Agilent Technologies SD-1 User Manual page 13

1
Introduction
Check Valves
Principle of Operation
The retracting piston creates a negative pressure in the piston chamber above
the inlet check valve. Mobile phase flows upward past the check ball into the
inlet check valve, then into the piston chamber.
As soon as the piston starts to move forward, gravity causes the ball in the
inlet check valve to seat, preventing mobile phase from flowing back out the
inlet check valve. At the same time, a positive pressure is created in the piston
chamber which dislodges the outlet check valve check ball. Mobile phase flows
upward through the outlet check valve while the piston is moving forward.
When the piston retracts again, gravity causes the ball in the outlet check
valve to seat, preventing mobile phase flowing back out the outlet check valve,
and the cycle is repeated.
During manufacture, each check valve is closely inspected and then individually assembled
N O T E
in a clean-room. Check valves should be kept clean and in good condition for reliable,
reproducible flow.
SD-1 Solvent Delivery - User Manual 13