of axle is Φ 50 mm less than or equal to 5 ml/h); 2) long service life, general in more than 8000 h; 3) the friction power is small, only 20% of the packing seal - 30%; 4) there is no relative movement between the shaft and shaft sleeve and seals, won't produce friction, shaft and shaft sleeve lifespan is longer than the other; 5) sealing surface is perpendicular to the axis of the pump mechanical seal, seal pump shaft vibration generated displacement at any time, so the vibration in a certain range, can still maintain good sealing performance; 6) mechanical seal on the role of sealing liquid pressure and spring force, keep the static/dynamic ring sealing surface, and rely on the spring force to compensate for wear, so once the deployment of appropriate, in the operation of the pump in general do not need to change often, easy to use, small maintenance workload; 7) with wider range of operating conditions and can be used for high temperature, low temperature, high pressure, high speed and strong corrosion conditions; 8) troubleshooting and parts replacement is not convenient, can only be for maintenance after parking; 9) complex structure, high assembly precision, assembly and installation has certain technical requirements; 10) manufacturing high price
60. What are the main characteristic parameters of mechanical seal? Answer: 1) the diameter of axle: pump mechanical seal trunnion area generally is 6-200 - mm, special is 400 mm, the diameter of axle pump usually in strength requirement by the rounded or use collar modulation to conform to the mechanical seal standard diameter of axle; 2) speed: generally the same as the pump speed, general of centrifugal pump rotating speed is less than or equal to 3000 r/min. High speed centrifugal pump is less than or equal to 8000 r/min, special pump is less than or equal to 4000 r/min; 3) sealing surface average peripheral velocity: refers to the seals peripheral velocity of average diameter. Sealing surface average velocity, the sealing surface (i.e., friction pair) of fever and wear. General sealing discharge peripheral velocity less than or equal to 30 m/s; Application of peripheral velocity of the static type mechanical seal spring less than or equal to 100 m/s; Special can amount to less than or equal to 150 m/s; 4) end face specific pressure, face pressure Pc is on the sealing surface contact pressure (MPa). The end face seal face specific pressure should be controlled in a reasonable scope, starts to reduce the sealing performance, heat and wear will aggravate the sealing cover. Pumps with mechanical seal reasonable face specific pressure value: built-in type mechanical seal, generally take Pc = 0.3 to 0.6 MPa; Mounted outside, take the Pc = 0.15-0.15 MPa. Better lubricity when face specific pressure can be appropriately increased, the high viscosity of liquid film increases end face specific pressure, good Pc = 0.5 0.7 MPa fluid of low volatile, lubricity should take smaller end face specific pressure, good Pc = 0.3-0.3 MPa.
61. The mechanical seal assembly of inspection before what content? Answer: 1) general check: check a main components of the model, specification, performance, dimension, and presence of gap, such as some pit, deformation and crack damage. 2) check: dynamic and static ring end face to bright and clean bright, sealing side damage, some pits, grooves, scratches and other defects. Of graphite ring, also didn't check whether there is a crack.
62. How do I check my face parallelism, perpendicularity and surface roughness? Answer: 1) face flatness, the liquid medium is 0.0006-0.0009 mm, the gas phase medium of 0.0001-0.0004 mm; 2) the tolerance of balance: sealed end face seal ring contact surface parallel deviation, general ring is less than or equal to 0.04 mm. Set ring (ceramic ring, tungsten carbide ring) on both ends of the parallel degree of deviation should be less than or equal to 0.03 mm; 3) the perpendicularity tolerance; On the face seal ring installation place outside diameter of the center line of the vertical deviation, the diameter should be less than or equal to 0.03 mm; 4) surface roughness: seal face hard material (get) using the method of removing material dark glossy surface (grinding), soft materials (get) using the method of removing material invisible processing traces, the distinguishing processing direction (grinding, fine cars), contact with the auxiliary seal ring for invisible (get) using the method of removing material processing, the distinguishing processing direction (grinding, fine car), the rest to (get) using the method of removing material micro see mark (knife heave, fine car).
