NCCER Flashcards
A technology bypassing conventional I/O by using direct communications between smart field devices and associated control processors is:
Fieldbus
Redundant controllers in a distributed control system reside:
As a hot standby at the central processor
The ultimate period method for tuning a controller was first proposed by:
Ziegler and Nichols
One method of oxygen analysis focuses on the:
Color properties of Oxygen
A piece of pipe has an AISI classification of A105, The major alloy is:
Carbon
Atmosphere testing must be conducted before entry into a confined space to check for:
Oxygen Content
Wish of the following contains information about chemicals found on a job site?
Material safety data sheet
Which of the following materials is selected when resistance to corrosion or high temperatures is required?
stainless steels
Which of the following is a type of gasket used in high-pressure systems?
metal Ring joint
Examples of inactive cutting oil include all of the following EXCEPT;
Sulfurized mineral oils
Which of the following thread sealant is MOST suitable for service temperatures of 500 to 700 degrees Fahrenheit?
Graphite Paste
A system installed to provide protection of equipment from line-to-ground fault damage is called;
Ground-fault circuit interrupter (GFCI)
Increasing the Carbon content in steel results in an increase in:
Hardness
The beveled edge of an orfice plate faces
Downstream
A bourdon tube is normally found inside a:
Pressure guage
A loop sheet contains all of the following information EXCEPT:
The calibration and specification
A temperature-measuring device that operates on the principle that electrical resistance changes with temperature is a
Resistance Thermal device (RTD)
capillary tubing with a bulb on the end is normally used on instruments that provide
temperature readings
A bourdon tube typically is used to measure
Pressure
what is the relationship of absolute pressure and gauge pressure
psia= psig + atmospheric pressure
process flow drawings(PFDs) are used to:
Aid in understanding the overall process
A material safety Data Sheet (MSDS) has all of the following sections EXCEPT:
Disposal Contractors
Which of the following tools should be used to remove old packing from the packing gland?
Packing extractor
Approximately what is the pressure, is psi, at the bottom of a 20-foot high tank filled with a fluid that has a specific gravity of 1.5?
13.0 psi
the drawing that shows how similar devices are to be installed and connected is an instrument:
Detail drawing
In a bubbler system measuring level from the bottom to the top of the vessel the dip tube is installed in a vessel with its open end:
Just above the bottom of the vessel
which wiring diagram does not show discrete conductors from end to end, but in a bundle?
Raceway diagram
when one controller is used to control two final elements it is known as:
Split range
In modulating control the first steps is the compute the error between controled variable and setpoint. The second step is to produce a(n):
Output signal
when used as a film between two surfaces, lubricants will reduce all of the following EXCEPT
Leakage
The letters “EL” on a blueprint stand for
Electronic line
Significant numbers are:
In front of the decimal
A proportional band of 100% is the equivalent to a gain of
1
what type of instrument loop uses feedback to correct change
Closed-loop
The component in an Instrument system that detects process change is the:
Primary element
A pressure transmitter connected across an orfice plate measures:
The differential pressure across the plate
What is the PRIMARY purpose for filing a pressure gauge case with glycerin?
Pulsation dampening
What part of a loop or an instrument first senses the value of a process variable, such as the level of liquid in a tank or the temperature of product?
Primary element
Where are the high and low sides connected when a differential pressure instrument is used to measure the level of a vessel with an operation/
The high side is connected to the bottom of the vessel, and the low side is vented to the atmosphere.
A control mode that either opens or closes a final elements is called
On/off
In order to take direct control over a process, the controller should be places in
Manual control
The operation modes of a loop controller are
Manual,Automatic, and cascade
Proportional controller is defined as a control
Mode in which the contoller produces a corrective signal that is proportional to the controlled variable’s percentage of deviation from the setpoint
where does the diaphram of springless, pneumatic actuator control valve use air pressure?
On both sides
An acutator on a regulating valve converts thermal,electrical, or fluid energy into electro-pneumatic energy
Mechanical energy
What type of control valve actutor is used MOST often?
pneumatic
A time delay is energized and 10 seconds pass before the contact in the relay are actuated. This is an example of
On-delay
A drawing that illustrates the physical components of a system, including its piping, valves, and instrumentation, is called:
P&ID
Which of the following is another name for synchronous time switch?
