Instrumentation Flashcards
Strongest paramagnetic gas
O2
Negative gain margin in decibels means ____ system
unstable
Thermistor is a/an
solid semi-conductor
Flapper nozzle is used in
pneumatic controller
Working principle of radiation pyrometer
Stefan Boltzman
Undesirable characteristic of instrument
Time Lag
Functioning element of VP thermometer
Pointer
Relates emf in a single homogeneous wire to temp difference
Thomson Effect
Temperature of tempering oil baths maintained at 400C during heat treatment of steel
Iron Constantan
Thermal conductivity measurement
CO2 analyzer
Closed loop pole of a stable second order system would be
real and negative
Smoke density of flue gas out of the chimney
Photoelectric cells
Maximum service temperature for fiber kept in Boiling water
500 C
Zirconia probe is used in the measurement of
O2 in the flue gas
Compositional analysis of ___ is done using mass spectrometer
Isotope
Highest output for the same value of hot, cold junction temperature
Chromel-Constantan
Secondary element of VP thermometer
Bourdon Tube
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
The second order system with the transfer functionhas a damping ratio of
0.5
In a shell and tube heat exchanger, the flow rate of heating/cooling fluid is the __________ variable.
manipulated
Which of the following thermocouples can measure the maximum temperature ?
Tungsten-molybdenum
temperature scale assigns 0° to the ‘ice point’ and 80° to the ‘steam point’
Reumur
Degree to which an instrument indicates the changes in measured variable without dynamic error is called its
Fidelity
Thermistors are made of
metal oxides
Thermocouple in a thermal well behaves as a true
Multiple first order system
The transfer function for a P-D controller is
Kc(1+τDs)
Bode diagram is a plot of
log (AR)vs. log (f) and (Φ) vs. log (f)q
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
True or False. CSTR can be considered as a distributed parameter system.
False
The time constant of a first order process with resistance R and capacitance C is
RC
sinusoidal variation in the input passing through a linear first order system
gets attentuated (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
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 is1
180 C
Measurement of pressure in ammonia reactor is done by
Bourdon tube
The fluid used in hydraulic controller is
oil
“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
Which thermocouple can be used to measure a temperature of around 1400°C
Platinum Platinum/Rhodium
Which of the following filled system expansion thermometer has the capability to measure the lowest temperature ?
Alcohol in glass thermometer
Which of the following can not measure a temperature of 1600°C ?
Platinum resistance thermometer
The temperature range for which copper resistance thermometer can be used is __________ °C
-200 to 150
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 gauge
Alphatron measures pressure __________ microns.
> 3
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
The term analogous to the electrical current in a thermal system is the
heat flow rate
Reset rate
Integral time
What is the ratio of output amplitude to input amplitude for a sinusoidal forcing function in a first order system ?
less than 1
Which of the following is a ‘contact’ pyrometer
resistance pyrometer
Use ofI-control along withP-control facilitates
elimination of offset
Liquid discharge from a tank or reservoir can not be measured by
orifice meters
are analysed using a polarograph
solids
On-off controllers are normally used for
low loads
Magnetic flowmeters are generally not used for the velocity/flow measurement of hydrocarbons due to their
low electrical conductivity
Which of the following controllers has maximum offset ?
P controller
Pressure of 0.01 psi (absolute) can be measured by __________ gauge.
Mcloid
Which of the following does not figure in the list of seven substances selected for international temperature scale ?
Zinc and Mercury
pH meter has
2
cannot be used to test the stability of a control system containing transportation lag.
Routh test
When a bare thermocouple is covered by a protective sheath, the response becomes
slower, non oscillatory
What is the normal percentage of rhodium in platinum + rhodium element used in the thermocouple ?
13
Helium gas constant volume thermometer is suitable for the measurement of a temperature of __________ °C.
<0
Which of the following thermocouples is the most suitable for measuring a temperature of about 1600°C in an oxidizing atmosphere ?
P-P-R
Mercury thermometer can be used to measure the temperature upto __________ °C.
350
Which of the following is not a differential pressure flow meter ?
Rotameter
A typical example of a physical system with under damped characteristic is a
spring loaded diaphragm valve.
aneroid barometer measures the __________ pressure.
absolute
The offset introduced by proportional controller with gainKcin response of first order system can be reduced by
integral control
To increase the speed of response of a pressure spring liquid or gas expansion thermometer, the clearance space between the thermometer bulb and the thermal well should not be filled with
air
Emf generated in a thermocouple depends on the temperature
difference between hot and cold junctions
Radiation thermometer can not measure the temperature
liquid oxygen
Temperature measurement by optical pyrometer is done above __________ point, which is 1063°C.
gold
stability method uses open loop transfer function
Nyquist
A pyranometer is an instrument used for measuring the
global radiation
Composition of alloys can be determined by
polarograph
