Leak detection and prevention
There are many methods used to detect leaks on tanks or pipes but only some are able to prevent environmental contamination.
The best way to prevent and detect leaks is by using double walled tanks and pipes, and constantly monitoring the integrity of the interstitial space. In 1956 German law claimed that groundwater had to be protected against environmental pollution. Leak detection systems for singlewalled tanks have been developed and used up to the 1980s. Finding out that these systems still have some weak points an upgrade in the law in the 1970s required doublewalled tanks and more advanced leak detection systems.
Within a short time there was a new standard, requiring and defining overpressure, underpressure and liquid leak detection systems. These standards have been taken over by other countries like Switzerland and Austria. Within the last 15 years requirements for double walled tanks and pipes equipped with under- or overpressure or liquid leak detection system spread throughout Europe and the world.
Liquid leak detection systems work by filling the interstitial space with leak detection liquid and locating a header tank with a sensor on top of the tank. In case of a leak, leak detection liquid will enter the inner tank or the environment, causing a liquid level drop in the header tank which is recognised by the sensor.
It is necessary to place the header tank higher than the ground water table, which might cause additional installation costs.
Part of the functioning of the liquid system is that the stored product and/or the environment will be contaminated with the leak detection liquid in case of a leak.
In many European countries the liquid systems are not allowed to be installed anymore as the used liquid itself is defined to be a water endangering product such as ethylenglykol with fungicide additives.
Underpressure leak detection systems (also called the vacuum systems) realise the following monitoring principle: The pump in the leak detector creates an operational underpressure in the interstitial space. The operational and the alarm underpressure are adjusted so they are at a higher pressure than that of the stored product. The underpressure is high enough to suck product or groundwater into the interstitial space and up into the liquid stop valve, which is installed on top of the tank in the suction line of the leak detector.
