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Asset Type
Manufacturer
Model
Models Covered
Blanketrol III, Model 233 only. Do not apply the internal test-point, alarm-reset, water, or acceptance instructions on this page to earlier Blanketrol models without their model-specific manual.
Manual Reference
Gentherm Medical Blanketrol III Model 233 Operation and Technical Manual 57299, Revision I (2022). Cincinnati Sub-Zero/CSZ branding may appear on installed equipment; Gentherm publishes the current official documentation.
Manufacturer Recommendation / AEM Status
The Model 233 manual requires the listed preventive-maintenance procedures quarterly or when the 500-hour PM notification appears, whichever occurs first. The manufacturer schedule includes reservoir service, water-circuit disinfection, water-filter replacement, condenser/grill cleaning, external cleaning, blanket/hose care, flow and pressure checks, leakage current, high- and low-temperature protection, and temperature accuracy.
After maintenance, a qualified medical-equipment service technician, CBET, or clinical engineer resets the HOURS UNTIL SERVICE counter to 500 using the manufacturer key sequence. Internal access, system testing, calibration, and repair are service activities for qualified personnel. Do not extend the stated interval without a documented, approved AEM assessment.
What This PM Procedure Covers
- Identity, history, cabinet, labels, casters, cord, controls, indicators, quick-disconnects, hoses, blankets, probes, and leak inspection
- Quarterly reservoir drain, water-circuit disinfection/rinsing, water-filter replacement, approved-water refill, condenser/grill cleaning, and water-flow-indicator cleaning
- Power-on self-test, indicators, operator controls, circulation through all three outlets, modes, probe response, alarms, flow, and pressure
- Water-temperature accuracy, HC/HS high-limit, snap-disc, LC/LS low-limit, and leakage-current testing
Required Tools and Equipment
- Current Blanketrol III Model 233 Operation and Technical Manual for the unit revision
- Gentherm TFRW 86171 Tri-matic temperature/flow/resistance tester with TM-4A probe extension cable (part 39005) and TM-6 hose assembly (part 91802)
- Calibrated 400 Series probe, mercury thermometer, or thermocouple as specified by the manual/Tri-matic instructions
- Calibrated leakage-current/electrical-safety analyzer
- Small slotted and Phillips screwdrivers, brush or vacuum, drain hose, and a sanitary drain/container of at least 3 gallons (11.4 L)
- Approved replacement water-filter assembly and approved Blanketrol hose/blanket for testing
- Sterile water or water passed through a filter ≤0.22 micron; do not use tap, distilled, or de-ionized water
- Current manual-approved disinfectant and concentration, pH or other suitable residual test strips, mild detergent, non-alcohol hospital-approved cleaner/disinfectant, PPE, and facility spill-control supplies
Step-by-Step PM Procedure
1. Remove the Unit From Clinical Use
Action: Confirm no patient is connected or relying on the system. Remove single-patient-use accessories, place the Model 233 in a controlled service area, set the switch to O, and disconnect mains power before inspection or internal access.
Expected outcome: The unit is identified, isolated, and safe for qualified PM work.
2. Verify Identity, Scope, and History
Action: Record asset tag, serial number, department, line rating, model, manual revision, operating hours/PM message, and due date. Confirm the equipment is Blanketrol III Model 233. Review prior PM, repairs, leaks, contamination, alarms, temperature complaints, and electrical-safety results.
Expected outcome: The correct procedure applies and unresolved history is identified before testing.
3. Inspect the Cabinet, Labels, Casters, and Storage Features
Action: Inspect the powder-coated cabinet, plastic top, membrane panel, displays, fill opening/strainer, drawer, bumpers, handle, grill, fasteners, two locking and two non-locking casters, and all identification/warning labels. Look for dents, cracks, missing parts, corrosion, residue, modification, or exposed components.
Expected outcome: The cabinet is complete and secure, casters roll/lock correctly, and all labels are present and legible.
4. Inspect the Power Cord and Plug
Action: Inspect the entire hospital-grade cord, strain relief, plug, prongs, cord holder, and equipotential/grounding features for cuts, exposed conductors, bent or missing prongs, looseness, heat damage, or contamination.
Expected outcome: The cord and grounding features are intact and safe.
5. Inspect Couplings, Hoses, Blankets, and Probe
Action: Inspect all three male outlet and three female return couplings for alignment, tightness, free collar movement, and leakage. Inspect approved connecting hoses, reusable blankets, couplings, and 400 Series probe/cable for cracks, punctures, kinks, stains, damaged insulation, leaks, or unauthorized accessories.
Expected outcome: Connections are straight, secure, and leak-free; accessories are compatible and serviceable.
