Sealing of Rotating Shafts

Sealing tlie Centi-ifiig Chemical Pump Altliougb detailed treatment of. shaft seals is presented iu tbe subsection Sealing of Rotating Shafts, it is appropiiate to mention here tlie special problems... 

As a result of that operation, uncontrollable accumulation of significant masses of lead oxides in the primary circuit h pened, they could have formed when the pipelines of the primary circuit gas system, which were necessary for its repair, were depressurized, and thus the air penetrated into the primary circuit. Besides that, the primary circuit was contaminated by products of oil pyrolysis, which was the working medium for seals of rotational shafts of pumps that provided the gas leak prooihess of the primary circuit. Masses of oil were spilled into the primary circuit because the oil seals had not been reliable enough. 

These can occur from leaking flanged joints, seals of rotating shafts, glands of control valves, and nozzles for insertion of thermocouples or for cotmeclions to flow sensors. 

Contact seals of rotating shafts. G.A.Golubyev, G.M.Kukin, G.Ye.Lazarev, Moscow, Mashinostroyeniye, 1976, -264 p ... 

A substantially new and critical feature in bottom-entering agitators is the sealing of the shaft double mechanical seals are used here. On modem designs, they are provided with additional standstill seals for emergencies. The standstill seal allows the mechanical seal to be replaced while the reactor is full and under pressure. In a number of polymerizations, particularly in vinyl-chloride polymerization, the rotating elements must be protected by additional water flushing (4) other-... 

The entrainment of gas in the liquid is undesirable in most mixing operations. In addition, the bearings and seals of stirrer shaft are subjected to exceptionally strong mechanical stress, due to the inhomogeneous gas/liquid mixture and the fact that the stirrer partly rotates in air and therefore the liquid bearing is absent. It is therefore of practical interest to know how a stirrer can be operated in an unbaffied vessel in such a way that vortex formation can be tolerated. 

Where conventional lubricants cannot be applied for reasons of incompatibility with the working fluid at operational conditions of temperature and pressure, it has been found necessary to develop alternative methods, and dry lubrication" using solid lubricants has been adopted for cryogenic applications. Components that lend themselves to.this treatment are bearings and seals for rotating shafts and pistons and cylinders in reciprocating systems. 

Mechanical Face Seals This type of seal forms a running seal between flat precision-finished surfaces. It is an excellent seal against leakages. The seahng surfaces are planes perpendicular to the rotating shaft, and the forces that hold the contact faces are parallel to the shaft axis. For a seal to function properly, there are four sealing points ... 

With close-clearance seals it is important that the shaft be closely maintained in its rotating position flexible shaft design (operation above the first lateral critical) is usually not acceptable. Bearings that maintain the closest alignment of the shaft are obviously the best for such applications and, for this purpose, close-clearance journal-type bearings are used. 

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