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ASF Leak Detector Type D25 - Pressure Principle

Available as 2/4 bar Version (pressureless pipeline), 2/6 bar Version, and 11/15 bar Version


  • The leak detector is used to monitor double-walled underground piping.
  • For monitoring of water-polluting liquids and/or flammable liquids with a flash point < 55°C.
  • The max. operating pressure allowed is 16 bar.
  • The alarm switching value must be min. 1 bar above the operating pressure of the inner tube.
  • When monitoring depressurized piping the pressure needs to be around 4 bar.
  • Also other monitoring pressures than the specified default values can be set (for details please see the technical description).
  • The leak detector can be connected to multiple pipelines by using an appropriate manifold.

The leak detector must be mounted outside the hazardous area (ex-zone)!


Product images

D25_produktOperating Conditions

  • The interstitial space of the double-walled piping must be suitable for connecting the leak detector.
  • The double-walled pipeline must have the General Building Inspection Certificate (formerly Prüfzeugnis) or an admission of an other certified office.



Mounting kits (MBS), protective casing and manifolds.



  • Leak detector according to the pressure principle.
  • The interstitial space is filled once with inert gas - nitrogen (N2). Thereafter, the supply bottle, or the connection to the supply line can be removed.
  • The required monitoring pressure remains in the interstitial space without any refills necessary, if the piping work is done carefully.
  • The alarm switching value must be set min. 1 bar above the max. operating pressure chosen.


Standard Switching Values:

Permissible operating pressure: Po

Po in bar 0 1 10 16
Alarm OFF PAA = bar 4 6 15 21
Alarm ON PAE = bar 2 2 11 17

For further data please see the data sheet of the D25 leak detector.


Mounting Examples

Please click on the picture for a larger view!




ASF pdfInstallation and Operation Manual D25

ASF pdfData Sheet D25

ASF pdfD25 Accessories & Assembly Kits