Answer / goutam chatterjee

first of all we cant say any valve as a control valve with
out positioner... because we know that control valve is a
final control element.. we only say any valve as a control
valve when its acted as percentage operation as per process
requirement. with out positioner this is acted as a simple
on off valve... because percentage opening not possible with
out positioner... & we need to calibration the positioner
because cv alwys maintain the process in aspect of its final
contron ability.... i.e if process need to open the cv 25%
if the positioner not calibrated then it may be open 30 or
10 % for example... thats why we need to calibrate the
positioner.....

Answer / ghanshyam khatri

yes u can use without positioner,potioner is used for quiq
operation not for control cv is control through 0.2 to 1.0
kg/cm2 u can give it directly but u need to adjust bench
set spring pressure is .2 to 1kg.

Answer / senthil r.m

my dear,
when there is no positioner it is not called as control valve.i think u dont know about it.we will give 4 to 20 milliamps to the positioner accordin to tht the valve throttles b/w 0 to 100%.Tuning is different concept which i can give u details to go through it.senthilrmohan@gmail.com

Answer / inst engg

YES, BUT IT IS NOT PERMANENT REMOVE THE MAIL LINE (FORM THE
POSITIONER)TO THE CV AND GIVE THE SUPPLY PRESSURE.
TUNNING IS REQUIRED FOR EXACT PERFORMANCE(Eg. YOUR CV HAVING
2% ERROR ,YOUR CONTROLLER IS GIVING 23% CLOSE BUT YOUR CV
WILL CLOSE 25% IT WILL AFFECT THE PROCESS) AND PERFECT
SEATING OF GATE.

What is the difference between Analytical instruments and other instruments?

7 Answers   Schenck,

---

WHAT IS ANNUBAR?

7 Answers  

---

working principle of lvdt?

2 Answers  

---

What is Fieldbus?

3 Answers   NSL,

---

where cn i find the previous years question paper for psu exam???????//

0 Answers  

---

1.what is the effect of vapour presuure in orifice plate flow measurement 2.which is more effective 2 pressure sensors or one single differential pressure sensor in orifice plate measurement 3.how to design a v/i converter and i/v converter 4.how many type of thermocouple are there 5.how many leads are there in thermocouple measurement 6.how pressure sensors are connected in level measurement in differential pressure method 7.what is the output of capacitive pressure sensor (ac or dc),how its o/p is signal charactarized 8.what is the physical meaning of discharge coeeficient,why it is calculated,orifice plate what is its value,why it is less than 1,Q at upstream is equal to or not equal to Q at downstream of orifice plate why?what is vena contracta in orifice plate 9.why rotameter is called variable area flowmeter,it can measure flow even if area is not varying,why it is made tapered 10.design a 10 bit counter ,which counter you will prefer 11.how to remove self heating error in RTD 12.which is more sensitive pt100 or pt50 13.why thermocouple are connected in parallel 14.what is lead contact error in RTD,how to avoid 15.what is P,PI,PID,PD controller,why there is no ID controller 16.what is override,split range,sequential,ratio,feedforward,cascade controller 17.why we moved from SR to JK and then JK to master slave JK flipflop,give correct reason 18.how to measure level of a closed container which contains vapour and liquid,remember no vapour gas should be leaked,so ultrasonic and capacitive is not an option,design another method 19.how to design horse race counter including sensors and signal conditioning element 20.what is bevelling

0 Answers   BARC,

---

How can we measure the level of a closed system like drum

3 Answers  

---

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

1 Answers   Bapco Bahrain Petroleum Company,

---

why level transmitter input is given 4to20ma

2 Answers   Sabic,

---

how to calibrate steam control valve in steam turbine

0 Answers  

---

I have a LT of 10000mmwc range. can i use this LT in 1000mmwc range of tank?? if yes than what happened???

3 Answers   Nirma,

---

how to calibrate the interface leveltrol

1 Answers   Lanco,

---