Dashpot Timer
Which of the following is controlled directly by an electrical relay?
Contacts
Pilot-operated regulators are prefered where what kind of pressure control is required?
precise
When a pressure switch is used as a low limit, deadband refers to the:
Distance from zero at which the switch returns to shelf state
An air dryer using a solid desiccant that does not liquefy is known as:
Absorptive
Which of the following INCREASES the inductance of a circuit?
Increasing number of turns in a coil
the capacity of a regulator when it has failed fully open is usually
greater than the regulating capacity
Why are air dryers an essential part of a pneumatic system used in instrumentation?
To eliminate moisture
Once ambient air is compressed then discharged from a compressor, its temperature is elevated and its moisture content is
low
In MOST cases, the cable shield will be attached
At one end
If all AND gates inputs are true, the output will be:
True
What is the digital element used to deny a burner ignition sequence if the fual gas pressure is abnormal, there is no air flow,or there is no pilot flame?
AND gate
To create a Nor gate, add inverter to the output of:
An AND gate
What would be the gain of a system with an input change of 20% and an output change of 10%
0.5
Which of the following describes SPAN?
The difference between 3 and 1
If the process is stable but controlling away from setpoint, what is needed to CORRECT the problem?
Decrease the derivitive
When bench calibrating a pressure transmitter, the instrument technician should apply
Air pressure in psi
Which tuning mode will cause the controller to generate an output proportional to the PV deviation from setpoint?
Reset
A pneumatic signal simulator can be used to calibrate
Pressure switches
When an electronic D/P cell is calibrated, the simulated inout pressure should be connected to the transmitter’s
High Side
The term “Span adjustment” refers to the adjustment of the
Range between the highest and lowest scale value of an instrument
When bench calibrating a temperature RTD transmitter, the instrument technician should apply
Resistance
As a general rule, before the smart communicator can be utilized, loop resistance MUST equal a MINIMUM of
250 ohms
Setting the relationship between the input signal and the response, or output, of a device is known as:
Calibration
Performing visual inspection to verify mechanical installation of loop components includes:
All components including process connection, primary, control elements, and wiring
When calibrating a flowmeter that uses a turbine sensing element, the instrument technician might use
A pulse source and milliamp
A bubbler is used as feedback in what type of system?
Pneumatic
Which turning mode will drive the PV to setpoint, thus eliminating offset?
Proportional
Ideally, functional verification of a loop is done through:
Process Simulation
The standard reference material used is resistance temperature detectors is
Platinum
The most widely used form of PLC programming is
Ladder logic
What communication protocol has become the most commonly used?
Hart (tr)
With a smaller intergral time, the output of a PID controller will be
Larger
In PLCs, how many possible stated do discrete inputs have?
Two
The term Topology is used with digital control systems to describe:
Configuration of data registers and processors
DCS stands for
Distributed Control System
In a test of the accuracy of a pneumatic comparator with a pressure guage, pressure readings of the test guage being tested are compared at a number of test points. Test points readings are made:
As the pressure is both increased and decreased
when a sensor is inserted in a thermowell, which of the following could safely improve response to temperature changes?
Antifreeze
What type of transducer converts the variable being measured into a voltage generated by a crystal when it is mechanically stressed?
Piezoelectric ( used in DP cells)
Changing the proportional band of a pneumatic controller changes:
The gain
A power supply component that reduces the ripple in the waveform is a:
Filter
What provides a warning when low and/or high limits of optimum range are being approached?
Absolute alarm points
A device that converts alternating current to direct current is called a:
Rectifier
The oil within the variable capacitor of a capacitance-type differential pressure transmitter is separated from the process by:
A sensing diaphragm
When a dip pipe (bubble) system is used for tank level measurement, the dip pipe is connected to:
The purge gas flow meter
What type of control has the most offset:
On-Off
Hydrostatic head level can not be measured with a:
resistance Probe
What is not necessary when zeroing or calibrating a magnetic flowmeter?
