Item Designation
1 Seal face
5 Seat
13 Sleeve
16 Housing
18 Pin
37 Locking fixture
2, 12, 15, 22, 23, 24, 25 O-Ring
43 Plug

LP-D-UP Dual seal
Ready-fitted for Ahlstar UP A MS21 range of pumps, bearing unit A1-A6



  • Integrated seal for Sulzer A pumps
  • Dual seal, balanced
  • Semi cartridge unit
  • Independent of direction of rotation
  • Double pressure balanced
  • Internal barrier fluid circulation
  • Static springs on both sides
  • No dynamic O-Ring on shaft
  • Rugged design
  • Shrink-fitted seal faces
  • Seal faces have a large clearance to the shaft
  • Wear part cost minimized
  • Optimized design for Non-Flow use


  • Individually integrated to equipment for the best sealing result
  • Straightforward and easy installation
  • Static springs on both face sides reduces influence of misalignment
  • No damage of the shaft by dynamically loaded O-Rings
  • Extended service life due to rugged design
  • No brittle parts in contact with torque transmission pins
  • Seal faces protected by strong steel parts and a large radial clearance

Operating range

t = -20 °C ... +140 °C (-4 °F ... +284 °F)
(180 °C (356 °F) with Kalrez® elastomers)
p1 ... 25 bar (363 PSI), p3 <12 bar (174 PSI)
Sliding velocity: vg ... 20 m/s (66 ft/s)
Stock content: <8 %

Non-flow operation:
t = +5 °C ... +100 °C (+41 °F ... +212 °F)
p1 max. 10 bar (145 PSI), p3 > p1
Sliding velocity: vg <10 m/s (33 ft/s)


Seal face: Silicon carbide (Q12), Carbon (A)
Secondary seals: FKM (V), EPDM (E), FFKM (K)
Metal parts: CrNiMo steel (G),
Grade 5A (4T), SMO 654 (4U)


  • Double, quench and single seals have the same wear parts on the prouduct side, reduces stock holding costs
  • The dual seal can also be used as single seal by removing the atmospheric seal parts
  • Can be used with pressurized buffer fluid or with quench

Product variants

Dual seal, adapted for Sulzer APP/APT pumps.

Dual, adapted for Sulzer SL Mixers.

Further designs
available to fit in numerous other equipment from notable manufacturers for the Pulp- and Paper Industry e.g., Metso conical refiners, Andritz pressure screens and stock pumps.

Similar products


  • Dry gas seal for multiphase pump applications
  • DiamondFace sliding surface technology
  • Ideal for applications with Ethane, CO2, and similar media with low vapor margins
  • Shrouded rotating ring
  • Bi-directional
  • Ready-to-fit cartridge unit
  • Single, double, tandem, and tandem with intermediate labyrinth available

DF-SA DiamondFace

  • Cartridge design
  • Single seal
  • Balanced
  • Integrated pumping device
  • Stationary spring loaded unit
  • Inserted seal ring
  • Rotating mating ring
    (DiamondFace coated)


  • Single seal
  • Balanced
  • Independent of direction of rotation
  • Multiple springs stationary
  • Seat rotating
  • Seat arranged directly behind the impeller
  • Spring protection sleeve
  • Variant with cylindrical spring and acc. EN 12756 (HRZ1) available
  • Variant as cartridge with/without guide sleeve for application with/without quench (HR2, HR3)
  • Dual seal as cartridge unit (HRKS-D) available

Inquire about individual solutions

We develop and produce customer-specific special and individual solutions for every application.

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