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Manual Reference
3M Ranger Blood/Fluid Warming Unit, Model 245 and Ranger Irrigation Fluid Warming Unit, Model 247 Service Manual, document 34-8714-4407-0; Model 245 sections only. Also reviewed the Model 245 Operator's Manual.
Manufacturer Recommendation / AEM Status
The manufacturer-listed maintenance log states that the Model 245 operating temperature and over-temperature alerts should be tested at least every 6 months or according to institutional protocol. Cleaning is listed on an as-needed basis.
- Operating temperature: 41°C +/-1°C.
- First over-temperature alert: 43°C +/-1°C on the Ranger display, with audible alert, alert light, and alternating HI/temperature display.
- Secondary cutoff: confirm the hardware revision and current manufacturer procedure. The specification table lists 44°C for Rev. N and newer and 46°C for Rev. A through M; the included PM checklist describes a 46°C (+3°C, -2°C) test.
Temperature adjustment is not permitted. An out-of-specification unit requires removal from service and authorized support. All repair, calibration, and servicing are restricted by the manual to 3M Patient Warming or an authorized service technician.
If a facility performs this PM at a different interval or changes the listed activities, that should be handled under the facility's approved AEM program, risk assessment, maintenance history, and applicable regulatory requirements.
What This PM Procedure Covers
- Identification and hardware-revision confirmation.
- Exterior, cord, pole clamp, display, cassette slot, and accessory inspection.
- Cleaning of the exterior and heater plates as needed.
- Operating-temperature and over-temperature protection testing.
- Electrical safety testing when required by facility policy.
- Pass/fail decision and CMMS documentation.
Required Tools and Equipment
- Thermocouple with 0.005-inch lead or smaller; service-manual part number 90020.
- Calibrated thermocouple temperature monitor and aluminum tape.
- Ranger standard-flow blood/fluid warming set compatible with Model 245.
- Room-temperature saline or water.
- Phillips screwdriver for the manufacturer over-temperature test.
- Ranger cleaning tool and compatible nonabrasive cleaning solution when cleaning heater plates.
- Electrical safety analyzer when required by facility policy and facility-required PPE.
Step-by-Step PM Procedure
1. Identify the Unit and Revision
Action: Verify asset and serial numbers, Model 245 identity, voltage rating, hardware revision, location, and service history. Confirm it is not a Model 247 irrigation warmer.
Expected outcome: The device and applicable revision-specific cutoff criterion are positively identified.
2. Remove From Use and Clean Before Service
Action: Disconnect the unit from clinical use and unplug it. Treat the unit and accessories as potentially contaminated. Do not reuse a patient-care warming set for PM testing.
Expected outcome: The unit is safe to handle and the test setup presents no cross-contamination risk.
3. Inspect the Exterior and Mounting System
Action: Inspect the enclosure, handle, labels, display, power switch, alert indicator, cassette slot, bubble-trap holder, pole clamp, knob, equipotential stud, fasteners, and seams for damage, contamination, fluid intrusion, loose parts, or overheating. Verify secure clamp operation.
Expected outcome: The exterior and mounting system are intact, clean, and secure.
4. Inspect the Power Connection
Action: Inspect the specified detachable cord, plug, grounding pin, cord retainer, and power-entry module for cuts, exposed conductors, looseness, bent contacts, contamination, discoloration, or heat damage.
Expected outcome: The power connection is complete and free of unsafe damage.
5. Inspect and Clean the Cassette Slot
Action: Inspect the slot and heater-plate channels. Clean only as needed with the unplugged unit. Wet the Ranger cleaning tool with a nonabrasive solution, insert it from the rear, and pull it through the front. Rinse and repeat three times, then remove excess fluid. Do not immerse or sterilize the unit, use solvents or abrasives, or insert metallic tools.
Expected outcome: The cassette path and plates are clean, dry, undamaged, and unobstructed.
6. Secure the Unit for Testing
Action: Mount the warmer to an appropriate IV pole. The operator manual specifies a minimum 14-inch (35.6 cm) wheelbase radius and mounting height no higher than 44 inches (112 cm).
Expected outcome: The unit is stable and cannot tip during testing.
