Healthy Lifestyle & Kidney Health

Chronological Machine Test Sequence — The Complete Roadmap

This comprehensive roadmap charts every phase of the B. Braun Dialog+ automated system verification sequence.

Tracing the machine's path from the moment the physical power switch is thrown until the safe operational loop allows a patient connection.

POST Fluid & Heat SAD/BLD DFS Pressure HDF Online Ready

1. Power-On Self-Test (POST)

30-60 Seconds

Top-Screen Message

Phase 1

"System Booting..." or "Self-Test Ongoing"

What is happening: The machine verifies its basic core electronics before initiating water or fluid contact. The Low Level Supervisor (LLS) runs internal checks on the ROM/RAM registers, verifies safety relay switching paths, sounds the backup buzzer, and tests the watchdog timers.

LLC/LLS Focus: LLS Codes 16001 - 16028 (Watchdog & Buzzer check), Code 1155 (+/- 12V balance check)

Possible Failures: Frozen screen, continuous tone buzzer, or a failure to boot into the main operating system.

Biomed Action: Check power supply voltages, ribbon connectors to the front panel display board, or swap out a degraded main processor card.

2. Fluid Level Regulation & Thermal Ramp-Up

5-7 Minutes

Top-Screen Message

Phase 2

"Preparation Mode" / "Water Inlet" / "Heating"

What is happening: The machine draws raw water through the entry port to fill the internal hydraulic tracks, generates a vacuum loop using the degassing system to remove dissolved micro-bubbles, and triggers the heating element to raise the temperature to a standard 37°C.

LLC/LLS Focus: LLS Codes 22000 - 22012 (Temperature tracking loop)

Possible Failures: Alarm "Water Supply Disturbed" or persistent cold loop errors.

Biomed Action: Verify water room supply pressure is adequate. Enter TSM test 1.9 to check and calibrate the DMV (water inlet pressure reducer valve) offset. Check fuses F5/F6 or look for heavy calcification on the 30-Ohm heating element rod.

3. Safety Sensor Calibration (SAD & BLD)

30-45 Seconds

Top-Screen Message

Phase 3

"SAD Functional Test" or "BLD Optical Test"

What is happening: The machine tests the protective barriers touching the extracorporeal line paths. The Sensor Air Detector (SAD) sweeps its ultrasonic arrays to check empty-tube versus full-tube values. Concurrently, the Blood Leak Detector (BLD) projects red and green wavelengths through its glass sleeve to calibrate base voltage targets.

LLC/LLS Focus: LLC/LLS Codes 11xxx family (Blood Leak)

Possible Failures: Sensor calibration failures, false bubble faults, or ambient light interference.

Biomed Action: Check that the blood lines are seated firmly at the absolute back of the air detector block. Clean the glass tube inside the BLD to remove any residual scale build-up, and recalibrate baseline sensor voltages via TSM test 1.7.

4. Volumetric Dialysate Flow System (DFS) Pressure Tests

3-5 Minutes

Top-Screen Message

Phase 4

"DFS Self-Test Ongoing" or "Balance Chamber Test"

What is happening: This is the most complex automated phase, consisting of 12 distinct internal steps checking the structural integrity of the balance chambers, membranes, and tracking valves via pressure shifts.

LLC/LLS Focus: LLC 1220x to 1275x series / LLS 12019 to 12183

Possible Failures: Pressure decay, valve leakage, or torn membranes.

Detailed Breakdown of the 12 Fluid Phases:

Phases 1-2: Pressure Build-up — The machine pressurizes the balancing circuit up past 425 mmHg. Failing indicates a severely torn chamber membrane or weak FPE (inflow) pump.

Phases 3-4: Pressure Drawdown & Valve Isolation — The UF pump runs backwards to lower circuit pressure below 380 mmHg. It checks if the VBP or VDE valves leak. Failure often points to a kinked external drain hose or failing UF reed sensors.

Phase 5: VDA Valve Test — Tests structural backpressure integrity across air separation lines.

Phases 6-8: Membrane Creep Check — Tests structural balance chamber diaphragms under localized static holds. Pressure drift indicates an internal membrane puncture.

Phases 9-12: Entry Assembly Check — Isolates entry balance arrays (VEBK/VDEBK valves) to guarantee zero backward cross-contamination between clean and spent fluid lines.

Biomed Action: Rebuild valve blocks with clean membranes or replace matching balance chamber diaphragms in pairs to ensure even volumetric displacement.

5. HDF-Online Verification Loop (If Configured)

1-2 Minutes

Top-Screen Message

Phase 5

"HDF Validation Ongoing" or "Sub. Leakage Test"

What is happening: If the clinical staff selected Hemodiafiltration (HDF) mode, the machine initializes its secondary substitution pump loop. It runs high-pressure hold sequences to test the integrity of the internal Diacap Ultra filters and check valves.

LLC/LLS Focus: LLS Codes 15120 (Filter block) & 40000 - 40019 (Substitution path leakage loop)

Possible Failures: High fluid resistance errors or structural leakage across substitution line couplers.

Biomed Action: Replace the clogged online pyrogen filters. Check structural alignment across the DDE and RVDA safety check-valves.

6. Ready State / Standby Mode

Instantaneous

Top-Screen Message

Phase 6

"Ready for Dialysis" or "Standby Active"

What is happening: All sequential LLC/LLS handshakes have successfully closed with passing values. The fluid system drops into an optimized bypass loop to conserve concentrates, the screen background turns green, and the blood pump motor activates its interface queue, waiting for the lines to be connected to the patient.

LLC/LLS Focus: All handshakes complete — system ready for therapy.

Clinical Action: Machine is now ready for patient connection. Proceed with dialyzer priming and patient hook-up.

🎯 Master Troubleshooting Tip for Educators

Critical

Isolate the Failure by Progress Bar Position

When training new staff, point out that if a machine stalls during preparation, they must look at the exact progress bar position on the screen.

10–15%
Phase 2 Failure

The machine is failing its initial water heating/degassing stage.

Check water supply, heating rod, degassing pump.

Near 100%
Phase 4 Failure

The machine is failing the balance chamber pressure tests.

Check balance chamber membranes, valves, and O-rings.

Isolating the timing of the failure tells you exactly which subsystem is acting up.

Training Pearl:

Teach staff to never restart the machine immediately on a stall. The progress bar position is a vital diagnostic clue that is lost on restart. Always document the percentage where it stopped.