The Linapulse is a portable resistivity system used to detect holes or defects in plastic membranes. A constant voltage power source is connected between two steel electrodes, one located in the ground surrounding the membrane, the other located in the material immediatly above the membrane. The linear is an electrical insulator, hence, when there are no defects within the linear, an electrical current has no way of flowing through it. However, if a hole is present, current flow is possible and an increase in electrical potential will be observed in the vicinity of the defect.

Measurements are made by observing the potential difference between two non polarising electrodes, one of which is placed at a fixed location in the material above the linear while the other is moved around the test area by an operator who also records data displayed on a portable voltmeter.

Holes as small as 2mm in diameter have been detected and located to within 5cm using the Linapulse, as illustrated in the following example, in which, for test purposes, a 2mm hole was deliberately made in a liner to assess the systems's sessitivity. Another unexpectd hole was found to exist, the result of a knife cut, approximately 10mm in length.