Abstract: An apparatus for detecting structural integrity and localizing leaks from fluid storage holding structures, such as fuel supply storage tanks and fluid carrying pipelines. The invention comprises at least one reference electrode or material and at least one sample collection container containing an absorbent/adsorbent material. The sample container is positionally moveable within at least one perforated pipe disposed below the fluid holding structure. Leaking substances from the holding structure flow into the perforated pipe, into the sample container, and are absorbed/adsorbed. By removing the sample container from the pipe, the quantity, quality and position of the leak is detected.

Abstract: A fluid detector that senses fluids, activates an alarm and preserves a sample of the fluid for laboratory or on-site testing. The fluid detector includes a first container having a sealable cap and a fluid-passing portion, a second container disposable within the first container for collecting and storing a sample of the fluid. The detector can contain a fluid-responsive material which undergoes a change upon contact with the fluid. The change in the fluid-responsive material causes the second container to be sealed. The second container can contain a fluid collector so that the fluid can be analyzed.