Radial clearance of the stuffing box and seals
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This post was last edited by yxmqh on 2009-11-3 19:15. What should be the radial clearance between the filler box and the seals in millimeters? We have sizes of 5mm and 10mm available here. Is there any special impact on the gap size?
I just replaced the seals on two reciprocating compressors. I haven’t heard anything regarding the radial clearance of the seal rings (3/6 lobes); generally, the axial clearance is around 0.2 mm. As long as the seals are properly sealed, the (3/6 lobed) rings can still move. Sometimes I check the drawings for details
The radial gap had better not be too large; I think the smaller it is, the better. If there is a gap, leakage is possible!
The radial clearance has little to do with the smooth operation of the compressor, and no specific requirements exist for it.
No strict requirements are generally imposed on the radial clearance of seals, as long as they do not get stuck after expansion. Our company’s version is about 8 millimeters, while the radial width of the sealing ring is generally 10 millimeters. If a flow restrictor ring is installed, the requirements for the radial clearance become more stringent; the clearance between the flow restrictor ring and the piston rod must be greater than the clearance between the packing box and the outer diameter of the flow restrictor ring, in order to prevent wear on the piston rod.
1# kming121 Are you referring to the radial clearance of the piston compressor packing box and seals? If radial and tangential rings are used, the size of the radial clearance has little impact, but a greater axial clearance is required; this axial clearance must ensure that the sealing element can still move freely even after heating and expansion, without getting stuck.
The radial clearance is adjusted manually, and the value used for adjustment varies depending on the speed of rotation and the operating pressure – it is not fixed. There are also two types of packing: internal flushing type and external flushing type, each requiring a different adjustment of the clearance. The basic principle is that the packing should not be compressed too tightly; manual turning of the shaft serves as a reference value in this regard. However, it also shouldn’t be too loose, as this will increase leakage.