Felt Seal is normally used with bearing housing of variety SN, PDN,  TVN, Flanged housing, SD500, SD600, SD30 series. For SDG type also  felt seal is used along with labyrinth seal.

 The felt is a simple and adequate seal with grease lubrication at  peripheral speeds up to 4 m/s. It can be used at temperatures of -40  to +100 degree C. Felt seal is contact seal rubbing on shaft surface. It  can also be used at higher speeds but a small gap will then generally  be formed between the felt and the shaft, so that the sealing action  becomes that of a non-rubbing gap- type seal.

 Plummer Block housing of series SNA, SNH and SNL are available with  split Felt Seals consisting of oiled felt incorporated in the two halves  of  an aluminum alloy ring. Such seals are designated as TC or TSNA  500C & TSNA 600C. There is an external groove in alloy ring halves  where O- section rubber cord is inserted while fitting the seal halves  into the bearing housing. The O-section cords provide an effective  contact between the housing and the alloy ring in addition to  preventing the ring rotation in the housing.

 Bearing Housings of series SNA 205 to SNA 218 , SNH 205 to SNH 218  and SNL 205 to SNL 218 can be supplied with felt seals which are  loose felt strips and which are fitted directly in housing grooves  (without alloy rings). Before fitting, the felt strips should be immersed  in hot oil for a few minutes. The maximum permissible misalignment  of the shaft is approx 0.5 degree. It is recommended that the surface  roughness of shaft should not exceed Ra = 3.2 micro.

 Generally felt seal is not suitable for oil lubrication in housing and  vertical mounting but suitable for axial shaft displacement. Felt seal  can be selected for external conditions with dust, sand, grit, sharp  objects, clippings, splinters and sunshine, but it is less suitable with  splashing fluids.