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What This Guide Helps With
Evaluate visible tube damage or contamination that may impair flow indication, structural integrity, cleanliness, or safe oxygen delivery.
Step-by-Step Troubleshooting
1. Protect the Patient and Remove the Suspect Flowmeter From Use
Do not continue oxygen therapy through a flowmeter with a cracked, severely clouded, contaminated, or otherwise compromised flow tube.
Transfer the patient to another verified oxygen source.
Expected outcome: Patient care continues through reliable equipment and the suspect flowmeter is isolated from clinical use.
2. Confirm the Visual Condition
Inspect the tube under good lighting and determine whether the issue is:
- A visible crack
- Surface scratching
- Clouding
- Internal residue
- Moisture
- Discoloration
- Foreign material
- Damage that obscures the float or scale
Expected outcome: The type and extent of the visible defect are clearly identified.
3. Inspect for Impact or Structural Damage
Examine the flowmeter body, tube supports, knob, inlet, and outlet for signs that the device was dropped or struck.
If a crack or structural damage is visible, do not pressurize the flowmeter merely to determine whether it still works.
Expected outcome: Structural damage is identified without unnecessarily placing the device under gas pressure.
If the tube is cracked, stop troubleshooting and remove the device from service.
4. Determine Whether the Contamination Is External
Inspect whether the observed material is on the outside surface or appears to be inside the flow tube.
Clean only external surfaces using facility-approved and manufacturer-compatible practices.
Do not introduce liquids, swabs, solvents, or tools into the flow tube unless specifically permitted by approved service documentation.
Expected outcome: External residue is removed safely, or internal contamination is identified for escalation.
5. Verify the Scale and Float Can Be Read Clearly
After permitted external cleaning, confirm that the scale markings and float position are clearly visible from the normal viewing position.
A tube that is too clouded or discolored to read reliably should not be used even if gas flow is present.
Expected outcome: The flow indication can be read clearly and unambiguously.
If visibility remains inadequate, remove the device from service.
6. Check for Moisture or Contamination From Downstream Accessories
Inspect attached humidifiers, tubing, and adapters for evidence that fluid may have migrated toward the flowmeter.
Correct or replace the external source of moisture or contamination before installing another flowmeter.
Expected outcome: The likely external source of contamination is identified and corrected where applicable.
7. Perform Functional Testing Only When the Tube Is Structurally Intact
If the tube has no crack or structural defect and the only issue was removable external contamination, use an appropriate test setup to verify:
- Free float movement
- Stable flow indication
- Normal adjustment
- Reliable shutoff
- No abnormal leakage
Expected outcome: The flowmeter operates normally and the indication remains clearly visible.
If all checks pass and no internal contamination exists, troubleshooting can stop.
8. Escalate Internal Contamination or Tube Damage
Remove the flowmeter from service if any of the following remain:
- Cracked tube
- Internal contamination
- Persistent clouding affecting readability
- Float sticking
- Moisture inside the tube
- Structural damage
- Uncertain flow indication
Do not perform unauthorized tube replacement, internal cleaning, or recalibration.
Expected outcome: A flowmeter with compromised structural integrity or indication is prevented from returning to service.
If the Problem Persists
External surface contamination and accessory-related causes have been evaluated.
Persistent clouding, internal residue, moisture, cracking, or float impairment may require component replacement, internal cleaning under approved procedures, calibration verification, or other service-level work.
The device should be:
- Removed from service
- Labeled Out of Service
- Sent for repair or bench evaluation
- Evaluated using appropriate manufacturer documentation and approved test equipment
- Repaired or configured only by qualified personnel
Before return to service, confirm structural integrity, clear visibility, free float movement, accurate flow performance, reliable shutoff, and leak-free connections.
Knowing when to stop external troubleshooting is proper troubleshooting.
Clinical Use Tip
If the float or scale cannot be read confidently, the flowmeter should not be relied upon for setting patient oxygen flow.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Clinical staff reported that the AirLife FlowMate tube appeared cloudy and the float was difficult to read."
Cause
What was observed during troubleshooting.
Example:
"Clinical Engineering found dried external residue covering the flow tube while the tube itself remained structurally intact and clear internally."
Resolution
What action was taken.
Example:
"The exterior was cleaned using approved practices, and clear visibility, free float movement, normal flow adjustment, shutoff, and functional performance were verified."
Helpful Details to Include (If Known)
- Crack, clouding, moisture, or contamination observed
- Whether contamination was internal or external
- Visibility of float and scale
- Evidence of impact
- Condition of tubing or humidifier
- Float movement
- Leakage observed
- Functional test results
- Cleaning performed
- Final device status
Final Thought
A clear, intact flow tube is necessary for reliable oxygen-flow indication. Distinguish removable external contamination from structural or internal problems, verify performance only when safe, and escalate any device whose integrity or readability remains uncertain.
That is successful troubleshooting.