The air inlet valve has a check valve which blocks vapours of the solution in a bottle, preventing the vapours from escaping into the lab. The safety air outlet filter regulates the pressure during helium sparging.

• Better composition stability of the mobile phases
• Less shift of retention times
• No bacterial contamination

The check valve regulates the pressure when the negative pressure reaches 0,1 bar. This small negative pressure prevents evaporation of the liquid (lower vapour pressure) and still guarantees the stability of the flow rate. A negative pressure which is too high can influence the aspiration of a constant flow.