PM & Calibration Schedules Flashcards
7 cards from real CST practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 PM & Calibration Schedules flashcards as text
Under NIST Handbook 44, what is the maximum permissible error (MPE) tolerance class typically applied during a periodic calibration of a Class III commercial scale?
Answer: ±1 scale division
NIST HB 44 specifies that Class III devices must be within ±1 scale division at the time of inspection or calibration.
A PM checklist for a floor scale specifies checking 'zero return after load removal.' What condition would indicate a failed zero return?
Answer: Display settles to a non-zero value beyond the zero-return tolerance
A failed zero return occurs when the indication does not return to within the accepted zero tolerance after a load is removed.
Which calibration interval is most commonly recommended for a checkweigher used in a high-speed food packaging line operating 24/7?
Answer: Monthly or per shift
High-throughput checkweighers in continuous operation should be verified each shift or at minimum monthly to catch drift caused by vibration and wear.
During a scheduled PM on a load cell–based tank scale, a technician notices the cable jacket is cracked near the junction box. What is the correct action?
Answer: Log the finding and replace the cable before returning to service
A cracked cable jacket exposes signal wires to moisture and EMI, which can corrupt readings; the cable must be replaced before the scale is returned to service.
What is the primary purpose of performing an 'as-found' calibration check before making any adjustments during a PM visit?
Answer: To establish a baseline and document the scale's condition before adjustment
An as-found check documents how the scale was performing before the technician intervened, providing traceability and evidence of drift.
A calibration certificate for test weights used in a PM must include which of the following to maintain traceability?
Answer: A reference to national or international measurement standards
Traceability requires that calibration certificates reference an unbroken chain back to national or international standards such as NIST.
An indicator's internal reference calibration (span calibration) is adjusted using certified test weights. After adjustment, the span error at full capacity is –0.3 divisions. What should the technician do?
Answer: Accept the result if it is within MPE for the device class
A span error within the maximum permissible error for the applicable device class is acceptable and does not require further adjustment.