Training Center
KP
Bicarb Mixing Ratio
Theory of Operation
RTD.TR62 05/14BG ©2014 B|Braun Medical Inc. Avitum Division
BICP
Training Center
Mixing Ratio Theory of Operation
The Dialog+® Hemodialysis System monitors the speed of the Bicarb and Acid
pumps together with their relationship to the Dialysate flow rate.
The speed of the pumps are increased or decreased based upon the
conductivity setting programmed into the machine.
RTD.TR62 05/14BG ©2014 B|Braun Medical Inc. Avitum Division
Training Center
During preparation or treatment, if either of the pumps’ speed is outside of the
working range to achieve conductivity, a mixing ratio error message will be
displayed.
Example:
14.3
3.5
Flow Rates
BICLF
ENDLF
300 - 800
45X
Solution
Working Range
Working Range
RTD.TR62 05/14BG ©2014 B|Braun Medical Inc. Avitum Division
Bicarb Conductivity
Range
Final Conductivity
Range
2.0 – 4.0 mS/cm
12.5 – 16.0 mS/cm
Training Center
The working range values for mixing ratio are set during the installation
of the machine in Calibration 2.10 and may be adjusted for the
customer’s brand of concentrates.
Set Working
Value Range
RTD.TR62 05/14BG ©2014 B|Braun Medical Inc. Avitum Division
Training Center
Ratio Working Range
Monitor the mixing ratio using the overview screen
Monitoring the speed of the
Bicarb pump is an important part
of troubleshooting a Bicarb mixing
ratio alarm.
RTD.TR62 05/14BG ©2014 B|Braun Medical Inc. Avitum Division
Training Center
Mixing Ratio Relationship to Pump Speed
The speed of the pump can vary depending on the calibrated stroke value, the
prescribed Bicarb conductivity and flow rates.
18
Bicarb Mixing
Ratio
+/- 7
Alarm
25
Set Value
Alarm
32
Working range
RTD.TR62 05/14BG ©2014 B|Braun Medical Inc. Avitum Division
Training Center
Calculating the Bicarb Mixing Ratio
Dialysate Flow
ml/min
Bicarb Mixing Ratio =
=
Bicarb Delivery
ml/min
Bicarb Delivery
ml/min
Bicarb Delivery =
ml/min
Bicarb Delivery
=
ml/min
Stroke
Value
x
.226 ml
Bicarb
Pump
Speed
600 ml/min
Mixing Ratio =
28.25 ml/min
Mixing Ratio = 21.23
x 125 rpm
28.25 ml/min
RTD.TR62 05/14BG ©2014 B|Braun Medical Inc. Avitum Division
In this equation, the Dialysate
flow rate and stroke value
highlighted in yellow are
constant.
Training Center
Bicarb Mixing Ratio Alarms
Actions:
Observe the BIC-RATIO and BICP
pump speed and BICLF values using
the overview screen
Observation Example
Set value 3.5
142
142
17.98
17.98
RTD.TR62 05/14BG ©2014 B|Braun Medical Inc. Avitum Division
A mixing ratio of ≥ 18 and a higher than
expected BICP rpm is an indication the
Bicarb pump is running faster to achieve
the level of Bicarb required for the
prescribed conductivity level.
Training Center
KP
Bicarb Mixing Ratio Alarms
Possible Causes
RTD.TR63 05/14BG ©2014 B|Braun Medical Inc. Avitum Division
BICP
Training Center
Bicarb Mixing Ratio Alarms
Possible causes:
1. Solcart cartridge placement
2. Cartridge Holder O-Rings
3. Central Bicarb Suction Coupling integrity
4. Bicarb wand and PE tube integrity
5. Air in machine
6. TSBIC
7. BICLF
8. BICP
9. BICPOS
10. Faulty Power Board Motor
11. Faulty Digital Board
12. Faulty Analog Board
For additional information review troubleshooting modules
RTD.TR63 05/14BG ©2014 B|Braun Medical Inc. Avitum Division
Training Center
Bicarb Mixing Ratio Alarms
Possible Causes
Air in Machine
TSBIC
1- 4
5
6
BICLF
BICP
Electronic Circuits
7
8-9
10-12
Basic Checks and
Actions
RTD.TR63 05/14BG ©2014 B|Braun Medical Inc. Avitum Division
Training Center
KP
Bicarb Mixing Ratio Alarms
Basic Checks and Actions
RTD.TR64 05/14BG ©2014 B|Braun Medical Inc. Avitum Division
BICP
Training Center
Basic Checks and Actions
Possible causes with a low mixing ration value and higher
then expected BICP value.
