Calibration Techniques & Procedures Flashcards
7 cards from real CCT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Calibration Techniques & Procedures flashcards as text
When calibrating a pressure gauge using a deadweight tester, the weights must be rotated slowly during the test primarily to:
Answer: Reduce friction effects in the piston-cylinder assembly
Rotating the weights minimizes piston friction, ensuring that the true hydraulic pressure equals the calculated weight force per unit area.
A thermocouple calibration procedure requires measuring the reference junction temperature because:
Answer: The EMF output depends on the temperature difference between measuring and reference junctions
Thermocouple EMF is a function of the temperature differential; without knowing the reference (cold) junction temperature, the measured junction temperature cannot be accurately determined.
During an as-found/as-left calibration record, the 'as-found' data is most critical for:
Answer: Determining whether the instrument drifted out of tolerance since the last calibration
As-found data captures the instrument's condition before adjustment, revealing drift and informing whether the calibration interval needs to be shortened.
Which calibration technique applies multiple increasing then decreasing input values to characterize both hysteresis and repeatability?
Answer: Up-down (bi-directional) calibration
Bi-directional calibration applies inputs in ascending and then descending order, exposing hysteresis as the difference between up-scale and down-scale readings at the same nominal input.
When calibrating a flow meter in situ, the preferred reference standard is often a master meter placed in series because:
Answer: Both meters experience identical flow conditions simultaneously
A master meter in series measures the same fluid at the same temperature, pressure, and flow rate, making direct comparison highly accurate without needing to replicate lab conditions.
A calibration tolerance of ±0.5% of full scale (FS) on a 0–100 psi gauge means the maximum allowable error at 25 psi is:
Answer: ±0.5 psi
Full-scale tolerance means the error band is fixed at ±0.5% × 100 psi = ±0.5 psi regardless of where in the range the reading is taken.
When performing a zero and span adjustment on a 4–20 mA transmitter, which adjustment should always be made first?
Answer: Zero, because span adjustments interact with the zero offset
Zero is adjusted first because span adjustments pivot around the zero point; correcting zero first minimizes the number of iterative adjustments needed.