In the interstitial space of a double walled tank an overpressure is created using dry air or inert gas.
This overpressure is adjusted at a level, that an untightness or a leak will result into a pressure drop.
Minor pressure changes can be adjusted by integrated pumps within a defined limit. By that unavoidable, small, installation caused untightnesses are compensated.

Bigger pressure changes, caused by leaks lead to obvious pressure changes and to the release of the optical and acoustical alarm.

SGB leak detectors are in accordance with class I of the European Standard. They are constructed inherently safe and monitor permanent both walls of a double walled tank or pipe.

Calculation of the alarm pressure

The alarm overpressure value must be minimum 30 mbar higher than the static pressure of the stored product to the bottom of  the tank. 


With over pressure leak detection systems, stored product or vapors of the stored product will not  enter the interstitial space, the connection linings and the leak detector.

All the equipment which can get into contact with the stored product must be chemical resistant to the product and to the vapors. (E.g. Connection lines in the manhole chamber)

In case of permeation of hazardous materials through the inner wall into the interstitial space the equipment must be explosion proof. (E.g. use of an inert gas leak detection system on a GRP-tank.)

3-D Animation

Monitoring of several horizontal underground tanks with overpressure (air)