6. Clean the Exterior and Accessories
Action: Clean the unit with water and mild detergent, then an approved non-alcohol topical cleaner/disinfectant. Wipe away residue with a damp cloth and dry. Clean reusable blankets and extension hoses only by their current instructions; do not autoclave or gas-sterilize them. Dispose of single-use blankets per policy.
Expected outcome: Surfaces are visibly clean, dry, undamaged, and free of chemical residue. Alcohol or strong undiluted disinfectants were not used.
7. Drain the Reservoir
Action: Route the manufacturer drain hose downward to a sanitary drain or container. Attach it to one male outlet, power the unit, select TEMP SET then MANUAL CONTROL, and allow pumping until LOW WATER stops operation; silence the alarm, switch off, unplug, and allow gravity drainage to finish. Repeat the outlet check as needed so circulation is verified through each of the three male couplings.
Expected outcome: The reservoir drains safely, LOW WATER protection operates, and all three outlet paths circulate without leakage or obstruction.
8. Disinfect and Rinse the Water Circuit
Action: Follow the current manual’s regional fluid-circuit disinfection procedure exactly. For the Revision I household-bleach procedure, use the listed 227 mL household bleach, fill with approved warm water, circulate in heating at 38 °C for 5 minutes after reaching temperature, drain, and perform three bleach-free rinse cycles. After the final refill/circulation, test for residual bleach and repeat rinsing if detected.
Expected outcome: The circuit is disinfected and no disinfectant residual remains. Chemical handling, concentration, contact conditions, disposal, and local policy are satisfied.
9. Replace the Water Filter
Action: With the unit drained and unplugged, qualified personnel extend the drawer and replace the T-shaped water-filter assembly. Install it with the cap/screen down and flow arrow pointing left, connect both hoses, tighten both clamps, and restore the drawer.
Expected outcome: A new approved filter is correctly oriented, secure, and leak-free.
10. Clean the Condenser, Grill, and Water-Flow Indicator
Action: Remove the front grill and brush or vacuum both sides and the condenser fins without bending them; reinstall the grill. Qualified personnel clean the water-flow indicator according to Section 5-12 if inspection or flow performance indicates service, preserving its O-ring and leak-tight hose connections.
Expected outcome: The air path is clear, fins are clean and straight, the grill is secure, and the flow indicator is clean, intact, and leak-free.
11. Refill With Approved Water and Leak Check
Action: Confirm the drain hose is removed. Add approximately 2 gallons (7.6 L) of sterile water or water filtered to ≤0.22 micron, stopping at the strainer. Do not overfill and do not use alcohol, tap, distilled, or de-ionized water. Connect an approved hose/blanket and inspect all serviced joints and couplings during circulation.
Expected outcome: Water is at the correct level, the circuit primes, and there is no internal or external leakage.
12. Perform Power-On and Indicator Tests
Action: Connect to a grounded hospital-grade outlet and switch to I. Verify the green switch light, processor self-test, and CHECK SETPT status. Hold TEST INDICATOR and verify the beep, button LEDs, low-water/power-failure LEDs, and all display segments illuminate.
Expected outcome: Startup, audible annunciation, indicators, and displays operate correctly without an unresolved fault.
13. Exercise Controls, Probe Response, and Operating Modes
Action: Using the Section 2-3.2 system-test routine and approved accessories, verify TEMP SET, C/F, arrows, MONITOR ONLY, MANUAL CONTROL, AUTO CONTROL, SILENCE ALARM, and applicable gradient/SMART controls. Confirm 4–42 °C manual set range, 30–40 °C automatic set range, proper CHECK PROBE/CHECK SETPT responses, pump/heat/cool response, water-flow indication, and normal cancellation/shutdown.
Expected outcome: Each control, display, mode, alarm, probe input, pump, heater, compressor, and flow indication responds as specified with no abnormal sound, odor, vibration, or leak.
14. Check Flow and Pressure
Action: Connect the calibrated TFRW 86171, TM-6 hose, and required accessories according to the tester instructions. Measure and record circulation flow and pressure under the specified configuration.
Expected outcome: Flow is greater than 0.60 GPM. Pressure is recorded and meets the current Tri-matic/manual criterion for the test setup.
15. Check Water-Temperature Accuracy
Action: Use the TFRW 86171 or the manual-approved calibrated reference at the specified 37 °C test condition. Allow the system and reference to stabilize, compare the water display to the reference, and record both readings and error.
Expected outcome: Water-temperature display accuracy is within ±0.5 °C at 37 °C, consistent with the Model 233 specification and current tester instructions.
