‘Leak detection systems do not work and only generate false alarms’ is still heard quite frequently. This is unfortunate since just the opposite is true. Modern state-of-the-art systems are highly reliable while permitting sensitive leak detection and accurate leak localisation.
This paper starts with the basics, why install a leak detection system and how to choose a system that suits your application. The focus is made on the Human Factor. What is important for the people working with this system? For example; No false alarms might be preferred above looking for the ultimate sensitivity and thereby increasing the opportunity for false alarms.

Typical leak detection specifications, such as sensitivity and accuracy, are also taken into consideration. Are these specifications relevant to real life situations or do they only refer to fully stationary pipeline conditions that are only encountered in theory.
In practice pipelines always exhibit (small) transients. In addition, the accuracy of the installed instrumentation, data refresh rates, time allowed to detect a leak, position and number of field instrumentation and many other factors influence the performance of a leak detection system. When selecting a system, field test results from similar applications may form the best reference.    
The paper describes the E-RTTM technique that KROHNE uses for PipePatrol, their Leak Detection and Localisation System. The paper explains, without going into mathematical details, how the model works and why KROHNE has choses this model as the basis for their system. Today E-RTTM based systems like PipePatrol can boast of many proven applications on gas, lpg, crude oil and refined product pipelines. Field test results from an ethylene sub-critical gas pipeline are described to demonstrate that modern leak detection systems are more than a theoretical exercise; they do work and do this without false alarms.