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Asset Type
Manufacturer
Model
Models Covered
Precision Medical 1MFA, 4MFA, 5MFA, 6MFA, and 8MFA Series medical gas flowmeters when document 503349 Rev. 14 applies. This site record is for oxygen flowmeters; the same OEM test method may be used for an Air-labeled variant only with its exact gas source, analyzer setting, and model markings. Identify the full part number, gas, scale, inlet pressure, connection, accessories, glass/polycarbonate tube, and MR label before testing. Dial 7MFA and other designs require their own documentation.
Manual Reference
Precision Medical Flowmeter User Manual, document 503349 Rev. 14; Precision Medical Recommended Testing for Verifying Device Performance, 2026, page 11; and Precision Medical Flowmeter Product Catalog, 2026. The flow tube/body markings control if they differ from this summary.
Manufacturer Recommendation / AEM Status
Precision Medical requires visual inspection before each use and states not to use a damaged flowmeter. Its recommended performance-testing document leaves the test interval to the healthcare provider or dealer. The facility must assign and justify the scheduled interval under its maintenance program; this procedure does not invent an OEM annual interval.
Perform the complete applicable three-point accuracy test after repair, cleaning that could affect operation, a leak or accuracy complaint, impact, float sticking, or other performance-affecting service. The 8MFA has no serviceable parts and must not be repaired internally.
What This PM Procedure Covers
- Exact model, gas, scale/range, inlet pressure, fitting, restrictor, accessories, tube material, MR marking, and service history
- Body, flow tube, float ball, scale, labels, control valve, source connection, outlet, and accessories
- OFF leakage, float return-to-zero, smooth control, vertical operation, and maximum flush function
- Calibrated low/middle/high flow testing using the correct gas-specific analyzer setting
- Scale-specific OEM accuracy limits from 0-200 cc/min through 0-70 L/min
- Cleaning status, final restoration, pass/fail, and CMMS documentation
Required Tools and Equipment
- Current Precision Medical manual and Recommended Testing sheet for the exact model
- Correct clean, dry medical oxygen source at the inlet pressure marked on the flow tube/body
- Calibrated flow analyzer covering the unit's full calibrated scale and configured for oxygen
- Correct gas-indexed source fitting, outlet fitting, tubing, caps, adapters, and oxygen-compatible leak detector
- Stable vertical test fixture outside the MR controlled zone unless the entire setup is approved for that zone
- Approved exterior disinfectant wipes, lint-free towels, gloves, and facility oxygen-safety supplies
- Exact authorized repair parts for serviceable 1MFA/4MFA/5MFA/6MFA units; no internal parts for 8MFA
Step-by-Step PM Procedure
1. Identify the Exact Flowmeter
Action: Record asset tag, full part number/series, serial or lot identifier, gas, scale and units, inlet pressure, source connection, outlet, power-take-off or branch accessories, restrictor labeling, tube material, and MR Conditional label. Match the unit to document 503349 Rev. 14.
Expected outcome: The equipment and CMMS record agree, and the correct test gas, pressure, scale, and tolerance are known. Stop if the model is outside the manual's 1MFA/4MFA/5MFA/6MFA/8MFA scope.
2. Review History and Apply Oxygen Safety
Action: Review weak/no flow, incorrect delivery, leakage, sticking float, seized valve, impact, contamination, or prior repair. Remove the unit from patient use. Keep oil, grease, organic lubricant, flames, smoking, combustible materials, and incompatible leak solutions away from oxygen equipment.
Expected outcome: Service concerns are documented and the bench area, tools, and hands are clean and suitable for oxygen service.
3. Clean and Dry the Exterior
Action: Disconnect all gas connections. Clean external surfaces with Super Sani-Cloth germicidal wipes or the current equivalent approved by Precision Medical/facility policy, allow complete air drying, and repeat if visible contamination remains. Do not autoclave, use EtO, clean with aromatic hydrocarbons, or immerse the flowmeter.
