Answer / siddhartha mishra

In open loop the varialble is for monitoring purpose e.g.
if we are using a pressure transmitter of pressure
indication only then the connection will be said to be open
loop whereas in closed lood the varialble is measured and
controlled also e.g. if we are using the pressure
transmitter as well as a control valve to maintain the
pressure in the tank then the connections will be said to
be in closed loop

Answer / pankaj singh

In open loop you will not get the feeddack from system
whereas in closed loop you will get the feedback from the
system.

Answer / senthil.doosan

example for open loop - u can only monitor the output of
the transmitter(pressure,flow,temp.level)
example for closed loop-u can monitor the output of the
transmitter (pressure,flow,temp.level) and u can control
the process by using these parameters feedback by final
control element.

Answer / jayesh

in open loop feed back is not used betwen out put and in put
and
in closed loop feed back is used betweemn out and in put .

Answer / akhil pawar

in open loop,op signal is not given to set point again,
means feedback is absent.so if op is not as we desird we
have to adjust it manually.
while in closed loop, op value is given to set point through
feedback path. when op value is given to set point , it
compare it and produce error signal which processes further
and desired value for op is adjusted autmatically.
in all modern control system, feedback is used.

Answer / ravi vaya

Open loop is not give as feed back,when close loop is give
as feed back.

An open loop`s example is any PRV,PSV etc.

And

All control valves is close loop.

Why we are using PLC instand of DCS in ESD System? can u explain any one?

2 Answers  

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Hi all, I am Mohamed from Algeria, I'm a senior Technician qualified in instrumentation. I work in an international petroleum and gas company (SONATRACH: Separation of associated gas from crude oil. Production of condensate, LPG and re-injection of dry gas) within the regulation & Control instrumentation department.I am interested for working in Qatar Petrochemical Company (QAPCO) in Qatar.Now,I am seeking a position, which is an opportunity for me to put my experience to good use and actually participate in running on this company. So, Can anyone help how to contact this company? Thanks Mohamed, mahad8331@gmail.com

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