Function

An underpressure is created and maintained by the leak detector in the interstitial space.
In case of a gas leak, air or vapor are sucked into the interstitial space causing a underpressure decrease in the system.

Small leaks or untightnesses are compensated by the pressure pump. Relevant leaks can not by compensated due to the limited  pump volume flow. The underpressure continues to decrease.

When the alarm pressure is reached, the optical and acoustical alarm is triggered.

In case of a liquid leak, stored product or groundwater is sucked into the interstitial space. The underpressure decreases and the pump is switched on to reestablish the operational underpressure.

Within some time the stored product or the groundwater is sucked into the suction line of the leak detector and into the liquid stop valve. The liquid stop valve closes and disconnects the pump from the interstitial space. The pump is not any more able to produce underpressure in the interstitial space.

The underpressure still existing in the interstitial space and in the measuring line will decrease by more liquid sucked in. When the alarm pressure is reached the optical and acoustical is triggered.

In case of the alarm, the underpressure in the interstice is still high enough, that no stored product can enter the environment.

Calculation of the alarm pressure

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



For tanks with a suction line for the leak detector down to the deepest point of the interstitial space, the alarm pressure must be minimum 30 mbar.

 

Aspects to keep in mind:

 

With vacuum leak detection systems, stored product or vapors of the stored product can enter the interstitial space, the connection linings and the leak detector.

 

All the equipment must be chemical resistant to the product and to the vapors.


In case of hazardous atmospheres the leak detection system must be explosion proof.

3-D Animations

Monitoring of a double bottom of a flat bottom tank with vacuum
Monitoring of a horizontal tank with suction line to the deepest point of the interstice with vacuum
Monitoring of a horizontal tank with vacuum
Monitoring of a vertical tank with vacuum