Expected outcome: The exterior is visibly clean, fully dry, residue-free, and has no evidence of fluid entry.
4. Inspect Body, Tube, Scale, Labels, and Fittings
Action: Inspect the body, housing, backplate, flow tube, float ball, scale/graduations, gas and pressure markings, knob, valve, inlet, outlet, threads, O-rings/seals, adapters, PTO, Y-block/T-branch, humidifier connection, and cannula/tubing accessories. Look for cracks, chipped glass, clouding, discoloration, debris, corrosion, loose or cross-threaded fittings, blocked passages, missing/illegible labels, or contamination.
Expected outcome: All components are complete, readable, clean, secure, unobstructed, and gas-specific. Any damaged glass tube, leaking body, unreadable scale/gas label, or questionable oxygen cleanliness is a failure.
5. Verify MR Conditions When Labeled
Action: For an MR-labeled 1MFA or 8MFA only, verify the label remains present, the unit is securely attached to a wall gas outlet, and any serviced/replaced fitting retains MR Conditional status. The Rev. 14 manual identifies use near a 1.5 T MR system but not inside the scanner bore. Follow the MRI manufacturer and facility MR policy when stricter.
Expected outcome: The MR-labeled unit and its fittings retain the documented configuration and are not used or tested in an unapproved MR location.
6. Verify OFF, Zero, and Control Movement
Action: Place the flowmeter upright and vertical. Turn the knob clockwise gently to OFF without overtightening. With no gas connected, confirm the float ball rests fully at the bottom. Move the knob through its usable range and return to OFF; do not force the valve.
Expected outcome: The float rests at zero, the control turns smoothly without seizure, looseness, or binding, and the valve is not damaged by overtightening.
7. Connect the Correct Gas and Test Equipment
Action: Confirm the source gas and pressure match the flow tube/body. Connect using the correct oxygen-indexed fitting, verify a secure leak-free connection with oxygen-compatible leak detector, and attach the calibrated flow analyzer to the outlet. Set the analyzer to oxygen. Remove downstream accessories during accuracy testing unless the exact OEM procedure requires them.
Expected outcome: The flowmeter is vertical, connected to the correct gas/pressure, leak-free, and measured with a calibrated analyzer using the correct gas compensation.
8. Verify Shutoff and Float Response
Action: With the source pressurized and the knob in OFF, verify the float remains at the bottom and analyzer flow is zero or within the analyzer/facility's justified no-flow threshold. Slowly open counterclockwise and close clockwise while watching the float and analyzer.
Expected outcome: OFF does not leak clinically significant flow; the float rises and falls smoothly without sticking, jumping, lagging, or scraping; and flow changes predictably with the knob.
9. Select Three Accuracy Test Points
Action: Divide the calibrated scale into approximately equal low, middle, and high divisions and choose labeled graduation lines in each division. Do not use flush flow or a value beyond the last calibrated line as an accuracy point. For each point, align the center of the float ball with the selected line, allow stabilization, record the analyzer reading, and apply the exact scale-specific tolerance below.
Expected outcome: Three traceable labeled points cover the usable calibrated range, and each is evaluated against the correct OEM tolerance.
10. Apply the OEM Accuracy Limit
Action: Use the tolerance for the identified range and test point:
- 0-200 cc/min: 0-100 cc/min ±10 cc/min; 101-200 cc/min ±14 cc/min
- 0-1 L/min: ±0.05 L/min
- 0-3.5 L/min: ±0.15 L/min
- 0-5 L/min: ±0.20 L/min
- 0-6 L/min: ±0.50 L/min
- 0-8 L/min: ±0.25 L/min
- 0-15 L/min: 0-5 L/min ±0.25 L/min; 6-15 L/min ±0.50 L/min
- 0-26 L/min: 2-4 L/min ±0.50 L/min; 5-26 L/min ±10% of reading
- 3-35 L/min: 3-4 L/min ±0.50 L/min; 5-35 L/min ±10% of reading
- 0-70 L/min: ±10% of reading
Expected outcome: Low, middle, and high analyzer readings all fall within the applicable tolerance. Record the selected line, expected value, limit, and actual value rather than only “pass.”
