Answer / senthil

1.During commissioning, we ll do loop checks.it means from
field instrument( PT,TT,FT,LT or switches) the signal is
checked with the DCS.
for example : consider a PT,we ll simulate 4 to 20 mA in the
instrument and the same value should be shown in the DCS also.

2.there are two loops
open loop and closed loop
closed loop for controllers to control the process.for
example, antisurge control in Gas Compressor,Three element
control in Boiler

Answer / g.venkat

There are two loops
1. open loop
2.close loop


open loop using for monitoring and recording purpose

close loop using for controlling the fianal control element

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4 Answers   Honeywell,

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The DCS has the following signal type:

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HELLO FRENDS ,, I M IN THE MIDST OF TROUBLE .. JUST LITTLE HELP ME... SUPPOSE ,, I HAVE A CLOSE VESSELE TANK ( HEXANE MEDIA ) ,, I M USING ROSEMOUNT 2051 DPT FOR LEVEL APPLICATION .. ITS CALIBRATE RANGE IS.. . 0 TO 950 MMH20 ..I DID CALIBRATED DPT WITHOUT REMOVING IMPULSE LINE OF HIGH AND LOW TAPPING.. & WITHOUT DISTURB 3 WAY MANIFOLD..!!! BUT ,,, DURING CALIBRATION I SELECT RANGE BY HART LRV IS 900 MMH20 & URV IS 1300 MMH20 ,, BUT ,TANK LEVEL SOMETIMES 100 % AT 1100 MMH20 , SOMETIMES 1300 MMH20 ..IN THIS CONDITION .. WHOLE LOOP FAILED ,, MAIN THING IS THAT ,, HOW TO CUSTOME RANGE SELECT ?? AND IF I USED RANGE OVER THE ORIGINAL CALIBRATE RANGE ,,,THEN WHAT ERROR WILL BE COME ??? HOW TO ZERO CALIBRATION OF DPT... HOW TO ZERO TRIM BY MANIFOLD ?? AND FOR TANK LEVEL PURPOSE ... WHICH UNIT I CAN USE ??? IS THERE ANY CALCULATION OR CALIBRATION .. IF YEH .. THEN PLZ JUST GIVE ME CALIBRATION STEPS FOR DPT.. THANKS YOURSSSSSSS

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HOW THE ORIFICE & PRV SIZING BE HAPPENED -- EXPLAIN IN BRIEF

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