Observation Example
Set value 3.5
►
Solcart cartridge placement
►
Cartridge Holder O-Rings
►
Central Bicarb Suction Coupling integrity
►
Bicarb wand and PE tube integrity
142
142
17.98
17.98
Actual values may vary
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Training Center
Basic Checks and Actions
Actions:
► Reposition the Solcart Cartridge
► Replace cartridge holder o-rings
off line. Disinfect the machine
after replacement.
RTD.TR64 05/14BG ©2014 B|Braun Medical Inc. Avitum Division
Training Center
Basic Checks and Actions
Actions:
► Check for the presence of air in blue
tubing when the BICP pump is on and
the coupling connected to the central
wall connector. Check Central Bicarb
Suction Coupling connector and O-ring
for integrity. Clean or replace the
connector or o-ring if necessary
►
Check for air in the Bicarb concentrate
tubing. Check Bicarb wand and PE
tube for integrity
RTD.TR64 05/14BG ©2014 B|Braun Medical Inc. Avitum Division
Check for residual Bicarb
Check for cracks in tubing
and connector
Training Center
KP
Bicarb Mixing Ratio Alarms
Air in Machine
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BICP
Training Center
Bicarb Mixing Ratio Alarms caused by air in machine
Actions:
► Check for the presence of air in the tubing at the marked points. If air is
present troubleshoot independently utilizing Air in Machine Module.
Air at this point suggests a fault in
the Water Sub-Rack
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Air at this point suggests a fault in
the DF Sub-Rack
Training Center
KP
Bicarb Mixing Ratio Alarms
TSBIC Check
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BICP
Training Center
Relationship of Temperature and Conductivity
Conductivity is a measurement of the movement of free electrons in a conductor.
When measuring Dialysate, electrons move easier when the temperature
increases resulting in a higher conductivity reading without changing the content
of the mixture.
A temperature deviation at TSBIC of 1°C
can equate to ≈0.3 mS/cm difference at BICLF
A faulty or mis-calibrated TSBIC can cause
deviations in the BICLF reading thereby causing
Bicarb Mixing Ratio alarms.
RTD.TR66 05/14BG ©2014 B|Braun Medical Inc. Avitum Division
Training Center
Bicarb Mixing Ratio Alarms caused by TSBIC
Actions:
► Check the accuracy of TSBIC with a calibrated
external meter in TSM Test 1.11
If TSBIC checks within specifications proceed to additional troubleshooting modules
► If necessary, calibrate using the instructions in the
Service Manual. (tolerance +/- .5°C )
Values for pumps and heater are for reference only. Actual values may vary.
RTD.TR66 05/14BG ©2014 B|Braun Medical Inc. Avitum Division
Training Center
KP
Bicarb Mixing Ratio Alarms
BICLF Check
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BICP
Training Center
Bicarb Mixing Ratio Alarms caused by BICLF
Actions:
► Check the accuracy of BICLF with a calibrated
external meter in TSM Test 1.12 using diluted
concentrate solution as per service manual
If BICLF checks within specifications proceed to additional troubleshooting modules
► Calibrate according to the instructions in the Service
Manual only if necessary. (tolerance +/- .2mS/cm )
Values for pumps and heater are for reference only. Actual values may differ.
RTD.TR67 05/14BG ©2014 B|Braun Medical Inc. Avitum Division
Training Center
KP
Bicarb Mixing Ratio Alarms
Bicarb Pump
RTD.TR68 05/14BG ©2014 B|Braun Medical Inc. Avitum Division
BICP
Training Center
Bicarb Mixing Ratio Alarms caused by the Bicarb Pump components
Actions:
► Check for the BICP_S signal using the overview screen.
► The BICP_S signal must be within 10 rpm to the BICP SIGNAL
142
6
17.98
17.98
Possible causes of failure:
► Stuck pump
► Faulty Hall Sensor BICPPOS
► Faulty wire connections
► Faulty Power Board Motors
► Faulty Digital Board
The values shown are samples
only. Actual values may vary.
