Answer / mariyappan

Because of dead zero and live zero concept.
Dead Zero: this is basically derived from ohm's law
V=IxR. In electronics circuit minimum 250 ohm resistance is using. so V=Ix 250. Substitute I=0,1,2,3,4 after substitute 0 u will get V=0 ohm,(1;V=250 ohm,2;V=500 ohm,3;V=750 ohm,4;4=1000 ohm or 1 V) so when 4 ma is coming u will get 1 V,8 ma=2v,12 ma=3 V,16 ma=4v,etc..... u will get linearity .thats why 4 ma is choosing in all analogue value.
Live Zero: if tx is failure that time also zero value is coming.thats why 0 is not choosing

What is Erosion in a control valve?

0 Answers   CCIE, Fisher,

---

suppose there is gas flow meter I want to know weather meter calibration is done at high pressure or low pressure? pls justify.

2 Answers   Siemens,

---

A DP transmitter is used to measure the level of an open tank. The drain line of the tank is connected to a control valve, and is configured as, if the level of the tank is 90% the valve should get open 10%. And if the tank level is 10%, the valve should get open 90%. Draw wiring diagram and explain how to configure DP transmitter and control valve using HART communicator. If the span error at output is 1%, what will be the %opening of the control valve at 60% level of the tank?

0 Answers  

---

What is the purpose of the analyzer in petrochemical plant?

0 Answers   ENI, Lakshmi Machine Works,

---

How to Calibrate Transducers? Can you give me a step by ste procedure?

1 Answers  

---

Identification of ss fittings, pilot valves, relief valve.

0 Answers   CCIE,

---

What pressure results for a flow transmitter of range 0- 180t/h in the dcs and 0-301mbar in the field using square root extraction. Kindly also suggest formulae for the percentages 0,25,50,75,100?

0 Answers   Kentz,

---

(1) In turbine, what does term CDP, NI, NH, HSSOC, means. (2) What is the purpose of LO overhead tank in turbines.(3) An equipment is certified for EEX, IA, IIC,T6, what do you under stand by this.(4) what is SURGE, and how it is prevented, what is the purpose of bypass valve across AS valve.(5) Give 2 application of quartz crystal used for process parameter measurement.(6) what is meant by cold float of compressor shaft. (7) state four different types of flow measurement. For gas flow measurement mmscfd is the common unit. Expand the unit and specify significance of word S in the unit.(8) what is meant by Gap voltage, in vibration measurement. Normally how much Gap voltage is set and state the reason.(9) what will the new flow factor if D/P transmitter is Re-Ranged from 25” wc to 50” wc.(10) what is the usage of QDV & Volume booster.

0 Answers   ADMA OPCO,

---

State some of balance principle’ advantages?

0 Answers  

---

Reasons for using current as signal

1 Answers  

---

the whole paper was based on Transducers..questions like define repeatability, error,accuracy,precision..den there were many q. on the conversion of Pa to mmHg and other units.. also..der wer few Q. on some level sensors(with diagram)

0 Answers   GNFC,

---

use of split range ? where it is used ? in which control loop it is used ?

0 Answers  

---