Process Control and Instrumentation Flashcards
Which of the following is an undesirable dynamic characteristic of an instrument?
Time lag
Which of the following is not the triple point of water?
32 °R
Load cells are used for the measurement of ___?
Weight
Which of the following is the dynamic characteristics of an instrument?
Fidelity
Pick out the wrong statement.
CO2 is the strongest paramagnetic gas.
The __________ of a vapor pressure thermometer is a functioning element.
Pointer
.
A negative gain margin expressed in decibels means a/an __________ system.
Unstable
Thermistor, which has high temperature co-efficient of resistivity, is used as the sensing element in resistance thermometer. It is a/an
Solid semi-conductor
Flapper nozzle is used in a/an __________ controller.
Pneumatic
Typical specifications for design stipulates the gain margin and phase margin to be respectively
> 1.7 and >30°
Working principle of radiation pyrometer is based on the _______.
Stefan-Boltzmann Law
Which of the following relates the emf generated in a single homogeneous wire to the temperature difference?
Thomson Effect
Dilute wine was used as a thermometric liquid initially to develop temperature scale. First emperical temperature scale developed was the __________ scale.
Fahrenheit
In a single tank system, the transfer function of level to inlet flow rate is
R/(TS + 1)
Which of the following is a desirable characteristic of an instrument?
High Fidelity
The operation of a rotameter is based on
Variable flow area
The temperature of tempering oil baths maintained at 400°C during heat treatment of steel is measured by a/an __________ thermocouple.
iron-constantan
Which of the following temperature measuring instruments need not touch the object whose temperature is being measured?
Radiation/Infrared Pyrometer
Thermal conductivity measurement comprises the working principle of a
CO2 analyzer
The closed loop pole of a stable second order system could be
both real and negative
Transfer function of transportation lag is
e^(-TS)
The maximum service temperature for fibre glass used as thermocouple wire insulation material is __________ °C.
500
Which of the following controllers has the least maximum deviation?
P-D controller
Zirconia probe is used for the continuous measurment of __________ flue gases going out of the furnace.
oxygen in
The transfer function for a PID controller is (where, τi is the integral (reset) time and τD is the derivative time.)
Kc (1 + 1/τiS + τDS)
Nichol’s chart deals with
closed loop values vs. open loop values
Which of the following thermocouples will give the highest output for the same value of hot and cold junction temperature?
Chromel-constantan
A proportional controller with a gain of Kc is used to control a first order process. The offset will increase, if
Kc is reduced
For an input forcing function, X(t) = 2t^2, the Laplace transform of this function is
4/s^3
The __________ of a vapor pressure thermometer is a secondary element.
Bourdon Tube
Emf developed by a thermocouple, while measuring a temperature of 600°C is about 5.5 mV. The type of thermocouple used is
platinum-platinum+rhodium
Which of the following relates the absorption & evolution of heat at the junctions of a thermocouple to the current flow in the circuit?
Peltier Effect
