The FSI 3000 Series mechanical seal is a multiple spring design available in both balanced and unbalanced configurations. The basic 3B/3B-1 can be offered for single, dual, or tandem operation. Most 3000 Series mechanical seals are custom engineered designs due to operating conditions and / or equipment type.


  • Normally cartridge seal mounted for ease of installation and equipment accommodation
  • Can be used as either a rotating spring design or as a flexible stator design depending on operating parameters
  • Required seal face designs and balance ratios can be calculated to ensure optimum performance
  • Can be furnished with pumping ring or circulating shroud for API Plan 23 or 53 operation


  • Refinery & Petrochemical light hydrocarbon services
  • High pressure multistage pumps
  • Circ water & cooling water services
  • Boiler Feed pump applications
  • Specialty Equipment applications


  • Close clearance restriction bushings, floating throat bushings, and lip seals for use in conjunction with API Plans 21, 23, and 32.
  • A complete line of standard and custom designed seal reservoirs to support tandem and double seal operations per API Plans 52 and 53.
  • Specifically sized and selected heat ex-changers for proper seal cooling when using API Plans 21 and 23.
  • Custom engineered bearing isolating devices for specialty equipment applications.

mechanical_seals_3000_series_diagramOPERATING PARAMETERS:

  • Temperatures:  0°F to 500°F* (-20 C to 250 C)
  • Pressures:  Up to 1200 psi* (80 Bar)
  • Shaft Speeds:  Up to 4500 RPM*


  • Metal Components:  316 SS Standard (exotics upon request)
  • Seal Face Materials:  Carbon, Silicon Carbide, Tungsten Carbide
    Elastomers:  Fluoroelastomer, Perfluoroelastomer, Aflas, EPR/EPDM as standard o-ring materials. All other commercially available elastomers as specified.
  • Sizes:  Up to 6.00