Patent ID: 8213756

Claim:
A fiber optic cable comprising: an outer protective tube; a fiber optic tube having a plurality of optical fibers contained therein; at least one annulus disposed between the outer protective tube and the fiber optic tube; a first path extending through the length of the fiber optic cable and which provides a first channel for a purge gas to flow in a first direction of the fiber optic cable, wherein the purge gas removes a second gas from the fiber optic cable; a second path extending through the length of the fiber optic cable and which provides a second channel for the purge gas to flow in a second direction of the fiber optic cable, opposite the first direction; and a means for connecting the first path to the second path, wherein the purge gas is injected into the fiber optic cable through the first path and is returned through the second path via the means for connecting the first path to the second path, and the returned purge gas is monitored by a monitoring unit for the second gas to determine whether the second gas is still present in the plurality of optical fibers, and if the second gas is still present, continuing the injection of the purge gas, and if the second gas is not present, ceasing the injection of the purge gas.