Agilent InfinityLab LC Series Vialsamplers User Manual 25
1Introduction
Operating Principle
Analytical Head
The analytical head is driven by the stepper motor that is connected to the drive
shaft by a toothed belt. The drive nut on the spindle converts the circular
movement of the spindle to linear motion. The drive nut pushes the sapphire
piston against the tension of the spring into the analytical head. The base of the
piston sits on the large bearing of the drive nut, which ensures the piston is
always centered. A ceramic ring guides the movement of the piston in the
analytical head. The home position of the piston is sensed by an optical sensor
on the hydraulic unit board while the sample volume is determined by counting
the number of steps from the home position. The backward movement of the
piston (driven by the spring) draws sample from the vial.
Injection Valve
The two-position 6-port injection valve is driven by a stepper motor. Only five of
the six ports are used (port 3 is not used). A lever/slider mechanism transfers the
movement of the stepper motor to the injection valve. Two microswitches
monitor switching of the valve (bypass and mainpass (main path) end positions).
No valve adjustments are required after replacing internal components.