<p>The displacement technique as a method of leak detection without locating leak spots has been developed in the Laboratory of Diagnostic Methods at the Institute of Nuclear Chemistry and Technology in Warsaw. The principle of this radiotracer technique involves introducing a radioisotope tracer into a regulated object which is linked to a compensating tank and a container filled with the same tracer via a system of tubes. Once the test pressure in the measuring system is balanced, scintillation probes with collimators are positioned on a specific tube to detect tracer movement and identify leaks. Three detectors are positioned side by side with every two detectors being 2 meters apart from one another. A Kr-85 or methyl bromide labeled Br-82 bromine as radiotracer is used. At least 100 kBq is injected all at once, and the system is set to measure for 1 second. Specialized software computes the transit times between each detector, which are then converted to the flow rate parameter Q [dm³/h]. A leak is deemed present in the installation if the Q value exceeds 500 cm³/h. This method is included in the new ISO standard proposal. In this work, the principle of displacement technique will be presented. The method will be compared with other routinely used leak detection techniques. The advantages and limitations of this method will be highlighted. A case study of the measurements will be shown.</p>