process control section 2 Flashcards by irish guillermo

The transfer function for an ideal proportional
plus reset controller (reset time T) is
a. Kc(1 + 1/TS)
b. Kc(1+TS)
c. Kc/(1+TS)
d. Kc(1+T/S)

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A non-linear chemical system is exemplified by
a/an
a. isothermal CSTR
b. Mixer
c. non-isothermal CSTR
d. none of these

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The frequency response of a first order system,
has a phase shift with lower and upper bounds given
by
a. ∞, π/2
b. -π/2, π/2
c. -π/2, 0
d. 0, π/2

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Gas chromatography is used for the measurement
of
a. Temperature
b. Pressure
c. Concentration
d. flow rate

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Which of the following thermocouples can
measure the maximum temperature?
a. Platinum-rhodium
b. Tungsten-molybdenum
c. Chromel-alumel
d. Iron-constantan

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Radiation pyrometers as compared to
thermocouples
a. has a slower speed of response.
b. can measure higher temperature.
c. can’t measure the temperature of moving
objects.
d. is more affected by corrosive atmosphere.

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Liquid flow rate in a small channel is best
measured by a/an
a. Weir
b. pitot tube
c. vane meter
d. venturimeter

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Specific gravity of a liquid can not be measured
by a/an
a. Anemometer
b. specific gravity bottle
c. Pycnometer
d. hydrometer

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__________ temperature scale assigns 0° to the
‘ice point’ and 80° to the ‘steam point’.
a. Celcius
b. Rankine
c. Reumur
d. Farenhite

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Dead zone is the
a. same as time constant.
b. same as transportation lag.
c. maximum change in the variable that does
not change the reading of the instrument.
d. none of these.

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Which of the following thermometers is not
suitable for distant reading up to 60 metres?
a. Vapor pressure thermometer
b. Mercury in glass thermometer
c. Constant volume gas thermometer
d. Resistance thermometer

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Degree to which an instrument indicates the
changes in measured variable without dynamic
error is called its
a. speed of response
b. Reproducibility
c. Fidelity
d. static characteristics

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Thermistors are made of
a. ultra pure metals
b. metal oxides
c. iron-copper alloys
d. nickel-chromium alloys

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A barometer measures the __________
pressure.
a. Absolute
b. Gauge
c. absolute as well as gauge
d. dynamic

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Humidity of air can be determined by a
a. Chromatograph
b. sling psychrometer
c. mass spectrometer
d. polarimeter

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Thermocouple in a thermal well behaves as a
true
a. first order system.
b. second order system (overdamped).
c. multiple first order system.
d. second order system (underdamped).

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The transfer function for a P-D controller is
a. Kc(1+τD s)
b. Kc(1 +1/τD s)
c. Kc τD s
d. Kc/τD s

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Bode diagram is a plot of
a. log (AR) vs. log (f) and (Φ) vs. log (f).
b. log (AR) vs. f and log Φ vs.f.
c. AR vs. log (f) and Φ vs. log (f).
d. none of these.

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Working principle of disappearing filament type
optical pyrometer is based on the
a. Wien’s law
b. Seebeck effect
c. Kirchoff’s law
d. Peltier effect

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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.
a. no change
b. Decrease
c. Increase
d. exponential decrease

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Pick out the wrong statement
a. Proportional controller is normally used for
level control in industrial applications.
b. CSTR can be considered as a distributed
parameter system.
c. Distributed parameter approach gives
partial differential equation.
d. Non-linear behaviour is exemplified by an
on-off controller.

Range of hydrogen gas constant volume
themometer is __________ °C.
a. -10 to 20
b. 0 to 100
c. 100 - 500
d. 400 - 1000

The initial value (t=0) of the unit step response
of the transfer function [(s + 1)/(2s + 1)] is
a. 0
b. 1⁄2
c. 1
d. 2

The __________ of a vapor pressure
thermometer is a primary element.
a. Pointer
b. Bourdon tube
c. Bulb
d. none of these

The time constant of a first order process with resistance R and capacitance C is a. R + C b. R - C c. RC d. 1/RC

A sinusoidal variation in the input passing through a linear first order system a. becomes more oscillatory (frequency increases). b. becomes less oscillatory (frequency decreases). c. gets amplified (magnitude increases). d. gets attenuated (magnitude decreases).

