ENGINEERING KNOWLEDGE - GENERAL
MARINE CONTROL SYSTEMS AND INSTRUMENTATION 2970 The controller set point of an automatic control system is 65°C. The
valve closes when the output temperature reaches 70°C, and reopens when the temperature falls below 60°C. The type of positioning action in this controller is known as ________.
2971 In a pneumatic automation system, a unit producing a signal to govern the position of the controller of the measured variable, relative to the value of the measured variable, is said to have _______________.
A. one-position single-point A. reset action
B. two-position single-point B. proportional action
C. one-position differential-gap C. two position action
D. two-position differential-gap D. rate action
Ans: D Ans: B
2972 If the loading air pressure for a diaphragm controlled valve drops below the designed operating pressure, the valve will
________________.
2973 Every automated machinery plant must have an "engineer's assistance" alarm. Power for this alarm should be taken from the _________________.
A. fail to stroke open A. main bus
B. stroke slowly through its operating range B. emergency bus
C. stroke rapidly closed C. standby generator
D. fail to stroke through its complete range D. general alarm power supply
Ans: D Ans: D
2974 The effect of "reset", when added to a proportional controller is to _______________.
2975 Which of the following statements expresses the function of proportional-plus-reset action?
A. make the controller correction proportional to the rate at which the input change takes place
A. The action measures the rate of time of the final control element.
B. accelerate the corrective action so as to minimize the possibility of hunting
B. The action gives control without offset under all load conditions.
C. make the corrective action of the controller proportional to the deviation of the controlled variable from the set point
C. The action combines proportional-position action and rate action.
D. repeat the proportional action until the controlled variable returns to the set point
D. The action is very unstable for anything but constant load conditions.
Ans: D Ans: B
2976 One disadvantage of proportional-position action is that __________.
2977 Filters are installed ahead of air line lubricators for the primary purpose of removing ___________.
A. corrective action is only proportional to offset A. the heat of compression B. exact correction can be made only when there is no change in load B. air supply pressure pulses
C. the controlled variable is stabilized C. moisture in the air supply
D. the corrective action is only proportional to the deviation D. turbulence in the air supply
Ans: D Ans: C
2978 The cylinder unloading mechanism used on low pressure air compressors is an example of which mode of control?
2979 Which of the listed devices would be installed at a control system air pressure reducing station?
A. Two position A. Moisture separator
B. Derivative B. Vacuum breaker
C. Integral C. Lubricator
D. Single speed floating D. Nonreturn valve
Ans: A Ans: A
2980 Reset control is also referred to as ____________. 2981 Reset control is also referred to as ____________.
A. proportional speed floating control A. derivative control
B. derivative control B. integral control
C. rate control C. rate control
D. proportional control D. proportional control
Ans: A Ans: B
2982 The quantity or condition which is measured and controlled is known as the ____________.
2983 A computing relay is used in a pneumatic control system to _______________.
A. controlled variable A. extract square roots
B. manipulated variable B. square
C. set point C. divide
D. control point D. all of the above
Ans: A Ans: D
2984 The reset process control mode is also considered to be the same as _________. I. proportional speed floating control II. derivative control
2985 A mode of control, whereby the speed of motion of the final control element is linearly proportional to the deviation of the controlled variable from set point, is called _________.
A. I only A. rate control
B. II only B. derivative control
C. Both I and II C. two position control
D. Neither I nor II D. integral control
Ans: A Ans: D
2986 Which of the following definitions can be used to define the term
"offset" as a characteristic of controller action?
2987 Which of the following definitions best describes sensitivity as a characteristic of controller action?
A. The period of time in which the set point and the control point coincide.
A. The ratio of the output in response to a specified change to the input which caused it.
B. The periodic change between the set point and the control point. B. The steady state difference between the control point and the value of the controlled variable corresponding to the set point.
C. The variable difference between the set point and the control point. C. The variation of the manipulated variable produced by the mode of control.
D. The constant difference between the set point and the control point.
D. The time difference between the input change and the output change of the controller.
Ans: D Ans: A
2988 Why is it necessary to spin the piston of a dead weight gage tester while carrying out the calibrations of pressure gages?
2989 A mandatory characteristic of a pure amplifier is that _______________.
A. Prevent formation of a vacuum. A. the form of the input and output energies must be the same B. Eliminate the formation of air bubbles. B. the ratio of the output to the input must always be greater than the
numerical value of "one"
C. Prevent the piston rod from sticking. C. the form of the input and output energies must be different D. To assist in calibrating the dead weight tester. D. the action must be either integral or derivative
Ans: C Ans: A
2990 The control mode in which the final control element is moved from one of two fixed positions to the other is known as
_______________.
2991 A control action which produces a corrective signal relative to the speed at which the controlled variable is changing is known as _____________.
