CMLA Equipment Maintenance 5 — Questions and Answers
Question 1: Which standard is most commonly referenced for biological safety cabinet certification and testing in the United States?
- NSF/ANSI 49 (Correct answer)
- OSHA 29 CFR 1910.1030
- CAP checklist COM.01600
- ISO 15189
Correct answer: NSF/ANSI 49
NSF/ANSI 49 is the U.S. standard governing the design, construction, and field testing of Class II biosafety cabinets.
Question 2: What does a 'delta check' failure on a patient result indicate in the context of analyzer maintenance?
- The current result differs significantly from the patient's previous result, suggesting a possible specimen or instrument error (Correct answer)
- The instrument exceeded its maximum daily test count
- The control material is out of the acceptable range
- The patient sample was hemolyzed
Correct answer: The current result differs significantly from the patient's previous result, suggesting a possible specimen or instrument error
Delta checks compare sequential patient results to flag unlikely changes that may indicate a mislabeled specimen, wrong patient, or instrument malfunction.
Question 3: A laboratory balance fails its linearity check with a certified weight set. What is the appropriate next step?
- Remove the balance from service, recalibrate or send for repair, and recheck with certified weights before returning to use (Correct answer)
- Use the balance only for non-critical weighing tasks until the next scheduled PM
- Document the failure and continue use if results are within 5% of expected
- Request a new certified weight set, assuming the weights are the problem
Correct answer: Remove the balance from service, recalibrate or send for repair, and recheck with certified weights before returning to use
A failed linearity check means the balance cannot be trusted for accurate measurement and must be removed from service until verified.
Question 4: What is the purpose of running a 'carry-over' test on an automated chemistry analyzer?
- To detect contamination of a low-concentration sample by a preceding high-concentration sample in the same analyte (Correct answer)
- To verify that the analyzer can process multiple analytes simultaneously
- To check reagent stability over an extended run
- To confirm that QC results remain within range across different operators
Correct answer: To detect contamination of a low-concentration sample by a preceding high-concentration sample in the same analyte
Carry-over tests use alternating high and low samples to quantify how much residual analyte from a high sample contaminates the next low sample.
Question 5: Which document specifies the manufacturer's recommended maintenance schedule for a laboratory instrument?
- The instrument's operator or service manual (Correct answer)
- The laboratory's standard operating procedure (SOP) only
- The accreditation body's checklist
- The institution's infection control policy
Correct answer: The instrument's operator or service manual
The operator or service manual provided by the manufacturer contains the recommended PM schedule, cleaning procedures, and part replacement intervals.
Question 6: What is the primary risk of operating a centrifuge with a rotor that has exceeded its manufacturer-specified maximum run count?
- Metal fatigue can cause rotor failure or explosion during high-speed operation (Correct answer)
- Centrifugation time will automatically increase
- The timer display will become inaccurate
- Samples will be under-centrifuged, affecting separation quality only
Correct answer: Metal fatigue can cause rotor failure or explosion during high-speed operation
Rotors have finite fatigue life; exceeding the maximum run count increases the risk of catastrophic rotor failure, which can be fatal.
Question 7: If a laboratory freezer alarm activates at 3 AM, what is the most appropriate first action for the on-call staff member?
- Check the actual freezer temperature and assess whether specimens must be moved to a backup unit (Correct answer)
- Silence the alarm and check the unit the next morning
- Discard all specimens in the freezer as a precaution
- Call the manufacturer's service line before checking the freezer temperature
Correct answer: Check the actual freezer temperature and assess whether specimens must be moved to a backup unit
Verifying the actual temperature first determines whether a true excursion has occurred and guides the decision to relocate specimens.
CMLA Equipment Maintenance 5
Which standard is most commonly referenced for biological safety cabinet certification and testing in the United States?