Item Description
1 Seal face
2 Stationary seat
3 Bellows
3a Gasket
4 Spring
5 Driver
5a Drive collar



  • Rubber bellows mechanical seal
  • Unbalanced
  • Single spring
  • Independent of direction of rotation


The main design features of the BT-PNT are the metal joint torque transmission together with the rubber bellows. This prevents torsional effects on the bellows. The shaft is protected across the entire seal length. Easy to assemble, the BT-PNT guarantees a long service life due to good product turbulence.

Operating range

Shaft diameter: d1 = 15 mm, 5/8”, 3/4”, 1"
Pressure: p1*= 12 bar (174 PSI)
t* = -20 °C … +120 °C (-4 °F … +248 °F)
Sliding velocity: vg = 10 m/s (33 ft/s)

* Dependent on medium, size and material


Seal face:
Carbon graphite resin impregnated (B), Carbon graphite, full carbon (B3), Silicon carbide (Q1)
Aluminium oxide (V), Silicon carbide (Q1)
Elastomers: NBR (P), EPDM (E), FKM (V)
Metal parts: CrNi steel 1.4301 (F), CrNiMo steel 1.4401 (G)

Standards and approvals

  • KTW
  • W270
  • ACS
  • WRAS
  • NSF
  • FDA
  • DM 174/04