86 1100 Series Nano Pump Service Manual
2 Troubleshooting and Test Functions
Flow Sensor Accuracy Calibration
Description
The flow sensor accuracy calibration test is designed to calibrate the flow
accuracy and to compensate the electronic offset of the nano flow sensor. This
test should be done if high flow accuracy is needed at flow rates lower than
500 nl/min.
The calibration of the flow sensor is based in the linear relationship between
the flow rate and pressure drop in a capillary. The zero point is corrected and
calibration factors are evaluated.
Step 1 The test begins with the initialization of the pump. After initialization, the
EMPV is opening to release the pressure. No primary flow is delivered. After 2
minutes the flow sensor offset and pressure offset are measured.
Step 2 The primary flow is set to 500 µl/min for 1 minute and the pressure drop over
the inline filter is measured.
Step 3 The pump is operating in the flow control mode and is delivering 2 µl/min for
approximately 3 minutes. At the end of this step the pump is switched to
pressure control mode. The actual pressure is the initial pressure.
Step 4 The pump is delivering solvent for 3 minutes at a pressure equal to the initial
pressure divided by 2. At the end of this step the corresponding flow sensor
response is measured.
Step 5 The pump is delivering solvent for 3 minutes at a pressure equal to the initial
pressure divided by 4. At the end of this step the corresponding flow sensor
response is measured.
Step 6 The pump is delivering solvent for 2 minutes at a pressure equal to the initial
pressure divided by 10. At the end of this step the corresponding flow sensor
response is measured.
Step 7 The pump is delivering solvent for 2 minutes at a pressure equal to the initial
pressure divided by 20. At the end of this step the corresponding flow sensor
response is measured.
Step 8 The EMPV is opening to release the pressure. No primary flow is delivered.
After 2 minutes the flow sensor offset and pressure offset are measured.
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