1220 Infinity II LC System User Manual 145
Test Functions and Calibration
9
Solvent Delivery System
Solvent Delivery System
Pump Leak Test Description
The leak test is a built-in troubleshooting test designed to verify the tightness
of pump components. The test should be used when problems with the pump
are suspected. The test involves monitoring the pressure increase at very low
flow rates while different plungers are delivering solvent. At these very low
flow rates, very small leaks can be detected by evaluating the pressure profile
as the pump runs through a predefined pumping sequence. The test requires
blocking the pump with a blank nut, then running the test with isopropanol
(IPA), while monitoring the pressure profile.
Ramp 1
After initialization, plunger 2 is at the top of its stroke. The test begins with
plunger 1 delivering with a stroke length of 100 μL and a flow of 153 μL/min.
The plunger sequence during the pressure ramp is 1-2-1-2. The pressure
increase during this phase should be linear. Pressure disturbances during this
phase indicate larger leaks or defective pump components.
Plateau 1
Plunger 2 continues to pump with a flow rate of 2 μL/min for approximately
one minute. The pressure during the plateau should remain constant or
increase slightly. A falling pressure indicates a leak of >2 μL/min.
Ramp 2
The flow is changed to 153 μL/min, and plunger 2 continues to deliver for the
rest of its stroke. Then plunger 1 continues to pump to complete the second
half of the ramp.
Make absolutely sure that all parts of the flow path that are included in the test are very
thoroughly flushed with IPA before starting to pressurize the system! Any trace of other
solvents or the smallest air bubble inside the flow path will definitely cause the test to fail!
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