| 摘要 |
A defect in a horizontal or vertical seam at the edge of a roof membrane is detected by applying a DC voltage between the roof deck a probe in the form of a flexible wetted sponge and wiping the sponge probe over the seams. The current to the probe is detected and indicated to the operator so that t he operator may determine a maximum current at the defect. The receiver provide s an audible signal emitter to the operator and includes a calibration circuit arranged to automatically maintain, despite changes in voltage applied between the roof deck and the peripheral conductor, a "0" set calibration point so as to indicate at the calibration point when zero difference in voltage is detected. Conductors ca n be applied to the membrane to define an area to be tested within the conductors . |
