Hamilton C6

Asset Type

Ventilator

Manufacturer

Hamilton

Model

C6

What This Guide Helps With

Troubleshooting failed flow-sensor calibration caused by incorrect sensor selection, loose tubing, circuit leaks, moisture, improper seating, or defective external components.

Step-by-Step Troubleshooting

1. Ensure Patient Safety First

Do not perform flow-sensor calibration while the ventilator is connected to a patient.

• Notify respiratory therapy and the clinical team.
• Transfer the patient to another verified ventilator or approved ventilation method.
• Provide manual ventilation when clinically required and performed by qualified personnel.
• Confirm adequate ventilation and monitoring before continuing.

Expected outcome: The patient is safely supported without relying on inaccurate flow, volume, or pressure measurements.

The C6 identifies missing or unusable flow-sensor calibration data as a high-priority condition.

2. Confirm the Reported Failure

Place the ventilator in Standby and open:

System > Tests & calib > Flow sensor

Determine whether:

• Calibration will not begin.
• The display repeatedly requests that the sensor be turned.
• Calibration completes with a red X.
• A “Flow sensor calibration needed” alarm remains active.
• The problem began after changing the circuit, flow sensor, humidifier, or expiratory valve.

Record the exact displayed message and whether the failure occurs every time.

Expected outcome: The failure condition is clearly identified before components are changed.

3. Verify the Selected Patient Group

Confirm that the installed flow sensor matches the selected patient group:

• Adult/pediatric flow sensor for the Adult/Ped patient group
• Neonatal/pediatric flow sensor when configured for neonatal use

A mismatch between the selected patient group and installed flow sensor will cause calibration to fail.

Expected outcome: The correct sensor type and patient category are selected.

If correcting the patient group resolves calibration, complete the remaining preoperational checks and stop.

4. Inspect the Flow Sensor

Remove the sensor from clinical use and inspect it externally for:

• Cracks or deformation
• Damaged connection nipples
• Contamination
• Condensate or medication residue
• A visibly damaged internal membrane
• Incorrect or incompatible sensor type

Do not insert tools or compressed air into the sensor.

When active humidification is used, accumulated water can interfere with proximal flow measurement. Hamilton recommends positioning the flow sensor at least 45 degrees relative to the floor to reduce water accumulation.

Expected outcome: The sensor is clean, dry, undamaged, and appropriate for the circuit.

5. Check the Flow-Sensor Tubing and Connections

Inspect both flow-sensor pressure tubes from the sensor to the ventilator.

Confirm that:

• Both tubes are fully attached.
• The tubes are connected to their corresponding flow-sensor ports.
• No tube is kinked, pinched, stretched, cracked, wet, or obstructed.
• The connector fittings are not loose or damaged.
• No accessories are pulling on the tubing.

Reseat each connection firmly without forcing it.

Expected outcome: Both differential-pressure pathways are open and securely connected.

If reseating the tubing resolves calibration, complete the preoperational check and stop.

6. Inspect the Breathing Circuit for Large Leaks

Check the complete test circuit between the ventilator and flow sensor, including:

• Inspiratory and expiratory limbs
• Y-piece
• Humidifier chamber and connections
• Water traps
• Filters and adapters
• Test lung connection
• Unused ports or open sampling connections

Reconnect any loose component and replace visibly damaged tubing or accessories.

Hamilton identifies circuit disconnections and large leaks, including leaks around the humidifier, as causes of failed flow-sensor calibration.

Expected outcome: The circuit is complete, correctly assembled, and free of obvious leaks.

7. Check the Expiratory Valve Set

Remove and reinstall the expiratory valve set according to the approved user-level setup procedure.

Confirm that:

• The valve set is fully seated.
• The membrane is correctly positioned.
• The membrane is not folded, torn, hardened, wet, or visibly contaminated.
• The valve housing is not cracked or obstructed.
• The assembly locks into place normally.

Improper seating of the flow sensor, expiratory valve set, or valve membrane can prevent successful calibration.