A. dead band action A. reset action
B. neutral zone action B. integral action
C. range C. derivative action
D. on-off action D. proportional action
Ans: D Ans: C
2992 A hydrometer measures specific gravity by comparing the ______________.
2993 In an automated control system, which of the following statements would apply to any type of closed loop system?
A. density of a substance in water with the density of the same subject in air
A. The manipulated variables are adjusted only from the input demand signals without monitoring the outlet conditions or variables.
B. differences in weight between water and the liquid measured B. Another term commonly used in conjunction with this type of system is "feed forward."
C. mass of substance measured with the density of the same substance
C. The controlled variable must always deviate from its set point before any corrective action is initiated by the controller.
D. buoyancy of an object in water with the buoyancy of the same object in the liquid being measured
D. In order for a system to fall under the category of closed loop control, there should be no adjustments required to be made manually by the operator.
Ans: D Ans: C
2994 Information from a data-logger can be helpful in determining the long term probability of machinery failure if you _____________.
2995 In pressure measurement, absolute pressure is defined as the difference in pressure between _________________.
A. evaluate only the latest logged data as this is the best indication of plant status
A. any two pressures measured with respect to a common reference
B. evaluate a series of readings to obtain operating trends B. atmospheric pressure and barometric pressure at a given point
C. monitor off limit conditions only when announced by an audible and visual signal
C. gage pressure and ambient atmospheric pressure
D. secure the machine under relatively steady state conditions D. a perfect vacuum and the total pressure at a given point
Ans: B Ans: D
2996 If the flow rate to a linear actuator is reduced by half of the original amount, the _____________.
2997 The characteristic of "offset" is inherent with which modeof control?
I. proportional control II. reset control A. pump discharge pressure will be reduced by a proportional amount A. I only
B. speed of the actuator will be reduced B. II only
C. speed of the actuator will be increased C. Both I and II
D. the actuator will move erratically D. Neither I nor II
Ans: B Ans: A
2998 The mandatory operating characteristic of a pure amplifieris the _______. I. form of the input and output energy must be the sameII.
ratio of the output change to input change must be a value greater than 1 (one)
2999 To avoid corrosion and/or oxidation of the element, a thermometer bulb is often protected by a "well" or casing. In addition to protecting the element, the "well" will also ________________.
A. I only A. cause consistently higher than actual readings
B. II only B. cause consistently lower than actual readings
C. Both I and II C. require a longer time for the element to reach thermal equilibrium
with the system being measured
D. Neither I nor II D. increase the sensitivity of the element
Ans: A Ans: C
3000 Reset control is considered to be the same as _________. I.
proportional speed floating control II. integral control
3001 A mechanical and/or hydraulic action preventing the over- correction of the fuel supply, while producing transient speed droop is called _______________.
A. I only A. stability
B. II only B. hunting
C. Both I and II C. compensation
D. Neither I nor II D. sensitivity
Ans: C Ans: C
3002 What is the value of the controlled variable that the automatic controller operates to maintain.
3003 At which of the following locations would a duplex pressure gage most likely be located?
A. Set point A. Fuel oil service pump discharge flange
B. Control point B. Fuel oil strainer
C. Deviation C. Fuel oil heater
D. Offset D. Fuel oil flow meter
Ans: B Ans: B
3004 Differential pressures can be measured with the use of a _____________.
3005 In order to accurately measure very low pressures, which of the instruments listed should be used?
A. diaphragm type gage A. Compound gage
B. pressure transducer B. Bourdon tube
C. manometer C. Manometer
D. all of the above D. Deadweight gage
Ans: D Ans: C
3006 A pneumercator is useful in measuring ____________________. 3007 The instrument used to indicate the level of a fluid in a tank is called a _______________.
A. relative humidity A. fluid meter
B. air pressure B. calorimeter
C. liquid levels in tanks C. viscosimeter
D. fluid pneumercations D. pneumercator
Ans: C Ans: D
3008 Main engine room control console alarms are to be of the self monitoring type, meaning that an open circuit to a particular alarm circuit will _____________.
3009 Which of the following alarms and instrumentation is not required for a vessel incorporating a controllable pitch propeller in its main propulsion system?