63. The mechanical seal auxiliary seal ring to check what are the requirements? Answer: 1) the auxiliary seal surface smooth level off, can not have bubbles, cracks, defects such as gap; End face size uniform; "O" ring of burrs and best working face into a 45 degree Angle; 2) the hardness of auxiliary seal ring to choose according to pressure, sealing pressure is higher, the hardness is higher; Sealing pressure lower, lower hardness. Auxiliary seal commonly used synthetic rubber; 3) seal "o" ring, cylinder diameter should be lower than the outer diameter of the seal point 0.5 1 mm. Ring the "o" ring diameter is small, quiet ring of "o" ring diameter is smaller than the static ring diameter; 4) the amount of compression of auxiliary seal to fit,, large amount of compression of the sealing effect is good, but the friction resistance is big, assembly difficulty, swimming in compensation ability is poor. Amount of compression is too small, small friction resistance, assembly easy but poor sealing effect. Mechanical seal "o" ring, for static ring are cylinder seal, the compression quantity about cross sectional smooth diameter of 8% 23%. Small diameter, take some percentage; Large diameter, take a smaller percentage. 5) the amount of compression "o" ring to consider the other functions such as the static ring without stop pin, static ring "o" ring plays a dual role of sealing and anti-rotating, "o" ring compression quantity is bigger, in order to avoid static ring rotation, seal failure. "O" ring ring, on the premise of guarantee the sealing effect, compression measuring, in order to avoid large amount of compression, resistance is not floating compensation.
64. The mechanical seal spring check what all does that include? Answer: spring check include: the total number of laps, effective and free height, the axis of the end face is vertical, spring handedness. But spring must be checked to the spring don't need to check to more. Freedom of new spring to check its original height, height measurement, and compared with original records, the residual deformation is too large to replace. After the old spring clean, to measure the elastic, elastic 20% less to replace. More spring mechanical seal, the spring free height difference should not be less than 0.5 mm.
65. The mechanical seal before installation check what are the requirements for shaft and shaft sleeve? Answer: 1) check the shaft or shaft sleeve with the size, surface roughness, chamfering, shaft axial momentum and radial runout, with sleeves, shaft and shaft sleeve should be checked for fit clearance. Installation of mechanical seal diameter of axle (or bush) below the surface roughness should be 1.6, axial amount shall not be greater than 0.25 mm. Axial axial channeling, shaft sleeve shall not allow the shaft or shaft sleeve of the radial circular runout, as shown in figure:
2) check the shaft and bushing wear. Because the mechanical vibration and dynamic compensation of the floating ring, shaft and shaft sleeve may be "o" ring wear, wear, if any, should make the repair or replacement light; 3) the shaft sleeve, collar should be in good condition
66. The seals or sealed box inspection content have? A: contact with static seal surface roughness is 1.6, after assembling the static ring, face round beating shall not be greater than 0.06 mm. The seals or seal chamber should be no burr, chamfering radius is too enough, smoothly. The seals or seal chamber diameter size should comply with the requirements.
67. What is the "six" content of pump inspection tour? Answer: the route, a person, time, dot, to determine responsibility, request to check.
68. The chemical pump Jia Xiu general maintenance types? A: there are three main forms: 1) maintenance, 2) the scheduled maintenance, 3) scheduled maintenance.
69. The matters needing attention of auxiliary seal ring assembly? Answer: 1) rubber soaking auxiliary seal ring can't use gasoline, kerosene catharsis, in order to avoid large deformation, premature aging; 2) "o" ring is installed on the static ring components, smoothly, don't distortion, the cross is the burrs is in a state of freedom; 3) propulsion components, to prevent the "o" ring damage. Main damage form are falling, fissure, bruised, edge and distortion.
70. The mechanical seal "o" ring crack reason have? Answer: the shaft surface rough or burr; The old shaft or sleeve is fastening screw head injury, not smooth before assembly; Keyway and stop pin groove edge not appropriate dressing.
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