16. Test Low-Temperature Protection
Action: Qualified personnel follow Section 4-7 exactly, with power removed before moving internal jumpers. Test LC and LS individually at JP4, monitor cooling, power off after each trip, remove the jumper, and let water rise above 4 °C before the next test.
Expected outcome: Both LC and LS shut the unit down at 2.0 °C ±2.0 °C and display LOW LIMIT REMOVE FROM SERVICE.
17. Test High-Temperature and Snap-Disc Protection
Action: Qualified personnel follow Section 4-8 exactly, with power removed before moving internal jumpers. Test HC and HS separately, allowing water to fall below 42 °C between tests. Then test the snap disc using the specified HC/JP2 configuration; after cooling below 42 °C, confirm reset and perform the documented alarm-reset sequence.
Expected outcome: HC and HS each shut down at 44.0 °C ±2.0 °C with HIGH LIMIT REMOVE FROM SERVICE. The snap disc shuts down at 46.0 °C ±2.0 °C, shows SNAP DISC REMOVE FROM SERVICE and EE02, then resets after cooling.
18. Perform Leakage-Current Tests
Action: Using a calibrated analyzer and the manual procedure, measure with unit power OFF and ON, normal and reversed polarity, and with the unit operating in both heating and cooling as listed on the maintenance checklist. Record each reading.
Expected outcome: Every leakage-current reading is less than 500 µA.
19. Reset the PM Counter
Action: After all maintenance passes, qualified personnel reset HOURS UNTIL SERVICE to 500 by simultaneously pressing SILENCE ALARM, Decrement, and Increment. Do not reset the counter for incomplete or failed work.
Expected outcome: The PM reminder is cleared and the counter reads 500 hours.
20. Restore, Recheck, and Document
Action: Remove all test jumpers and return them to JP5 storage, reinstall every panel/grill/fastener, verify water level, clean/dry the unit, and perform a final leak-free power-on and functional check. After any repair, complete the manual’s First Time Set-Up/System Test Routine before patient use. Document measurements, chemistry, filter, parts, repairs, and disposition.
Expected outcome: The Model 233 is complete, clean, correctly filled, electrically safe, alarm-protected, and either returned to service with traceable results or clearly removed from service.
Electrical Safety Testing
The Blanketrol III Model 233 is Class I, Type BF equipment. Its quarterly/500-hour checklist requires leakage-current measurements with power OFF and ON, normal and reversed polarity, and while heating and cooling. The manual limit is less than 500 µA under every listed condition.
Also perform any protective-earth/ground-bond or other tests required by the facility’s adopted electrical-safety standard and after relevant repair. Record the analyzer, calibration status, standard/mode, configuration, each result, applicable limit, and pass/fail disposition. The manufacturer’s 500 µA leakage limit remains controlling where it is more restrictive.
Pass / Fail Criteria
PM Pass Criteria
- Model identity, cabinet, labels, casters, controls, cord, grounding features, couplings, hoses, blankets, probe, and accessories pass inspection
- Reservoir/circuit is disinfected and rinsed, new filter is installed correctly, approved water is at the proper level, condenser/grill are clean, and no leak is present
- Startup, indicators, displays, controls, alarms, probe input, pump, heater, compressor, operating modes, and circulation through all three outlets pass
- Flow is greater than 0.60 GPM; pressure meets the applicable tester criterion
- Water-temperature display is within ±0.5 °C at 37 °C
- LC/LS trip at 2.0 °C ±2.0 °C; HC/HS at 44.0 °C ±2.0 °C; snap disc at 46.0 °C ±2.0 °C with the correct messages/reset behavior
- All leakage-current readings are below 500 µA and the PM counter is reset to 500 only after complete passing maintenance
Remove From Service Criteria
- Cracked casing/panel, exposed components, damaged cord/ground, missing safety label, unsafe caster, incompatible accessory, punctured blanket, damaged probe, or any water leak
- Contamination or chemical residual cannot be cleared; wrong water was used and corrective flushing is incomplete; filter, air path, or water path cannot be restored
- Failed startup, control, indicator, display, alarm, mode, pump, heat/cool, flow, pressure, or temperature-accuracy test
- Any LC, LS, HC, HS, or snap-disc trip is outside its stated range or does not produce the specified shutdown/message/reset behavior
- Any leakage-current reading is 500 µA or higher, any other required electrical-safety test fails, or post-repair system testing is incomplete
Copy/Paste CMMS Work Order Procedure
This procedure is limited to Blanketrol III Model 233. Internal jumper tests, water-circuit service, calibration, and repair must be performed by qualified medical-equipment service personnel using the current official manual. Never test with a patient connected. Stop immediately for any water leak, exposed component, electrical hazard, uncontrolled temperature, or failed safety shutdown.