Calibration factor for the flow tube assembly
Closing high and low pressure tap block valves, venting low side to atmosphere, and connecting and applying a known calibration pressure to the high side is done to check:
Zero and span of a DP cell
Noise can affect instrument performance directly when it:
Is created by a ground loop
What primary element does not produce a differential pressure to measure flow:
Thermistor
What occurs if the temperature of the thermocouple measuring junction is lower than the reference junction?
The output voltage polarity is reversed
What temperature sensor produces an output resistance directly related to the temperature of the device?
RTD
Limit switch cams are usually found in:
Electric motor actuators
What is not a characteristic of positioners?
Allow for biasing the valve
Which of the following types of actuators responds to a pneumatic signal?
Diaphragm
When the percentage of flow through a valve equals the percentage of plug movement, a valve has:
Linear flow characteristic
To ensure the accuracy of a pneumatic controller throughout its range, you must precisely adjust:
Input
If a controller does not have full output when the manual adjustment is rotated to move the output pressure to full scale, the LEAST likely source of the problem would be:
proportional band setting
If nozzle back pressure does not decrease when it should, the most likely cause is :
Nozzle clogged with dirt
Input to the ___ bellows flows through an adjustable restriction.
Reset
Changing the proportional band of a controller changes:
The alignment of the controller
A low resistance reading from an underground signal lead connected to ground indicates a problem of:
A lead having an unwanted connection to ground
What can provide input/output isolation?
Optical coupling
The term used to describe multiple lines sending eight bits of data at a time is:
Serial Transmission
An oscilloscope waveform spans 5.5 vertical divisions. the vertical gain control is set at 2 volts/division/ the peak-to-peak voltage of the signal on the oscilloscope is:
11 volts
A breadbording area is:
Used to design or test electronic circuits
The digital test device that captures and displays a sequence of instructions from the program of a microcomputer is a:
Logic probe
A diamond on an instrumentation diagram encloses information about:
The power source
The density of a liquid affects the displacer’s:
bouyancy
What mode MUST the controller be in before any changes are made to the process variable?
manual
Bills of materials are found in:
general arrangement drawings
When bench calibrating a temperature RTD transmitter, the instrument technician should apply:
resistance
Before working on a de-energized circuit containing a capacitor, what must be done?
Discharge the capacitor
The MINIMUM value of the measured process range is considered to be:
3psi and 4mA
A solenoid valve is ofen used to:
Direct airflow that opens or closes an air-operated valve
Viscosity is not analyzed in:
the viscositron method
The process parameter that is selected for control is called the:
Controlled variable
Optimal gain is the MAXIMUM allowable value of gain in which the system is:
Stable
Carbon dioxide is produced commercially:
as a byproduct of manufacturing
The MOST reliable relay is an:
SSR
In modulating control, the first step is to compute the error between controlled variable and setpoint. the second step is to produce an:
Output signal
A dashpot timer relay:
is a type of pneumatic relay
A photosensor is a:
Silicone-controlled rectifier
Signal cable shields should be connected to ground at:
1 point in the signal path
What best determines the required torque for bolt tensioning?
Grade of bolt
Old packing should be replaces with new packing which is:
In kind
Atmosphere testing must be conducted before entry into a confined space to check for:
Oxygen Content
A DCS accepts 1 to 5-volt inputs. The transmitter outputs are 4-20 mA. What type of resistor should normally be installed in the analog input card?
250.0 ohms
Density is analyzed using all the following methods EXCEPT:
peptide
In a flash point analyzer the flash point of a fluid is detected by:
an unsustained flame
When selecting a regulator, chose the:
Overpressure protection that protects the regulator
A decreasing output with increasing input describes:
Reverse action
The basic element of the shift register is the:
Flip-flop circuit
The program that is permanently enterened into a PLC processor is called:
Firmware
Needle valves are used for
Low flow, high pressure drop, precision flow control
In a properly grounded system:
Excess voltage and current are rapidly directed to the earth
Pressure is expressed mathematically as:
Decreases when controller signal increases
Single-point grounding of signal cable shields:
Drains induced voltage from shields
A valve has linear-flow characteristics when the:
differential pressure corresponds directly to the valve stem position
A timely delay is energized and 10 seconds pass before the contacts in the relay are actuated. This is an example of:
ON-Delay
Which of the following is used to calibrate a DP transmitter?