Nitrogen gas constant volume thermometer is suitable for measuring a temperature of __________ °C. a. 0-100 b. < 0 c. > 100. d. > 50

What is the overall transfer function (C/R) of the following block diagram if G = G1. G2. G3 and H = H1.H2. a. 1/(1+GH) b. G/(1+GH) c. H/(1+GH) d. G/(1-GH)

Pick out the most suitable instrument for measuring temperature in the range of-40 to 425°C. a. mercury thermometer b. bimetallic thermometer c. radiation pyrometer d. none of these

Accurate temperature measurement performance of a radiation pyrometer can not be affected, if the a. enhancement or attentuation of redia-tion occurs in the sighting path. b. object and surrounding are at almost the same temperature. c. object has varying emissivity. d. object is transparent.

Relationship between absorption/evolution of heat at the thermocouple junctions and the current flow in the circuit is given by __________ effect. a. Peltier b. Thomson c. Seebeck d. none of these

Configuration of Bourdon spring tube is never made of __________ shape. a. circular b. semi-circular c. helical d. spiral

Thermodynamic celcius scale of temperature measurement is a. defined on the basis of melting point of ice and evaporation temperature of water vapor. b. defined on the basis of melting point of ice and condensation temperature of water vapor. c. having an interval of 100° between ice point to steam point. d. both (b) and (c)

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 a. 0° b. 45° c. 90° d. 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 a. overdamped response. b. underdamped response. c. undamped response. d. unstable response.

Resistance of a gas in a vessel is given by (where, P = pressure, V = volume of the vessel, n = no. of moles of the gas, R = gas constant) a. V/nRT b. nRT/V c. nRT/P d. P/nRT

Measurement of pressure in ammonia reactor is done by a. Bourdon gauge b. U-tube manometer c. Inclined tube manometer d. Pirani guage

The fluid used in hydraulic controller is a. Water b. Steam c. Air d. oil

Flow rate of a river is measured by a/an a. pitot tube b. vane meter c. kennison nozzle d. open weir

Which of the following thermocouple materials does not contain nickel? a. Alumel b. Chromel c. Constantan d. None of these.

Flow rate of those fluids which are insensitive to changes in their density, viscosity or flow velocity profile can be best measured by a a. magnetic flowmeter b. pitot tube c. flow nozzle type flowmeter d. turbine flowmeter

Identify an unbounded input from inputs whose transfer functions are given below a. 1 b. 1/S c. 1/S^2 d. 1/(S^2 + 1)

"A control system is unstable, if the open loop frequency response exhibits an amplitude ratio exceeding unity at the crossover frequency." This is __________ criterion. a. Bode stability b. Nyquist c. Routh stability d. none of these

Feed forward controller accounts for the __________ changes. a. set point b. Load c. both (a) & (b) d. neither (a) nor (b)

Which thermocouple can be used to measure a temperature of around 1400°C? a. Copper-constantan b. Aluminium-chromel c. Platinum-platinum+rhodium d. None of these

Which of the following filled system expansion thermometer has the capability to measure the lowest temperature? a. Mercury in glass thermometer b. Mercury in steel thermometer c. Alcohol in glass thermometer d. Fused metal (Na or K) in steel thermometer

Concentration of sugar solution can be determined by the a. Polarimetry b. flame photometry c. emission spectroscopy d. oscillometry

In a single tank system, the transfer function of __________ to inlet flow rate is 1/TS+1. a. outlet flow rate b. Level c. both (a) & (b) d. neither (a) nor (b)

Which of the following can not measure a temperature of 1600°C? a. Platinum resistance thermometer b. Thermocouple c. Photo-electric pyrometer d. Radiation pyrometer