Designing mechanical seals for sealing refrigerants and other low viscosity liquids has been a difficult problem for seal manufacturers for many years. However, mechanical seals with antimony impregnated, carbon-graphite primary rings and solid silicon carbide counter face rings could solve this problem. Low viscosity liquids such as Freon refrigerants, liquid oxygen, liquid carbon dioxide, propane, ethylene, and acetone are now being successfully sealed using mechanical seals with Metcar Grade M-444, antimony impregnated, carbon-graphite primary seal rings.
Highly polished
Low viscosity liquids are difficult for mechanical seals because the hydrodynamic film that they create between the two rubbing seal faces is extremely thin. In order for this extremely thin hydrodynamic film to lubricate the two sealing faces, the seal faces must stay highly polished and they must run in very close proximity to each other. The M-444 antimony impregnated, carbon-graphite material and the solid silicon carbide and antimony impregnated carbon-graphite can enables these two materials to run in the required close proximity. Ordinary mechanical seals with resin impregnated, carbon-graphite primary rings do not have the self-polishing characteristic or the dimensional stability that is required for sealing these low viscosity liquids.