1Seal face, atmosphere side
2Seal face, product side
6, 7, 13, 14, 15O-Ring
11Seat, product side
12Seat, atmosphere side
Flange connections acc. to DIN 28137 T2
for nominal diameters 125 ... 161.



  • For top entry drives
  • For glass-lined vessels
  • Double seal
  • Unbalanced
  • Independent of direction of rotation
  • Multiple springs rotating
  • Liquid-lubricated
  • Cartridge unit


  • Ready-to-fit and factory-tested unit
  • Available with or without bearing
  • Suitable for standardizations
  • Seal can be applied at higher pressure and rotating speed than specified by DIN
  • Self-closing on product side
  • The seal can be lifted off the glass-lined flange as a complete cartridge. The sensitive glass lined basic flange remains mounted on the vessel.
  • ATEX certification on request

Operating range

Shaft diameter:
d1 = 40 ... 160 mm (1.57" ... 6.30")
p1 = vacuum ... 16 bar (232 PSI),
p3 = max. 18 bar (261 PSI)
t1 = -40 °C ... +200 (250*) °C
(-40 °F ... +392 (482*) °F)
Sliding velocity:
vg = 0 ... 5 m/s (0 ... 16 ft/s)

For applications beyond this range, please inquire.

* with cooling flange

! It should be noted that the extremal values of each operating parameter cannot be applied at the same time because of their interaction.


Seal faces: Carbon graphite or Silicon carbide, FDA conform
Seats: Silicon carbide, FDA conform
Secondary seals and metallic parts acc. to application and customers' requirement.

Standards and approvals

  • FDA
  • ATEX
  • DIN 28138 (mechanical seals for agitator shafts)
  • DIN 28136 T3 (for glass-lined vessels)
  • DIN 28137 T2 (flange connection for glass-lined vessels)
  • DIN 28159 (shaft end for glass-lined vessels)


  • Cooling resp. heating flange
  • Leakage drain resp. flush

Recommended piping plans

Product variants

Double seal

Double seal with integrated floating bearing.

Double seal without/with floating bearing
for PN 25 (Special seal on request.)

These seals are designed to be self-closing on the product side, i.e. they will remain closed even with pressure variations or a pressure reversal. Operation is possible with buffer fluid (p1max = 6 bar (87 PSI)) or pressurized with barrier fluid as double seal.
All types of the M461 range available for unstepped shafts (all diameters). Seal identification: M491... Customized design or e.g. different drives (torque transmissions) are available.