what is mean by loop checking?

Answer Posted / mathan

loop checking means ,after installation of instruments we
must check full loop(instrument-junction box-control room)
to ensure that whether the instruments are working properly
or not, and whether is it passing the signal or not,whether
is it receiving the signal or not. before we start the
plant we need to check loop..
during the loop check we give some known input
and check the corresponding output at other side(control
room)..if the output is corresponding to input, the loop is
ok..if not means, something fault inbetween the loop.
for example.if you want to check ON/OFF control
valve,during the loop check,when you give 24v dc from
control room ,the valve must open fully, and when you give
0v dc the valve must close.

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