Process Control and Instrumentation

Question 1

Which of the following is an undesirable dynamic characteristic of an instrument?

Answer 1

Time lag

Question 2

Which of the following is not the triple point of water?

Answer 2

32 °R

Question 3

Load cells are used for the measurement of ___?

Answer 3

Weight

Question 4

Which of the following is the dynamic characteristics of an instrument?

Answer 4

Fidelity

Question 5

Pick out the wrong statement.

Answer 5

CO2 is the strongest paramagnetic gas.

Question 6

The __________ of a vapor pressure thermometer is a functioning element.

Answer 6

Pointer

Question 7

.

A negative gain margin expressed in decibels means a/an __________ system.

Answer 7

Unstable

Question 8

Thermistor, which has high temperature co-efficient of resistivity, is used as the sensing element in resistance thermometer. It is a/an

Answer 8

Solid semi-conductor

Question 9

Flapper nozzle is used in a/an __________ controller.

Answer 9

Pneumatic

Question 10

Typical specifications for design stipulates the gain margin and phase margin to be respectively

Answer 10

> 1.7 and >30°

Question 11

Working principle of radiation pyrometer is based on the _______.

Answer 11

Stefan-Boltzmann Law

Question 12

Which of the following relates the emf generated in a single homogeneous wire to the temperature difference?

Answer 12

Thomson Effect

Question 13

Dilute wine was used as a thermometric liquid initially to develop temperature scale. First emperical temperature scale developed was the __________ scale.

Answer 13

Fahrenheit

Question 14

In a single tank system, the transfer function of level to inlet flow rate is

Answer 14

R/(TS + 1)

Question 15

Which of the following is a desirable characteristic of an instrument?

Answer 15

High Fidelity

Question 16

The operation of a rotameter is based on

Answer 16

Variable flow area

Question 17

The temperature of tempering oil baths maintained at 400°C during heat treatment of steel is measured by a/an __________ thermocouple.

Answer 17

iron-constantan

Question 18

Which of the following temperature measuring instruments need not touch the object whose temperature is being measured?

Answer 18

Radiation/Infrared Pyrometer

Question 19

Thermal conductivity measurement comprises the working principle of a

Answer 19

CO2 analyzer

Question 20

The closed loop pole of a stable second order system could be

Answer 20

both real and negative

Question 21

Transfer function of transportation lag is

Answer 21

e^(-TS)

Question 22

The maximum service temperature for fibre glass used as thermocouple wire insulation material is __________ °C.

Answer 22

500

Question 23

Which of the following controllers has the least maximum deviation?

Answer 23

P-D controller

Question 24

Zirconia probe is used for the continuous measurment of __________ flue gases going out of the furnace.

Answer 24

oxygen in

Question 25

The transfer function for a PID controller is (where, τi is the integral (reset) time and τD is the derivative time.)

Answer 25

Kc (1 + 1/τiS + τDS)

Question 26

Nichol’s chart deals with

Answer 26

closed loop values vs. open loop values

Question 27

Which of the following thermocouples will give the highest output for the same value of hot and cold junction temperature?

Answer 27

Chromel-constantan

Question 28

A proportional controller with a gain of Kc is used to control a first order process. The offset will increase, if

Answer 28

Kc is reduced

Question 29

For an input forcing function, X(t) = 2t^2, the Laplace transform of this function is

Answer 29

4/s^3

Question 30

The __________ of a vapor pressure thermometer is a secondary element.

Answer 30

Bourdon Tube

Question 31

Emf developed by a thermocouple, while measuring a temperature of 600°C is about 5.5 mV. The type of thermocouple used is

Answer 31

platinum-platinum+rhodium

Question 32

Which of the following relates the absorption & evolution of heat at the junctions of a thermocouple to the current flow in the circuit?

Answer 32

Peltier Effect