RTD.TR68 05/14BG ©2014 B|Braun Medical Inc. Avitum Division
BICPPOS
Training Center
Bicarb Pump Breakdown
1. Motor
Speed controlled by the LLC to run at a
speed that will deliver the required solution
amount to the BICLF conductivity sensor
1
2. Bell-housing
5
Contains the magnets that trigger the
BICPOS sensor #4
3. Pump Body
4
2
Pumps Bicarb from supply into machine
4. Supervisor sensor BICPOS
Monitors the speed of the pump
sends signal to the LLS
5. Assembly Jig
Used during the pump assembly ensuring
proper placement between the motor-head
and bell-housing
RTD.TR68 05/14BG ©2014 B|Braun Medical Inc. Avitum Division
3
Training Center
Bicarb Mixing Ratio Alarms
The Bicarb Pump Body may be worn causing the flow of Bicarb to the
BICLF(Bicarb conductivity cell) to be intermittent.
TESTS:
Check the pump delivery using Test 1.12 by looking for
fluctuations of the conductivity value at BICLF
Explanation:
1
If BICLF 1 continuously fluctuates
with a constant speed at the
Bicarb pump 2 and FPE 3 the
Bicarb pump body may be worn
3
2
Corrective Actions:
► Replace the Piston Pump and calibrate using Calibration
2.8 and in accordance with the Service Manual
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Training Center
KP
Bicarb Mixing Ratio Alarms
Electrical Connections
RTD.TR69 05/14BG ©2014 B|Braun Medical Inc. Avitum Division
BICP
Training Center
Block Diagram of circuits associated with Bicarb Mixing Ratio Alarms
►
Review basic modules before considering electronic components
RTD.TR69 05/14BG ©2014 B|Braun Medical Inc. Avitum Division
Training Center
Check Basic Board Connections for the appropriate
circuits that may be faulty
► Disconnect and reconnect ribbons and harnesses
1 BICLF
1.
2 BICP
2.
2
3 TSBIC
3.
6
4.
4 Power Board Motors
4
5 Digital Board
5.
6 Power Supply Hall Sensors
6.
5
6
3
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1
Training Center
KP
Bicarb Mixing Ratio Alarms
BICP Low RPM
RTD.TR70 05/14BG ©2014 B|Braun Medical Inc. Avitum Division
BICP
Training Center
Bicarb Mixing Ratio Alarms
Possible causes with a High mixing ration value and lower
than expected BICP rpm.
Observation Example
Set value 3.5
►
65
65
►
33.10
33.10
►
►
►
Incorrect concentrate
TSBIC deviates from actual value
BICLF deviates from actual value
Worn Piston Pump
Faulty DBK
The values shown are samples only.
Actual values may vary
RTD.TR70 05/14BG ©2014 B|Braun Medical Inc. Avitum Division
Training Center
Corrective Actions and Checks
Incorrect concentrate mixture
► Check Bicarb concentrate solution for proper mixture. Improperly
mixed solution may be too concentrated causing the machine to run
the BICP pump at a slower rpm to achieve the desired amount of
conductivity.
TSBIC deviates from actual value
► Check TSBIC temperature using Test 1.11 (see TSBIC Module)
BICLF deviates from actual value
► Check BICLF conductivity using Test 1.12 (see BICLF Module)
RTD.TR70 05/14BG ©2014 B|Braun Medical Inc. Avitum Division
Training Center
Corrective Actions and Checks
Worn Piston Pump
The piston pump can wear over time allowing solution from a high pressure
central supply to leak through the pump causing the BICLF conductivity
sensor to react by slowing down the BICP pump thereby causing a Bicarb
mixing ratio alarm.
►
►
►
Calibrate Bicarb pump BICP using Calibration 2.8
Check the stroke value after the calibration (range 199-245 ul/head rot.)
Replace BICP pump body if the stroke value is out of range (follow the repair matrix)
Concentrate Supply
0-1bar
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Training Center
Corrective Actions and Checks
DBK Spring ( Solcart B ® option only)
The DBK spring could be weak allowing Bicarb to seep into the degassed
and heated side of the upline tank causing the fresh water being pulled into
the DF block to be slightly conductive. The BICLF conductivity sensor will
react by slowing down the BICP pump thereby causing a mixing ratio alarm.
RTD.TR70 05/14BG ©2014 B|Braun Medical Inc. Avitum Division
Training Center
Corrective Actions and Checks
1. Connect a calibrated conductivity
meter to the input of the DF block and
measure the conductivity.
2. The reading on the meter should be
0.00 mS/cm or the value of the RO
water source.
3. Replace the DBK spring if a
conductivity level is greater than the
value of the RO water source.
RTD.TR70 05/14BG ©2014 B|Braun Medical Inc. Avitum Division