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What This Guide Helps With
Troubleshooting failed tightness tests or preoperational checks caused by circuit leaks, incorrect connections, flow sensors, humidifiers, or expiratory valve installation.
Step-by-Step Troubleshooting
1. Ensure Patient Safety First
Do not troubleshoot a failed preoperational check while the HAMILTON-C6 is supporting a patient.
- Notify respiratory therapy and the clinical team.
- Transfer the patient to another verified ventilator or approved ventilation method.
- Confirm that the replacement device passes its required checks and provides effective ventilation.
- Place the affected HAMILTON-C6 in Standby before changing circuit components.
Expected outcome: The patient is safely supported without relying on a ventilator that has not passed its preoperational check.
Hamilton specifies that the preoperational check should be completed after installing a new breathing circuit or flow sensor and before connecting the patient.
2. Identify Which Test Failed
Open System > Tests & calib, or select Preop check from the Standby window.
Determine whether the failure involves:
- Tightness test
- Flow sensor calibration
- O₂ sensor calibration
- CO₂ sensor calibration
- Startup self-test or alarm function
Record the red X, displayed message, and completion time.
Expected outcome: The failed portion of the preoperational check is clearly identified so troubleshooting can remain focused.
3. Confirm the Correct Test Setup
Verify that the ventilator is configured with the complete circuit intended for use, including:
- Inspiratory and expiratory limbs
- Flow sensor
- Expiratory valve set
- Filters
- Water traps
- Humidifier and chamber, when used
- CO₂ airway adapter, when used
Check that the selected patient group and circuit components are compatible.
Expected outcome: The ventilator is being tested with a complete, correctly configured breathing system.
If anything was missing or incorrectly installed, correct the setup and repeat the failed test. Stop if the check passes.
4. Inspect the Breathing Circuit for Leaks or Disconnections
Trace the circuit from the ventilator to the patient connection.
Check for:
- Loose inspiratory or expiratory connections
- Partially seated hoses
- Cracked tubing or connectors
- Open suction, nebulizer, sampling, or monitoring ports
- Loose water-trap caps
- Damaged filter housings
- Poorly seated humidifier chamber
- Unused ports without caps
- Incorrectly assembled coaxial circuit components
Push each connection fully into place without forcing it.
Expected outcome: The circuit is continuous, correctly assembled, and free of visible leakage points.
Repeat the tightness test. If it passes, document the loose or leaking connection and stop. Hamilton lists circuit disconnection, incorrect connection, and leakage as the first items to check after a failed preoperational test.
5. Perform the Tightness Test Correctly
Start the tightness test and follow the screen prompts exactly.
When instructed:
- Disconnect the circuit at the patient side of the flow sensor.
- Block the flow-sensor opening completely.
- Maintain a firm seal until the ventilator indicates that the test is finished.
Wear a clean glove and follow facility infection-control procedures when occluding the opening.
Expected outcome: The ventilator displays a green check and records the test completion date and time.
An incomplete seal, blocking the wrong location, or releasing the opening too early can produce an apparent failure.
6. Inspect the Flow Sensor and Tubing
Verify that:
- The correct Hamilton-compatible flow sensor is installed.
- The sensor is fully connected at the Y-piece or designated circuit position.
- Both flow-sensor tubing connections are secure.
- Tubing is not crossed, kinked, pinched, cracked, or disconnected.
- The sensor is dry and free of contamination.
- The sensor body is not visibly cracked or deformed.
Reconnect the sensor and tubing securely.
Expected outcome: The flow sensor and its pressure lines are correctly installed and intact.
Repeat the failed check. If it passes, stop. Hamilton identifies the flow sensor as the next component to inspect after the breathing circuit.
7. Repeat the Flow Sensor Calibration
Select Flow sensor under Tests & calib.
Follow each prompt:
- Attach the calibration adapter.
- Rotate the sensor and adapter 180 degrees as instructed.
- Wait for the ventilator to complete that portion of the calibration.
- Rotate the sensor back.
- Remove the calibration adapter when prompted.
Do not skip a prompt or rotate the sensor before instructed.
Expected outcome: A green check and updated completion time appear.
If calibration passes, reinstall the sensor in its normal operating position and stop.
8. Inspect and Reseat the Expiratory Valve Set
Remove the expiratory valve set only while the ventilator is out of patient use.