Expected outcome: The expiratory valve and membrane are properly assembled and seated.

8. Repeat the Calibration Correctly

With the patient disconnected:

• Assemble the complete breathing circuit and flow sensor.
• Select System > Tests & calib.
• Touch Flow sensor.
• Follow each screen prompt.
• Install the calibration adapter when instructed.
• Turn the flow sensor only when prompted.
• Return it to its starting orientation when prompted.
• Remove the adapter when instructed.
• Verify that a checkmark appears in the Flow Sensor checkbox.

A red X indicates unsuccessful calibration.

Expected outcome: Calibration completes with a checkmark.

If calibration passes, perform the tightness test and remaining required preoperational checks before returning the ventilator to service.

9. Substitute a Known-Good Flow Sensor

Install a compatible, known-good Hamilton flow sensor and repeat the calibration.

Use the correct calibration adapter when required.

Expected outcome:

• If calibration passes, the original flow sensor is defective or unsuitable.
• If calibration still fails, continue troubleshooting the valve and circuit.

Do not return the original sensor to use unless it passes inspection and calibration.

10. Substitute External Circuit Components

If the known-good sensor also fails, replace external components one at a time and repeat calibration after each change:

• Expiratory valve membrane
• Complete expiratory valve set
• Breathing circuit
• Humidifier chamber or associated circuit section, when installed

Hamilton’s specified sequence after persistent failure is to replace the flow sensor, expiratory valve membrane, and expiratory valve before requesting service.

Expected outcome: The defective external component is isolated.

11. Perform the Tightness Test and Functional Verification

After successful calibration:

• Run the breathing-circuit tightness test.
• Confirm that the test passes.
• Connect an appropriate test lung.
• Verify stable pressure, flow, and volume readings.
• Confirm that monitored tidal volume responds normally.
• Check for unexpected alarms.
• Complete the required preoperational check.

The C6 requires flow-sensor calibration and a circuit tightness test after installing a new or reprocessed circuit component.

Expected outcome: The ventilator passes calibration, tightness testing, and functional verification without alarms.

If the Problem Persists

If calibration continues to fail with:

• The correct patient group selected
• A known-good flow sensor
• Secure and unobstructed sensor tubing
• A verified breathing circuit
• A known-good expiratory valve membrane
• A known-good expiratory valve set

then common external causes have been ruled out. The problem may involve the internal differential-pressure measurement system, pneumatic pathway, sensor interface, or associated electronics.

The ventilator should be:

• Removed from service
• Labeled Out of Service
• Sent for authorized repair or bench evaluation

Do not perform internal pneumatic or board-level repairs without the appropriate Hamilton service documentation, training, and test equipment. Knowing when to stop and escalate is proper troubleshooting.

Clinical Use Tip

Never calibrate a flow sensor while the ventilator is connected to an active patient. Move the patient to another verified ventilator before disconnecting the circuit, replacing components, or running calibration tests.

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 displayed a red X during flow-sensor calibration and would not complete the preoperational check."

Cause

What was observed during troubleshooting.

Example:
"Inspection found condensate inside the adult/pediatric flow sensor and moisture within one flow-sensor pressure tube."

Resolution

What action was taken.

Example:
"Replaced the flow sensor and affected tubing, successfully completed flow-sensor calibration and circuit tightness testing, verified operation with a test lung, and returned the ventilator to service."

Helpful Details to Include (If Known)

• Patient group and sensor type verified
• Exact alarm or calibration message
• Calibration red X or checkmark observed
• Flow-sensor tubes inspected and reseated
• Moisture or contamination found
• Breathing circuit and humidifier checked
• Tightness-test result
• Known-good flow sensor tested
• Expiratory valve membrane or valve replaced
• Test-lung verification completed
• Final device status

Final Thought

Flow-sensor calibration failures should be approached by protecting the patient first, then checking sensor selection, tubing, leaks, moisture, and replaceable circuit components. Escalate when known-good external components do not correct the failure, and document each finding clearly.

That is successful troubleshooting.