DF-DGS6 Tandem seal
with intermedia labyrinth

1 Primary seal face with DF-coating*, stationary
2 Primary seat with DF-coating*, rotating
3 Thrust ring
4 Spring
5 Shaft sleeve and seat retainer
6 Intermediate sleeve
7 Housing (adapted in size to the installation space)
8 "Adjustable" nut for axial misalignment
9 Split ring
10 Clamping ring
11 Cover
12 Process side labyrinth
GBI Gas Buffer Inlet
GBO Gas Buffer Outlet
D Drain
* Optional: secondary seal face and seat also with DF-coating.



  • DiamondFace bonded primary seal faces
  • Safe cupped retainer for rotating ring
  • Bi-directional
  • Ready-to-fit cartridge unit
  • Single, double, tandem and tandem seal with intermediate labyrinth arrangement available
  • An ideal solution for Ethane, CO2 and many other low vapor margin applications
  • This type of seals can handle both liquid and gaseous phases during the operation of the pump


  • Significantly lower leakage rate compared to competition
  • Longer life span
  • Wear and contact free operation
  • Self-cleaning 3-D gas grooves
  • High gas film stiffness
  • Proven, reliable and economical solution
  • Can be adjusted even to extreme narrow installation space - retrofits are easy to implement

Operating range

Shaft diameter:
D = 32 … 154 mm (1.26" … 6.06")
Pressure (static and dynamic): p = 0 … 120 bar (1,450 PSI)
with PTFE option: 0 ... 250 bar (3,625 PSI)
t = -20 °C … +150 °C (-4 °F … +302 °F)
with PTFE option: -100 °C ... +200 °C (-148 °F ... +392 °F)
Sliding velocity:
vg = 0.6 … 140 m/s (2 … 459 ft/s)

For applications outside the operating range mentioned, please inquire.


Primary seat and seal face: Silicon carbide with DiamondFace bonding
Secondary seat and seal face: Silicon carbide with DLC coating. Optional also with DF-coating
Secondary seals: FKM, PTFE (DF-PDGS6) or other elastomers, depending on product gas composition
Metal parts: 1.4006 (410) and other stainless steels

Standards and approvals

  • NACE


Dimensions on request.

Recommended piping plans

Product variants


Version for high pressure and both low and high temperature applications. With U-cups and special dynamic sealing elements. Secondary seals made of PTFE.
DF-DGS6 Tandem seal