IPC Flashcards
Which of the following is an undesirable dynamic characteristic of an instrument ?
Time lag
Load cells are used for the measurement of
Weight
Which of the following is the dynamic characteristics of an instrument ?
Fidelity
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
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
Stafan-Boltzman law
Dilute wine was used as a thermometric liquid initially to develop temperature scale. First emperical temperature scale developed was the __________ scale.
Fahrenheit
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 com-prises the working principle of a
CO2analyser
Response of a system to a sinusoidal input is called __________ response.
Frequency
The closed loop pole of a stable second order system could be
both real and negative.
Smoke density of the flue gas going out of the chimney is measured by a
photo electric cell
The maximum service temperature for fibre glass used as thermocouple wire insulation material is __________ °C.
500
Zirconia probe is used for the continuous measurment of __________ flue gases going out of the furnace.
Oxygen in
Compositional analysis of __________ is done using mass spectrometer.
an isotope
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.
is undesirable in thermocouples used in industries,
Non-linear relation of emf to temperature
Continuous shell temperature measurement in a liquid-liquid heat exchanger is done by a
thermocouple
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
In a shell and tube heat exchanger, the flow rate of heating/cooling fluid is the __________ variable.
manipulated
A non-linear chemical system is exemplified by a/an
non-isothermal CSTR
Radiation pyrometers as compared to thermocouples
can measure higher temperature.
Liquid flow rate in a small channel is best measured by a/an
pitot tube
Specific gravity of a liquid can not be measured by a/an
anemometer
temperature scale assigns 0° to the ‘ice point’ and 80° to the ‘steam point’.
Reumur
Dead zone is the
maximum change in the variable that does not change the reading of the instrument.
Humidity of air can be determined by a
sling psychrometer
Working principle of disappearing filament type optical pyrometer is based on the
Wien’s law
Strain gage uses an electrical conductor wire, which when elastically stretched increases in length and reduces in diameter. Both these dimensional changes result in __________ in the electrical resistance of the wire.
increase
Range of hydrogen gas constant volume themometer is __________ °C.
0 to 100
The __________ of a vapor pressure thermometer is a primary element.
Bulb
A sinusoidal variation in the input passing through a linear first order system
gets attenuated (magnitude decreases).
Nitrogen gas constant volume thermometer is suitable for measuring a temperature of __________ °C.
> 100
Pick out the most suitable instrument for measuring temperature in the range of-40 to 425°C.
bimetallic thermometer
Accurate temperature measurement performance of a radiation pyrometer can not be affected, if the
object and surrounding are at almost the same temperature.
Relationship between absorption/evolution of heat at the thermocouple junctions and the current flow in the circuit is given by __________ effect.
Peltier
Configuration of Bourdon spring tube is never made of __________ shape.
circular
According to Bode stability criterian, a system is unstable, if the open loop frequency response exhibits an amplitude ratio exceeding unity at frequency for which phase lag is
180°
In a closed loop system, the process to be controlled is an integrating process with transfer function l/2s. The controller proposed to be used in an integral controller with transfer function 1/T1s. When a step change in set point is applied to such a closed loop system, the controlled variable will exhibit
underdamped response
Measurement of pressure in ammonia reactor is done by
Bourdon gauge
Flow rate of a river is measured by a/an
vane meter
Flow rate of those fluids which are insensitive to changes in their density, viscosity or flow velocity profile can be best measured by a
magnetic flowmeter
A control system is unstable, if the open loop frequency response exhibits an amplitude ratio exceeding unity at the crossover frequency.” This is __________ criterion.
Bode stability
Feed forward controller accounts for the __________ changes.
load
Paramagnetism method is not used for the composition determination of __________ in gases.
carbon dioxide
An amplitude ratio of 0.1 corresponds to __________ decibels.
-20
Pressure of 0.0001 absolute psi can be measured by __________ gauge.
Mcloid
thermometer can not measure sub-zero (< 0° C) temperature
Bimetallic
Starting temperature of optical radiation pyrometer is __________ °C.
800
Liquid argon level in a pressurised storage tank (at 3 kg/cm2 ) is measured by a/an
differential pressure gage
The deflection of the free end of the bimetallic strips in a bimetallic thermometer with temperature is nearly
linear
What is the ratio of output amplitude to input amplitude for a sinusoidal forcing function in a first order system ?
< 1
Reset rate is the another term used for __________ time.
integral
Continuous measurement of moisture in paper is done by
high resistance Wheatstone’s bridge circuit.
The amplitude ratio for the sinusoidal response of a __________ is 1.
transportation lag
The response of two tanks of same size and resistance in series is
critically damped
Measurement of sub-zero Celcius temperature in industry is done most commonly by
resistance thermometers
Liquid discharge from a tank or reservoir can not be measured by
orificemeters
Magnetic flowmeters are generally not used for the velocity/flow measurement of hydrocarbons due to their
low electrical conductivity
The time constant of a unity gain, first order plus time delay process is 5 min. If the phase lag at a frequency of 0.2 rad/min is 60°, then the dead time (in minutes) is
5π/12
A constant volume gas thermometer employing __________ is used to measure sub-zero (i.e., < 0° C) temperature.
helium
When a bare thermocouple is covered by a protective sheath, the response becomes
slower and non-oscillatory.
What is the normal percentage of rhodium in platinum + rhodium element used in the thermocouple ?
13