Check that:
- The silicone membrane is present.
- The membrane lies flat without folds, tears, warping, or contamination.
- The membrane’s metal plate faces upward and remains visible.
- The valve housing is clean and undamaged.
- The assembly is fully inserted and rotated clockwise into the locked position.
Reinstall the valve set carefully.
Expected outcome: The expiratory valve assembly is properly installed and seated.
Repeat the failed test. If the check passes, stop. Hamilton’s setup instructions specify correct membrane orientation and secure locking of the expiratory valve housing.
9. Isolate the Humidifier
When a humidifier is installed, temporarily configure the test circuit without it, using an approved setup.
Repeat the tightness test.
- If the test passes without the humidifier: Inspect the chamber, seals, adapters, temperature-probe ports, and circuit connections for leakage.
- If the test still fails: Continue troubleshooting the circuit, flow sensor, and expiratory valve.
Expected outcome: The humidifier is either identified or ruled out as the leakage source.
Hamilton specifically recommends repeating a failed preoperational test without the humidifier and checking the humidifier setup for leaks if the test then succeeds.
10. Substitute Known-Good External Components
Replace one component at a time with a compatible known-good item:
- Breathing circuit
- Flow sensor
- Expiratory valve set
- Humidifier chamber or associated adapter, when implicated
Repeat the failed test after each substitution. Avoid replacing several components simultaneously unless immediate isolation is not required.
Expected outcome: The defective external component is identified and the preoperational check passes.
Hamilton’s documented troubleshooting sequence recommends replacing the breathing circuit, flow sensor, and expiratory valve set before referring the ventilator for service.
11. Complete the Remaining Required Checks
Once the tightness test and flow-sensor calibration pass:
- Perform O₂ sensor calibration when indicated.
- Perform CO₂ sensor calibration when installed and required.
- Verify that the startup self-test produced the expected audible alarm.
- Confirm that all required tests display a green check.
- Perform a functional verification using an appropriate test lung before returning the device to service.
Expected outcome: The ventilator passes its preoperational checks and operates normally with the intended circuit configuration.
Do not return the ventilator to clinical use with an unresolved failed check. The C6 quick guide states that the ventilator should only be used after it passes all tests.
If the Problem Persists
If the preoperational or circuit test continues to fail after verifying the breathing circuit, flow sensor, expiratory valve set, humidifier setup, and known-good external components, the common external causes have been ruled out.
The fault may involve an internal pressure-measurement pathway, pneumatic component, valve-control system, or other internal ventilator condition.
The ventilator should be:
- Removed from service
- Labeled Out of Service
- Sent for authorized repair or bench evaluation
- Evaluated under the applicable Hamilton service procedure
Do not bypass the failed test or repeatedly recalibrate the device without addressing the underlying failure. Hamilton directs users to have the ventilator serviced when the check continues to fail after external components have been inspected or replaced.
Knowing when to stop and escalate is proper troubleshooting.
Clinical Use Tip
Never troubleshoot a circuit-test failure on an active patient. Move the patient to another verified ventilation method first, and perform testing only when the HAMILTON-C6 can remain safely in Standby.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Respiratory therapy reported that the HAMILTON-C6 failed the preoperational tightness test and displayed a red failure indicator."
Cause
What was observed during troubleshooting.
Example:
"Inspection found the expiratory valve membrane folded under the valve housing, preventing the valve set from sealing correctly."
Resolution
What action was taken.
Example:
"Reinstalled the membrane with the metal plate facing upward, secured the expiratory valve set, and completed the tightness test, flow-sensor calibration, and test-lung verification successfully."
Helpful Details to Include (If Known)
- Exact failed test or displayed message
- Patient group and circuit configuration
- Circuit type and manufacturer
- Humidifier installed or bypassed
- Flow sensor inspected or replaced
- Expiratory valve membrane condition
- Components substituted
- Test results before and after repair
- Audible startup alarm verified
- Test-lung functional check completed
- Unusual sounds, heat, odor, or leakage
- Final device status
Final Thought
A failed preoperational check should be approached as a system-level problem: protect the patient, verify the test method, inspect every external connection, isolate accessories, and substitute known-good components logically. Escalate the ventilator when the failure remains after external causes are ruled out, and document both the fault and final safety verification clearly.
That is successful troubleshooting.