Question

How to find isolation parctically in direction coupler?

Answer 1

Maintenance procedures conducted on pipelines often
require isolation of a section of the line. Valve replacement, tie ins,
pipe replacement are a few examples of procedures which normally
require the pipeline to be taken out of service and drained down, or
solid material stops intrusively applied to the pipeline.
Pipeline isolation tools have been available and applied for
many years; these tools required pressure differential or tethered
control to activate and deactivate the isolating mechanism. While
these tools were applied with success, there was no way to accurately
monitor this early generation of tool for performance and determine
with reliability whether the tool was properly set. These tools had the
capability of performing one task, once the tool had completed its
task, it was removed from the pipeline and readied for its next
application.
A new isolation tool has been developed and proven for
pipeline application and this paper will discuss the Multi-Set
Isolation Tool (Iso-Tool), its unique features, development and
applicatio

Answer 2

Answer:

Port 4 of the directional coupler is known as the isolated port. In an ideal directional coupler, no signal should appear at the isolated port, however practically, a small amount of power called back power is obtained at Port 4.