CST PM & Calibration Schedules 2

Question 1

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?

Accepted Answer

±1 scale division

Answer

NIST HB 44 specifies that Class III devices must be within ±1 scale division at the time of inspection or calibration.

Question 2

A PM checklist for a floor scale specifies checking 'zero return after load removal.' What condition would indicate a failed zero return?

Accepted Answer

Display settles to a non-zero value beyond the zero-return tolerance

Answer

A failed zero return occurs when the indication does not return to within the accepted zero tolerance after a load is removed.

Question 3

Which calibration interval is most commonly recommended for a checkweigher used in a high-speed food packaging line operating 24/7?

Accepted Answer

Monthly or per shift

Answer

High-throughput checkweighers in continuous operation should be verified each shift or at minimum monthly to catch drift caused by vibration and wear.

Question 4

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?

Accepted Answer

Log the finding and replace the cable before returning to service

Answer

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.

Question 5

What is the primary purpose of performing an 'as-found' calibration check before making any adjustments during a PM visit?

Accepted Answer

To establish a baseline and document the scale's condition before adjustment

Answer

An as-found check documents how the scale was performing before the technician intervened, providing traceability and evidence of drift.

(CST) Certified Scale Technicians Practice Test

(CST) Certified Scale Technicians Practice Test

CST PM & Calibration Schedules 2