Answer / mohamed yousuf(instrumentation

according to the formula P=F/A

Actually we are applying the 2.5 bar pressure to the
diaphram actuator. By increasing the area of diaphram we
can increse the force acting on the diaphram and that muuch
of force is more enough to actuate the stem movement.even
though 40 bar pressure is applied only to the small area
(plug of the control valve).the force actiong on it will be
very small.

Answer / waseem ahmad

Mr. Bipinchandra is right but there are more possible
answers to this. 1) what is the differential pressure across
the valve? the pressure of steam might be 40kg but the
pressure of steam across the valve might not 40kg. 2) the
use of balanced plug in control valves allow us to control
high pressure fluids with minimum actuator force.

Answer / centhile r mohan

the 2.5 bar is used to control the valve by giving it to
the diaphragm to actuate it.so the process pressure 40bar
is controlled.

Answer / bipinchandra ravalia.

The 2.5 bar used to control the valve acts on the
Diaphragm. Now the area of the diaphragm is Large and thus
the Force Per Unit Area acting on the stem is very much
greater than the Process pressure of 40bar. Thus it is not
difficult to control this process pressure with the given
2.5 bar air supply to the control valve.

Answer / sagar,kptl

By using of pneumatic control valve,that control valve have a helical spring containing tension when give pressure 2.5 bar. That pressure force acting will control the 40 bar steam

.'.P=f/a

Answer / rajender

By using Pneumatic Control Valve(Plug valve)

Answer / r_vaya

That's why in high pressures line(like super heater's  steam in power plant)  having double seated globe valves.therefor double seated plugs has line pressure both side equal (upside same and down side same ) is equal to line pressure 0 
So thus, plug will operate according valve's pressure.....

Answer / ramesh4529

yet to find

Emergency Shutdown Systems/ Plant Shutdown System.

0 Answers   CCIE,

Identification of control valve parts.

0 Answers   CCIE, Oil and Gas Jobs,

capillary type tranmitter using remote seals and capillary tubes filled with liquid of known of known density so if you wanna callibrate it just close block valve just before capilary @ high side & connect druck apply it's calibrated range pressure as normal calibration ensure low side block valve must be closed & if you asking commissioning so this is not a DP type pressure tx so simple if you wanna put in servie this tx just open high side block valve & than low side block same way i do it but still transmitter showing -13 ma.just tell me what i want to do ?

1 Answers   Gasco,

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 measure temperature from resistance of rtd?and how to measure temp from voltage of thermocouple?is there any formulas?

3 Answers  

any body please send me the old question papers of ongc test.

0 Answers   NTPC,

what is the well head protection system?

1 Answers  

Why do we need to install hook-up line differential pressure type level transmitter when the differential pressure type level transmitter with capillary are available?

2 Answers  

whats the diff b/w zero pressure and obsolute pressure

4 Answers  

Give 2 application of quartz crystal used for process parameter measurement.

1 Answers   ADMA OPCO,

Why we are using thrust bearing at turbine side?

3 Answers   Edac,

what is difference between hart signal and analog signal (4 to 20 ma)

2 Answers   Takreer,