11. Control Temperature and Pressure Effects
Action: Test at the inlet pressure marked on the unit and, when practical, near the 70°F (21°C) calibration condition. Document ambient temperature and pressure when they could affect interpretation. Rev. 14 states the temperature effect is standard accuracy +7.3% at 32°F (0°C) and -3.0% at 104°F (40°C); do not silently widen limits without an approved calculation/procedure.
Expected outcome: Test conditions support a valid comparison, or the result is deferred/repeated under appropriate conditions.
12. Verify Flush Flow and Accessory Operation
Action: Turn fully counterclockwise and verify flow rises beyond the highest calibrated graduation into the labeled flush region without binding. Treat flush as uncalibrated and do not assign a value unless the unit's label/manual provides one. Return to a calibrated setting, reinstall each approved accessory, and verify secure engagement, no leak, and usable flow. Account for downstream resistance when interpreting the indicated flow.
Expected outcome: Flush operation is available without control damage, accessories are secure and leak-free, and the flowmeter returns to stable regulated operation.
13. Repair or Replace Under Model Rules
Action: Qualified personnel may use current Precision Medical parts/instructions for serviceable 1MFA, 4MFA, 5MFA, or 6MFA configurations and must repeat the complete leak, zero, function, and three-point accuracy test afterward. Do not attempt internal repair of an 8MFA; replace or return it through the approved process.
Expected outcome: Only authorized service is performed, gas and MR indexing are preserved, and every repaired unit passes full post-service verification.
14. Restore and Document
Action: Return the knob gently to OFF, disconnect the source safely, remove test adapters, reinstall approved accessories, and complete a final cleanliness, label, zero, fitting, and knob check. Record analyzer ID/calibration status, gas, pressure, temperature, three points and tolerances, leak/float/flush findings, parts, corrective action, and disposition.
Expected outcome: The flowmeter is clean, complete, in OFF, traceable, and either returned to service or clearly quarantined.
Electrical Safety Testing
Not applicable. These flowmeters are pneumatic medical-gas devices without AC mains power, protective earth, or an electrical patient applied part. Document electrical safety as N/A - pneumatic device, not as a passed leakage-current test. Gas-specific connection, oxygen cleanliness, leakage, and flow accuracy are the applicable safety controls.
Pass / Fail Criteria
Pass
- Exact model, gas, range, units, inlet pressure, fitting, accessories, tube type, and MR status are documented
- Flowmeter is clean, dry, oxygen-safe, undamaged, fully labeled, upright, and leak-free
- Float rests at zero in OFF and moves smoothly with predictable control response
- Low, middle, and high points all meet the exact OEM tolerance for the marked scale
- Flush function operates beyond the calibrated range without being reported as a calibrated value
- Accessories are secure and functional, authorized repair rules are followed, and all readings/test-equipment data are documented
Remove From Service
- Wrong/unknown gas, pressure, range, fitting, model/manual, MR status, or test procedure
- Cracked/chipped tube, unreadable scale or gas label, contamination, oxygen-incompatible material, loose/cross-threaded fitting, blocked passage, or leak
- Float does not rest at zero, sticks, jumps, lags, or cannot be read reliably
- Valve will not shut off, turns poorly, cannot regulate smoothly, or any accuracy point exceeds the applicable OEM limit
- An 8MFA requires internal repair, or a repaired unit has not passed complete post-service verification
Copy/Paste CMMS Work Order Procedure
Use the exact current Precision Medical documentation and markings for the complete model. Never use oil or grease, never substitute air for oxygen during an oxygen-flowmeter accuracy test, never report flush flow as calibrated flow, and never attempt internal repair of an 8MFA.