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Manufacturer
Model
What This Guide Helps With
Unstable or mismatched readings caused by test setup, connections, environment, cycle conditions, sensing problems, or calibration-related issues.
Step-by-Step Troubleshooting
1. Remove Questionable Performance From Clinical Use
If temperature or pressure readings cannot be trusted, do not use the sterilizer for clinical loads until performance is verified.
Expected outcome: Sterilization is not performed with uncertain process measurements.
2. Confirm the Reported Reading Problem
Determine whether the display:
- Jumps or fluctuates
- Reads consistently high or low
- Differs from external test equipment
- Becomes abnormal only during certain phases
- Returns to normal when idle
Record the observed display behavior.
Expected outcome: The discrepancy is clearly characterized.
3. Verify the Test Equipment
Confirm the independent analyzer or test device:
- Is appropriate for sterilizer testing
- Is within current calibration status
- Is connected and positioned correctly
- Has undamaged leads, hoses, or probes
Expected outcome: The comparison instrument is suitable and reliable.
4. Verify Test Setup and Placement
Confirm pressure and temperature measurements are being taken using a manufacturer-supported or facility-approved method.
Incorrect probe or hose placement can create apparent discrepancies.
Expected outcome: Test setup is valid before the sterilizer is judged inaccurate.
5. Inspect Accessible Connections
Inspect accessible test ports, fittings, cables, sensor interfaces, and surrounding areas for:
- Moisture
- Loose connections
- Damage
- Contamination
- Kinks or leaks
Expected outcome: External connections are secure and intact.
6. Observe the Display During an Empty Test Cycle
Run an appropriate test cycle and watch for sudden changes, blank readings, unrealistic movement, or phase-specific instability.
Expected outcome: The display responds smoothly and consistently throughout the cycle.
7. Compare Against Approved Test Equipment
Record sterilizer readings and independent test readings at appropriate points during the test.
Do not alter calibration solely because of one inconsistent reading.
Expected outcome: The readings are either reasonably consistent under the approved procedure or a repeatable discrepancy is confirmed.
8. Repeat the Test to Rule Out Intermittent Setup Problems
If readings differ, repeat the test after rechecking the analyzer setup and accessible connections.
Expected outcome: A true equipment discrepancy is repeatable and not caused by test setup.
9. Do Not Make Unauthorized Calibration Adjustments
If a repeatable mismatch remains, do not enter restricted service menus or change calibration without proper Midmark service documentation, test equipment, and authorization.
Expected outcome: Calibration integrity is preserved and the issue is properly escalated.
10. Escalate Unreliable Temperature or Pressure Measurement
Remove the sterilizer from service if its displayed process values cannot be verified.
Expected outcome: The unit remains out of clinical use until sensing and calibration are evaluated.
If the Problem Persists
Common external causes such as analyzer accuracy, test setup, positioning, connections, and repeatability have been ruled out. Remaining causes may involve temperature sensing, pressure sensing, wiring, signal conditioning, calibration, or control electronics.
The sterilizer should be:
- Removed from service
- Labeled Out of Service
- Sent for repair or bench evaluation
- Evaluated using appropriate Midmark documentation and approved calibrated test equipment
- Calibrated or repaired only by qualified personnel
Return-to-service testing should verify temperature, pressure, and complete cycle operation using approved test methods.
Knowing when to stop external troubleshooting is proper troubleshooting.
Clinical Use Tip
Do not rely on cycle completion alone when the device's primary temperature or pressure indications are demonstrably unreliable.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Staff reported that the M11 pressure display fluctuated unexpectedly during sterilization."
Cause
What was observed during troubleshooting.
Example:
"Clinical Engineering reproduced the fluctuation and confirmed that the displayed pressure was inconsistent with calibrated test equipment."
Resolution
What action was taken.
Example:
"The sterilizer was removed from service and referred for qualified pressure-sensing evaluation before return-to-service testing."
Helpful Details to Include (If Known)
- Exact displayed values
- Phase where discrepancy occurred
- Test equipment used
- Test equipment calibration status
- Probe or hose placement
- Connection condition
- Whether discrepancy was repeatable
- Temperature comparison
- Pressure comparison
- Final device status
- Exact displayed values
- Phase where discrepancy occurred
- Test equipment used
- Test equipment calibration status
- Probe or hose placement
- Connection condition
- Whether discrepancy was repeatable
- Temperature comparison
- Pressure comparison
- Final device status
Final Thought
Verify the reference equipment and test setup before assuming a sensor failure, but remove the sterilizer from service whenever process measurements cannot be trusted.
That is successful troubleshooting.