On this page
Asset Type
Manufacturer
Model
What This Guide Helps With
This guide addresses situations where the Hamilton G5 ventilator displays flow sensor-related alarms or errors, such as:
- “Flow Sensor Error”
- Inaccurate tidal volume readings
- Inconsistent flow measurements
- Failure to pass pre-use calibration
The focus is on logical, external checks first — particularly sensor condition, circuit setup, moisture, and calibration — before assuming internal failure.
Step-by-Step Troubleshooting
1. Ensure Patient Safety First
- Transfer the patient to another ventilator if actively in use.
- Do not troubleshoot flow measurement issues while connected to a patient.
- Flow sensor errors directly affect delivered volume accuracy and patient safety.
2. Identify the Exact Alarm Message
- Document the specific wording of the alarm.
- Document when it occurs (startup, during ventilation, during calibration).
- Determine whether it is intermittent or constant.
This helps determine whether the issue is setup-related or hardware-related.
3. Inspect the Flow Sensor for Moisture or Contamination
The Hamilton G5 flow sensor is highly sensitive to:
- Condensation
- Secretions
- Nebulized medications
- Improper cleaning
- Remove the flow sensor from the circuit.
- Inspect visually for moisture or debris.
- If wet, dry completely per facility protocol.
- Replace with a known-good spare sensor if available.
Moisture is one of the most common causes of flow sensor alarms.
4. Verify Proper Sensor Orientation and Connection
- Confirm the flow sensor is installed in the correct direction.
- Ensure connectors are fully seated.
- Inspect the cable connection to the ventilator module.
- Check for bent pins or damaged connectors.
Improper orientation or loose connections can generate false readings or calibration failures.
5. Replace the Breathing Circuit
A compromised circuit can cause:
- Leaks
- Resistance changes
- Flow miscalculations
- Replace the entire patient circuit with a new, dry circuit.
- Avoid reusing circuits with heavy condensation.
- Ensure all connections are tight.
- Reattempt calibration after replacement.
6. Perform Flow Sensor Calibration
- Perform flow sensor calibration per facility procedure using the ventilator’s service or setup menu.
- Ensure no patient is connected during calibration.
- Ensure the circuit is dry and properly assembled.
If calibration fails repeatedly with multiple sensors and circuits, the issue may be internal.
7. Check for Excessive Condensation in the Expiratory Path
Inspect:
- Expiratory valve assembly
- Water traps
- Heated wire circuit function
Drain any water traps. Excess moisture can affect measurement accuracy and trigger alarms.
8. Inspect for Physical Damage
- Examine the sensor for cracks.
- Inspect for warping.
- Look for discoloration.
- Check for evidence of overheating.
Replace if any damage is present.
9. Power Cycle the Ventilator
- Turn the ventilator off properly.
- Wait 30 seconds.
- Restart and observe for recurrence.
Intermittent software-related sensor detection issues may clear with a restart.
If the Problem Persists
If multiple known-good sensors fail, multiple circuits fail, calibration repeatedly fails, or the alarm persists after moisture elimination, the likely cause may be:
- Internal flow measurement module issue
- Sensor interface board problem
- Internal wiring or signal processing fault
At this point:
- Remove the ventilator from service
- Label it “Out of Service”
- Send for bench evaluation or manufacturer-authorized repair
Knowing when to stop is proper troubleshooting.
Clinical Use Tip
Flow measurement accuracy directly affects tidal volume delivery and alarm safety.
Never attempt to “silence and monitor” a flow sensor error on an active patient. Always transition to a backup ventilator before troubleshooting.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
“Nursing reported ‘Flow Sensor Error’ alarm on Hamilton G5. Ventilator failed pre-use calibration.”
Cause
What was observed during troubleshooting.
Example:
“Flow sensor found with internal condensation. Circuit also contained excessive moisture.”
Resolution
What action was taken.
Example:
“Replaced flow sensor and breathing circuit. Performed successful flow sensor calibration. Ventilator passed operational check and returned to service.”
Helpful Details to Include
- Calibration pass/fail status
- Number of sensors tested
- Circuit replaced (Yes/No)
- Moisture present (Yes/No)
- Alarm message wording
- Final operational status
Final Thought
Flow sensor errors are often caused by moisture, contamination, or circuit issues rather than internal hardware failure. A systematic approach — dry, inspect, replace, calibrate — resolves most problems. When repeated calibration failures occur with known-good components, escalation is appropriate and protects patient safety. Thorough documentation supports trend tracking and equipment reliability.
That is successful troubleshooting.