industrial instrumentation 2010

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6432 [ Turn over

Name : ……………………………………………………………

Roll No. : ………………………………………………………..

Invigilator’s Signature : ………………………………………..

CS/B.Tech (ICE)/SEM-6/IC-603/2010

2010

INDUSTRIAL INSTRUMENTATION – II Time Allotted : 3 Hours Full Marks : 70

The figures in the margin indicate full marks.

Candidates are required to give their answers in their own words

as far as practicable.

GROUP – A

( Multiple Choice Type Questions )

1. Choose the correct alternatives for any ten of the following :

10 × 1 = 10

i) The pressure drop across an orifice is measured for a particular flow rate. If the flow rate is doubled, keeping all other parameters constant, what would happen to the pressure drop ?

a) It will remain the same

b) It will also be doubled

c) It will be halved

d) It will increase four items.

ii) Which of the following flowmeters has the lowest pressure drop for a given range of flow ?

a) Orifice meter b) Venturimeter

c) Flow Nozzle d) Rotameter.



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iii) A flow transmitter with a 4–20 mA output has a

calibration range of 1·0 – 6·0

!

m3

/sec. What flow rate is

indicated by a current of 12 mA ?

a) 7·0

!

m3

/sec b) 3·5

!

m3

/sec

c) 4·5

!

m3

/sec d) 3·6

!

m3

/sec.

iv) In case of capacitance level measurement, capacitance

will ................. with the increase of level

a) increase

b) decrease

c) remain same

d) no relation between level and capacitance.

v) The basic principle of float type of level sensor is

a) force balance b) motion balance

c) energy balance d) none of these.

vi) The Zener barrier is used in

a) flame proof instrument

b) intrinsically safe instrument

c) both (a) and (b)

d) none of these.



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vii) A Reynolds number of 1000 indicates

a) Turbulent flow

b) Laminar flow

c) A flow which can either be turbulent or laminar

d) Transition flow.

viii) Square root extractor is not required for

a) Venturimeter

b) Electromagnetic flowmeter

c) Rotameter

d) Pitot tube.

ix) Reynolds number

a) increases with increase in average velocity of liquid

b) decreases with increase in absolute viscosity of

liquid

c) increases with increase in density of flowing liquid

d) all of these.

x) Determine the height of liquid column in a closed tank.

The hydrostatic pressure is given as 3000

!

kg / m2 and

the external pressure on liquid in the tank is

450

!

kg / m2. Assume density of water is 1000

!

kg / m3.

a) 2·55 m b) 2·65 m

c) 2·85 m d) 2·99 m.



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xi) Electrostatic discharge takes place at

a) very high voltage and very low current

b) very low voltage and very low current

c) very high voltage and very high current

d) very low voltage and very high current.

xii) IP and NEMA are used for

a) specifying the regulated power supply

b) defining the protection level of the devices

c) designing integrated circuits

d) defining the protection level of enclosures.

GROUP – B ( Short Answer Type Questions )

Answer any three of the following. 3 × 5 = 15

2. a) Define the terms ‘turn-down’ and ‘rangeability’ in case

of a flowmeter ?

b) What is mass flow rate ?

c) Explain the terms ‘discharge coefficients’ and ‘β-ratio’ in

case of a flowmeter. 2 + 1 + 2

3. a) What is ‘Von Karman vortex street’ ? How is it related to

fluid flow measurement ?

b) What are the different vortex detection systems ?

1 + 3 + 1



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4. a) What is the principle of turbine flowmeter ?

b) How do the density and viscosity variation of fluid affect

the measurement through turbine flowmeter ? 3 + 2

5. Derive the expression for the ideal volume flow rate in

variable head type flowmeter. 5

6. a) What is the basic classification of hazardous areas ?

b) What is an enclosure ?

c) What do you mean by intrinsic safety ? 3 + 1 + 1

GROUP – C ( Long Answer Type Questions )

Answer any three of the following. 3 × 15 = 45

7. a) With the help of a neat sketch, explain how a torque-

displacer assembly is used for the measurement of

liquid level in a tank.

b) Can the capacitive method of level gauging be used in

conducting type liquids as well ? If yes describe the

principle of operation. Show, how this is done for

conducting type liquids ?

c) How probe can be designed for capacitive type level

measurement purpose ? 6 + 3 + 4 + 2



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8. a) Explain the working of a transit time ultrasonic flow-

meter. What technique is adopted to minimize

dependence of measurement on the sonic velocity in the

medium ?

b) Describe with a neat sketch, the construction and

working principle of a radiation level indicator. 7 + 3 + 5

9. a) What is Coriolis acceleration ? How is it used in mass

flow rate measurement ? Discuss its merits and

demerits.

b) Describe with neat sketch, the construction and

working of thermal mass flowmeter. ( 2 + 5 + 2 ) + 6

10. a) Draw and explain a scheme for level measurement of

non-conducting type liquid with bare capacitance probe

in a conducting vessel.

b) Draw the equivalent circuit of the scheme. Find out the

equivalent capacitance of that circuit and show that

equivalent capacitance will vary linearly with the level of

the tank.

c) What modification should be done if the liquid is

conducting ? ( 4 + 3 ) + ( 3 + 3 ) + 2



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11. Write short notes on any three of the following : 3 × 5

a) Ultrasonic level sensor

b) Thermal mass flow measurement

c) Microwave level switches

d) Electromagnetic flowmeter

e) Shielding.

industrial instrumentation 2010

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