CCT Installation Procedures 5 — Questions and Answers
Question 1: After installing a new temperature transmitter in a HART loop, what must the technician configure first using a HART communicator before the transmitter will provide correct readings?
- Enable HART burst mode so the transmitter communicates continuously
- Configure the sensor type, range (LRV/URV), and engineering units to match the application (Correct answer)
- Set the damping to maximum to eliminate all noise in the output
- Download the latest firmware revision from the manufacturer's server
Correct answer: Configure the sensor type, range (LRV/URV), and engineering units to match the application
A HART transmitter shipped in factory default state must be configured with the correct sensor type, lower and upper range values, and units before it will provide application-accurate readings.
Question 2: When installing a turbine flow meter, what practice is essential to prevent bearing damage during initial start-up?
- Back-fill the meter with nitrogen before introducing process fluid
- Bring the process fluid up to flow slowly to allow the rotor to accelerate gradually rather than spinning up instantaneously (Correct answer)
- Install the meter with flow in the reverse direction initially to seat the bearings
- Pressurize the downstream side before the upstream side to prevent pressure shock
Correct answer: Bring the process fluid up to flow slowly to allow the rotor to accelerate gradually rather than spinning up instantaneously
Rapid flow introduction can cause the rotor to over-speed momentarily, exceeding bearing load ratings and damaging the precision bearings.
Question 3: A technician installs a pressure transmitter with a capillary-fill remote seal system. What phenomenon must be accounted for when the ambient temperature changes significantly?
- Changes in ambient temperature alter the dielectric constant of the fill fluid, shifting capacitance-based measurements
- Thermal expansion or contraction of the fill fluid changes the zero of the transmitter, requiring temperature compensation (Correct answer)
- Ambient temperature changes alter the transmitter's supply current requirements
- Lower ambient temperatures cause the remote seal diaphragm to become rigid and unresponsive
Correct answer: Thermal expansion or contraction of the fill fluid changes the zero of the transmitter, requiring temperature compensation
Fill fluid volume changes with temperature, generating a pressure shift at the transmitter that appears as a zero error unless the system is designed to compensate for it.
Question 4: What is the purpose of a calibration 'as-found / as-left' record when commissioning an instrument after installation?
- To document the instrument's purchase price and delivery date for asset tracking
- To record the instrument's error before and after adjustment, providing traceability and evidence of measurement quality (Correct answer)
- To list all spare parts consumed during the installation process
- To certify that the installer holds a valid calibration technician license
Correct answer: To record the instrument's error before and after adjustment, providing traceability and evidence of measurement quality
As-found data documents the initial calibration state, and as-left data confirms the final adjusted state; together they provide a traceable calibration record required by quality management systems.
Question 5: When mounting a vibrating fork (tuning fork) level switch in a vessel, which installation angle is generally NOT recommended by manufacturers?
- Horizontal mounting through the vessel side wall
- Angled downward at 45° from horizontal
- Vertical mounting from the top of the vessel looking down
- Mounting from the bottom of the vessel looking up (Correct answer)
Correct answer: Mounting from the bottom of the vessel looking up
Bottom-up mounting is generally not recommended because buildup of solids or heavy liquids on the forks can cause false actuation and the fork may be difficult to drain.
Question 6: During functional testing of a newly installed safety instrumented system (SIS) pressure switch, what activity must be performed to satisfy IEC 61511 commissioning requirements?
- Replacing the switch with a test-rated device before energizing the SIS loop
- Proof testing the switch end-to-end, verifying the final element (valve or trip) actuates at the setpoint and returns the SIF to safe state (Correct answer)
- Programming the SIS logic solver before performing any field wiring checks
- Obtaining a written waiver from the process hazard analysis (PHA) team before testing
Correct answer: Proof testing the switch end-to-end, verifying the final element (valve or trip) actuates at the setpoint and returns the SIF to safe state
IEC 61511 requires a complete proof test demonstrating that the safety instrumented function (SIF) responds correctly from sensor through logic solver to final element at the design setpoint.
Question 7: A technician is installing a pH electrode in an inline flow-through assembly. What installation parameter most directly affects the measurement response time?
- The ambient temperature outside the flow-through housing
- The flow velocity past the electrode sensing tip, which affects the rate of ion exchange at the glass membrane (Correct answer)
- The length of the cable between the electrode and the transmitter
- The supply voltage to the pH transmitter
Correct answer: The flow velocity past the electrode sensing tip, which affects the rate of ion exchange at the glass membrane
Adequate flow velocity across the pH glass membrane ensures fresh sample constantly contacts the electrode, minimizing response lag caused by boundary layer stagnation.
CCT Installation Procedures 5
After installing a new temperature transmitter in a HART loop, what must the technician configure first using a HART communicator before the transmitter will provide correct readings?