A. cause an alarm condition A. Pitch indicator
B. secure power to the indicator B. Low oil temperature
C. secure power to the monitored device C. High oil pressure
D. automatically reclose within 10 seconds D. Low oil pressure
Ans: A Ans: B
3010 A compound Bourdon tube type pressure gage is capable of measuring ______________.
3011 The instrument always used in conjunction with a salinometer is a _____________.
A. temperature and pressure A. pyrometer
B. wet bulb and dry bulb temperatures B. thermometer
C. humidity and temperature C. hygrometer
D. pressure and vacuum D. hydrometer
Ans: D Ans: B
3012 The control mode that is generally not used by itself is _________________.
3013 A closed loop pneumatic control system always operates with _____________.
A. reset control A. a fixed final control element position
B. integral control B. simple on/off control
C. derivative control C. no controller feedback
D. two position differential gap control D. feedback to the controller
Ans: C Ans: D
3014 While attempting to read a tank level indicator, the mercury column drops rapidly. This may indicate ____________.
3015 A pressure gage pointer responding sluggishly to changes in pressure, should be repaired by ______________.
A. a leak in the gage line A. tapping the gage housing lightly
B. free surface effect in the tank B. bending the needle to free the linkage
C. an improperly calibrated gage C. cleaning the residue from gear teeth
D. excess air in the balance chamber D. greasing the hair spring
Ans: A Ans: C
3016 A fuel oil tank pneumercator will give an inaccurate reading if the ____________.
3017 In an automation system, increasing or decreasing the loading pressure by a set amount is known as _____________.
A. pneumercator is recharged with the air supply open A. positioning B. pneumercator balance chamber bleed orifice is blocked by the oil
being measured
B. proportioning
C. pressure in the system is allowed to equalize C. biasing
D. operating cock is placed in the "vent" position when the system is not in use
D. controlling
Ans: B Ans: C
3018 Moisture and impurities can be removed from pneumatic systems by using ______________.
3019 A compound gage is used for measuring pressures both above and below _______________.
A. air intake heaters A. absolute pressure
B. desiccated suction strainers B. latent pressure
C. multi-orificed suction valves C. flow pressure
D. blowdown valves and filters D. atmospheric pressure
Ans: D Ans: D
3020 The type of gage most commonly used to measure pressure is the _____________.
3021 Temperature measurement is an indication of the ___________.
A. bimetallic type A. level of heat intensity
B. diaphragm type B. total heat of a substance
C. bourdon tube type C. rate of heat transfer from one substance to another
D. resistance-temperature type D. total heat contained in any closed energy system
Ans: C Ans: A
3022 In the operation of a proportional-plus-reset controller,the proportional action _________. I. opposes the reset action during decreasing error transients II. aids the reset action during increasing error transients
3023 Prior to testing the pyrometer circuit wiring for continuitywith a multimeter, you should disconnect the pyrometerbecause ____________.
A. I only A. the driving voltage of the meter batteries can damage the circuit
meter
B. II only B. the pyrometer total resistance can damage the ohmmeter
C. Both I and II C. the reactance of the pyrometer will give a false meter reading
D. Neither I nor II D. meter current running through the pyrometer will permanently
magnetize the pyrometer's pointer
Ans: C Ans: A
3024 A proportional band or range adjustment to a bourdon
tubepressure gage is accomplished by ___________. I. adjusting the effective moment arm length between the end of the bourdon tube and the quadrant gear fulcrum II. adjusting the pointer position
3025 A set point adjustment to a bourdon tube pressure gage isaccomplished by ___________. I. adjusting the effective moment arm length between the end of the bourdon tube and the quadrant gear fulcrum II. adjusting the pointer position relative to the
A. I only A. I only
B. II only B. II only
C. Both I and II C. Both I and II
D. Neither I nor II D. Neither I nor II
Ans: A Ans: B
3026 In checking the level of a tank, three pneumercator readings have been taken. If each reading is higher than the last, this indicates that _____________.
3027 Devices, such as a pressure gage, that are subject to continuous expansion and contraction are affected by hysteresis. This is a natural process that ___________.
A. excessive charging air was supplied A. allows a material to return to its exact original shape B. insufficient charging air has been supplied B. permits a resilient material to return to its almost original shape
C. the relief valve is sticking C. allows a resiliant material to resist permanent deformation D. the tubing between the tank and the gauge has a leak D. is directly related to a material's elastic limit
Ans: B Ans: B
3028 In an automation system, the effect of a control action sensed by a controller is known as _____________.
3029 A pneumercator is an instrument used to indicate __________.
A. command input A. air pressure in the diesel engine starting circuit
B. set point signal B. phosphates in boiler water
C. output C. tank fluid level
D. feedback D. micro ohms in condensate
Ans: D Ans: C
3030 The value of the controlled variable, which under any fixed set of conditions the automatic controller operates to maintain, is known as ____________.