7. Prepare the Temperature-Test Cassette
Action: Use aluminum tape to attach the thermocouple to the top surface of a compatible standard-flow cassette in the service-manual position. Insert the cassette. Prime with room-temperature saline or water through the inlet tube, not the outlet, drain at least 2 mL as shown by the manufacturer, and close the patient line with the white clamp.
Expected outcome: The cassette is correctly oriented, primed, and instrumented.
8. Verify Power-Up and Warm-Up
Action: Connect to a grounded outlet, turn the unit on, observe the display and alert indicator, and allow a 5-minute warm-up.
Expected outcome: The unit initializes and reaches set point without an unresolved error, HI, or LO condition.
9. Verify Operating Temperature
Action: Record the Ranger display and calibrated thermocouple readings after warm-up. Account for the test instrument's stated accuracy under facility policy.
Expected outcome: Operating temperature is 41°C +/-1°C. Do not adjust an out-of-specification unit; remove it from service.
10. Verify the First Over-Temperature Alert
Action: Perform this technique-sensitive test only after reading the complete manufacturer procedure. Loosen the bottom over-temperature test screw until the microswitch opens with a slight click, then loosen another one-half turn. At 43°C +/-1°C on the display, verify the audible alert, alert light, and alternating HI/temperature display.
Expected outcome: All first-stage warning indications activate at the listed point.
11. Verify the Secondary Cutoff
Action: Monitor the thermocouple and listen or feel for the power relay to open. Apply the current manufacturer criterion for the identified hardware revision. Record relay cutoff and peak temperature within one minute.
Expected outcome: Heater power is removed at the applicable revision-specific limit, while the audible alert, light, and alternating display remain active.
Immediate stop: If temperature exceeds the applicable manufacturer maximum, tighten the screw, unplug the unit, run cold fluid through the cassette, remove the unit from service, and contact authorized support. The older 46°C checklist specifies stopping above 49°C.
12. Verify the Latched Safety Response
Action: If included in the current revision-specific procedure, momentarily switch the unit off and back on after secondary protection activates.
Expected outcome: The secondary alert remains latched through the switch cycle.
13. Restore and Cool the Unit
Action: Securely tighten the test screw, turn the warmer off, unplug it, and allow it to cool. The manual estimates 20-30 minutes.
Expected outcome: The test mechanism is restored, the alert ceases after disconnection, and the unit cools normally.
14. Complete Electrical Safety Testing
Action: When required by policy, test protective-earth resistance and touch/chassis leakage as a Class I, Type BF device. The manual identifies the IV-pole clamp screw threads or rear equipotential stud as grounding test points.
Expected outcome: Results meet applicable facility criteria.
15. Final Inspection and Return to Service
Action: Dispose of the single-use test set. Confirm the slot is empty and dry, the test screw is secure, all parts are intact, and no error or alert remains. Document results.
Expected outcome: The unit is complete, clean, within specification, and ready for service.
Electrical Safety Testing
The Model 245 is Class I, Type BF equipment. The manual states that it meets UL/IEC 60601-1 leakage-current requirements but does not provide a routine field leakage limit. Use the facility's approved procedure and limits.
Ground resistance measured in ohms, expected ≤ 0.5 Ω or facility/NFPA 99 criteria if different.
Touch/chassis leakage measured in microamps:
Facility limit used =
Result =
Pass / Fail =
Pass / Fail Criteria
PM Pass Criteria
- Exterior, mounting hardware, power connection, controls, indicators, slot, and plates pass inspection.
- The unit is clean, dry, and free of obstruction or fluid intrusion.
- Power-up and warm-up complete normally.
- Operating temperature is 41°C +/-1°C.
- The first alert activates at 43°C +/-1°C with all listed indications.
- Secondary protection and latching meet the current criterion for the identified revision.
- The test screw is restored and electrical-safety results pass when applicable.
Remove From Service Criteria
- Identity or revision cannot be confirmed well enough to select the correct test.
- Unsafe damage, contamination, fluid intrusion, obstruction, or an unresolved error is present.
- Operating temperature or either over-temperature protection stage fails.
- Peak temperature exceeds the applicable manufacturer maximum.
- Ground resistance or leakage fails the facility limit.
- Internal repair, calibration, or unauthorized adjustment is needed.
Copy/Paste CMMS Work Order Procedure
Use the manufacturer service manual, facility policy, and approved AEM program to determine the final PM interval and return-to-service requirements.