Thermo Scientific EASY-nLC 1200 Troubleshooting And Maintenance Manual page 32

1
Introduction
Hardware Components
Check Valve Assemblies
10 EASY-nLC 1200 Troubleshooting & Maintenance Guide
IMPORTANT EASY-nLC 1200 flow sensors are compatible with EASY-nLC 1000.
EASY-nLC 1000 flow sensors are not compatible with EASY-nLC 1200.
Only flow sensors whose serial number is larger than 1528-XXXXX can be used on
EASY-nLC 1200 systems (software plausibility check).
The flow sensors determine the flow rate of solvents passing through the system by measuring
the heat transfer through the fused silica capillary. Outside the capillary, a heating resistor on a
thermally optimized membrane is maintained above ambient temperature. When liquid flows
through the capillary, the temperature distribution upstream and downstream of the heating
resistor is disturbed. The two temperature sensors measure this temperature asymmetry.
Because the temperature distribution depends on both the solvent flow rate and the solvent
mixture, you must recalibrate the flow sensors whenever the composition of solvents A or B is
changed. For example, if you use methanol instead of acetonitrile or change the acetonitrile
concentration for the solvent B mixture, run the script
CAUTION Solvent B acetonitrile concentration >95% can damage the instrument!
The EASY-nLC 1200 instrument uses two flow sensors with a maximum measuring
range of 4.5 µL/min.
When the corresponding high-pressure (6-port rotary) valves for pumps A or B are in
position 1–2, the check valves perform these functions:
• The solvent-side check valve prevents backflow into the associated solvent inlet line when
the associated pump is emptying solvent to the waste beaker.
• The waste-side check valve prevents backflow from the waste beaker when the associated
pump is filling and drawing solvent from the associated solvent bottle.
Figure 7. Check valve connections
From the solvent reservoir bottle
on the top of the instrument
"Flow Sensors"
Solvent-side
check valve
Connected to
port 2 of
valve A or B
Waste-side
check valve
Routed to the waste beaker
on page 52.
Thermo Scientific