3031 The steady state difference between the control point and the value of the controlled variable, corresponding with the set point, is known as _____________.
A. set point A. dead band
B. control point B. control point
C. deviation C. deviation
D. offset D. offset
Ans: B Ans: D
3032 A control action which produces a corrective signal relative to the length of time the controlled variable has been away from the set point, is known as ____________.
3033 While calibrating a bourdon tube pressure gage, all readings are found to be 0.7 kgs higher throughout its entire range. An adjustment should be made by ____________.
A. integral action A. increasing the sector to pivot point length
B. proportional action B. resetting the pointer on its shaft
C. rate action C. decreasing the sector to pivot point length
D. derivative action D. increase the set screw length
Ans: A Ans: B
3034 "Offset" is an inherent characteristic of which of the following types of control modes?
3035 The meat box temperature control circuit, as used in the ship service refrigeration system, is an example of ____________.
A. Two position A. two position control
B. Proportional B. single speed floating control
C. Reset C. proportional control
D. Rate D. reset control
Ans: B Ans: A
3036 A mode of control, whereby the position of the final control element is linearly proportional to the rate of change of the controlled variable, is called _______________________.
3037 When a controller is provided with reset rate adjustment, a change in this adjustment results in a change of the _______________.
A. reset control A. desired value of the proportionally controlled variable
B. integral control B. floating rate of the proportional-speed floating component
C. two position control C. value representing the readjusted controlled variable
D. derivative control D. desired prepositioned value of the controlled medium
Ans: D Ans: B
3038 The two most common gases used in pneumatic systems are _____________.
3039 When "reset" action is added to proportional action, the proportional action ______________.
A. compressed air and nitrogen A. aids the reset action during decreasing error transients
B. helium and nitrogen B. aids the reset action during increasing error transients
C. oxygen and hydrogen C. opposes the reset action during increasing error transients
D. oxygen and acetylene D. and reset action are completely independent of one another in the
controller operation
Ans: A Ans: B
3040 Automatic control valves for steam service require periodic maintenance inspections because they ___________.
3041 When "reset" action is added to proportional action _________________.
A. are subjected to high compressive stress A. the proportional action opposes the reset action during decreasing error transients
B. are subjected to a wide range of temperatures and pressures B. the proportional action opposes the reset action during increasing error transients
C. continuously throttle steam resulting in wire drawing and erosion of the valve
C. the proportional action assists the reset action during decreasing error transients
D. receive high pressure air from the pilot valve D. the proportional action and the reset action are completely independent of one another in the controller operation
Ans: C Ans: A
3042 When a controller with proportional position action is used to control a process, a load change will cause the controlled variable to stabilize at some value other than the set point value. The new point at which the controlled variable stabilizes is ca
3043 Which of the following control actions, when combined with proportional-position action, will eliminate manual repositioning of the set point for each load change to produce an automatic reset action?
A. offset A. Neutral band
B. deviation B. Floating action
C. control point C. Reciprocal action
D. load point D. Rate action
Ans: C Ans: B
3044 A rotameter, when used to indicate the rate of fluid flow in distilling plants, is essentially an area meter consisting of a
_____________.
3045 Double seated, pneumatically controlled, regulating valves exhibit good balancing characteristics essential for low-sensitivity applications because __________.
A. movable float riding on a rod centered in a tapered tube A. high pressure enters between the seats and creates equal, but opposing forces
B. piston uncovering a port whose opening is directly proportional to fluid flow
B. they employ a specially fabricated diaphragm
C. movable orifice plate venturi tube and high pressure tap C. the feedback control signals balance the opposing forces acting on the diaphragm
D. rotating vane transmitting nutating motion to a counter mechanism D. the special diaphragm motor spring resists pressure changes
Ans: A Ans: A
3046 The probable cause of erratic operation of a pneumatically controlled steam pressure reducing valve is ____________.
3047 A compound Bourdon tube gage is capable of measuring pressure and _______________.
A. the range spring has become weakened A. humidity
B. an incorrect loading pressure supplied to the power unit B. vacuum C. a partially restricted loading air pressure line C. temperature
D. a pinhole in the power diaphragm D. density
Ans: C Ans: B
3048 If you turn the handwheel clockwise of a spring-loaded, internal pilot, reducing valve, you will ____________.
3049 How may the response time for a thermometer using a protective well be reduced?
A. compress the adjusting spring against the diaphragm A. Fill the well with nitrogen.
B. release spring tension from the diaphragm B. Fill the well with water.
C. increase steam pressure to the reducing valve C. Drill small holes in the well.
C. increase steam pressure to the reducing valve C. Drill small holes in the well.