Wally Box
Troubleshooting flow charts are most effective when:
Problems are identified
What instrument drawing shows an actual representation of a process operating sequence?
P&ID
The binary System is a base:
2 system
A common unit for volume of a gas is:
SCFM
Pressure switches are actuated by:
bellows, diaphragms, or bourdon tubes
The word “piezoelectric” refers to a certain class of crystals that produce an electric signal when they are mechanically:
Deformed
An orfice plate causes a pressure drop which can be measured to calculate:
Flow
Significant digits:
describe accuracy limits of a measurement or calculations
“proving” a loop involves:
Verifying desired interaction of loop components through simulation
The types of gaskets and gasket materils to be used on a project are listed in:
a section of the specifications
1 meter is:
39.3 inches
If the proportional band of a controller is adjusted to the MINIMUM possible value, the controller action is likely to be:
Excellent
The operation modes of a loop controller are:
Manual, automatic, and cascade
The span of an instrument with 24-36 psig is:
12psig
What valves aren’t used to regulate flow:
Gate
What tool should be used to remove old packing from the packing gland>
Packing extractor
Device used to check the integrity of tubing is the:
Wallace and Tieman calibrator
A controller receives an input signal from a:
Measuring element
On a field mounted controller, the set point is changed:
By the control room operator
What is a thermowell?
Protective device to house a thermocouple
What is the major cause of death from electrical shockl/
Heart fibrilation
The hydrostatic pressure created in a 10 foot tank with 8 feet water level is:
8psi
An example of a direct measurement indicator is a:
Pressure guage
To create a NOR gate, add an inverter to the output of:
an OR gate
Which of the following must be determined before selecting a pressure-reducing regulator?
Capacity required
Gaskets are usually specified for particular ranges of:
Temperature and pressure
What is the formula for pressure
P=F/A
A chromatograph is used to:
determine the chemical composition of a liquid or gas
What adjustments on a pressure transmitter sets the minimum range value
Zero
Proving a loop is a:
Simulated test run
When tuning a controller, increasing gain:
increases sensitivity
Which of the following materials is selected when resistance to corrosion or high temperastures is required?
Nickel Alloy
Loop testing involves simulation of the:
process variable
What describes span
The difference between 3 and 15
When a pressure switch is used as a low limit, deadband refers to the:
Distance from zero at which the switch returns to shelf state
A bubble isused as feedback in what type of system?
Pneumatic
A thermocouple is:
A temperature measuring device that produces a voltage as the temperature changes
A common operational feature of regulators is:
an input to provide the desired output
A flow meter BEST suited for suspended solids is a:
Target flow meter
DCS stands for
Digital communication system
Where would an instrument fitter find a P&ID number for a particular instrument?
in an instrument index
The hardness of a metal is reflected in its ability to resist:
Denting
What are not Instrument drawings?
pilot diagrams
What is not true about direct process recorders?
They aren’t used in a control center
DCS control functions take place in the:
Central computer
How is an annunciator used in a control room?
To signal alarms from a field location to the control room
A confined space is identified as:
having limited entry and exit
The setpoint on a controller is a specific value at which:
a process variable is to be maintained
The proper gasket flange-mounted pressure transmitter on a process pipeline should be selected from the:
Service index in the pipe specification book
When is the BEST time to document each loop chack for commissioning?
At the time each test is completed
In ladder logic, relay instructions are compromised of input contacts and output:
Contacts
Teflon tape used as a sealant should be wrapped:
In the same direction as the threads
What drawing shows the height, width, and depth of a particular installation?
Isometric drawing
A DCS work station may Not do:
Configure Logic
Which tuning mode will cause the controller to generate an output proportional to the PV deviation from setpoint?
Gain
An electrostatic precipitator is used to:
Remove particulates in a gas stream
