A fiber optic cable suitable for blowing into and through ducts containing
pressurized gas, such as natural gas, has the fibers therein arranged in
arrays that form longitudinally extending vents. The vents are blocked
from transmission of any gas by each being filled with a compliant member
which assumes the cross-sectional shape of the vents thereby blocking it.
In a second embodiment of the invention, the first and third ferrules are
fixed within the housing with their offset bores in alignment. A second
ferrule is interposed between the first and third ferrules and is mounted
in a rotatable member for misaligning the bore in the second ferrule with
the bores in the first and third ferrule to produce attenuation of a
signal passing through the ferrules by misaligning the fibers contained in
the bores.
