Answer / 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.

Answer / selvakumar

Loop Checking means, First we want to check the continuity
of cable. Then whether 24 V DC or 4 - 20 mA DC is coming
from DCS or JB want to check. That is called loop Checking.

Answer / rovel delalamon

loopcheking, field to the control room.from instruments to ijb.formijb to mrashalling cabiet.,,check polarities,check the voltage suplly w/24v dc. chech also the possible leaks of the tube.and warm-up 5mins.prior to calibration.use HART COMMUNICATOR.highway addressable remote transducer.the one who configuer the input and output of the trnsmitter

Answer / shreeyash nandurkar

Loop Checking
Some think of loop checking as
a process to confirm that the
components of the loop are wired correctly and is typically
something
done prior to start-up. However,
due to factors described in the
introduction above, the loop check’s
scope has expanded to also include
tests to confirm that it is “operating as designed” and then
to ongoing
programs for benchmarking and monitoring performance. The block
diagram in Figure 1-5 illustrates the
components of this expanded loop
checking process.
This process starts when the instruments are received at the
plant site.
It continues through installation and
start-up and into the ongoing plant
operation. In addition, the control system should perform
the intended
function properly. This includes
verifying the transmitter’s process
variable (PV) for display to the operator, for use in the
control strategy,
and for historical trending. This verification testing prior
to start-up is
known as the factory acceptance test
(FAT) which, as an option, can be
duplicated at site with the actual hardware and software
installed, termed
site acceptance test (SAT). Further discussed in Chapter 2,
the FAT can be
performed prior to shipment of the
hardware or in parallel with the
hardware installation
at site if the overall start-up schedule is compressed.
Once the technician checks the control strategy to verify
that the
expected output to the final control element is produced,
the loop can then
be commissioned and start-up can proceed.
Finally, the loop check can include defining the loop
performance
benchmark and providing a method for monitoring the
performance over
time.

Answer / md mahtab khan

loop checking as a process to confirm that the
components of the loop are wired correctly and is typically something done prior to start-up.

Answer / rodel baluyot

LOOP CHECKING IS CHECKING 4 TO 20 MA OUTPUT FIELD AND CONTROL ROOOM

Answer / azarudeen

Loop checking is nothing but Checking continuity.

Answer / surya

I think loop checking is another way of calling "feedback"
...
m not sure abt it..

Why we use 250 ohm resistor in series with HART protocol communication?

13 Answers   Chemtrols, Instec, Sabic,

regarding level tx i would like to know how to select the range of the level transmitter in a closed drum(steam drum or deaerator)?

1 Answers  

PID controller is used for which type of compensation…… a) lead comp. b) lag com. c) lead lag com.

12 Answers   Engineers India Limited,

How to check electrical health of Vibration probe?

1 Answers   QAFCO,

why we use only 4-20 ma signal as AI and not 0-20 ma?

2 Answers   Honeywell, Oil and Gas Jobs,

what is function of ESD , and how is it work, explain with difination

1 Answers   Bapco Bahrain Petroleum Company, BMB,

what is the difference between Digital output DO signals /Commands for start/stop and Solenoid valves ??

1 Answers  

How a pH sensor & analyzer work at waste water treatment plant, whats the principle & science is beyond this,How pH sensor sence & convert signal & move toward analyzer & analyzer show reading in percent? also what is temperature compensate option in analyzer

1 Answers  

How to calibrate an pressure gauge with yantrika test bench?

0 Answers  

what is easiest way to read STL language in PLC?

0 Answers   LB Industries,

I am manjunath having exp in maintenance of chemical plants,know i want to do a design course INTOOLS,after doing design course can we get jobs in design field.sinve i dont have design exp..

0 Answers  

What is the constant voltage unit?

0 Answers