4 通采样和切换阀

Sampling valve basically supports the discrete volumes of the treated samples stream to periodically inject into the carrier gas stream of the chromatograph. Sampling valves are fitted with electric or pneumatic actuators which help them to be operated automatically. Switching valve are critical if binary pumps are used. It allows employment of different desired mobile phases. Switching valve consists of five parts: control unit, connecting device, valve body, a rotor and preloaded assembly.

Isolate a column to prevent a compound, emerging from an upstream column, from being irreversibly adsorbed. In the figure, CO₂ is separated from air in Column 1, and bypasses Column 2 when the valve is switched to position B. After the CO₂ is detected, the valve is switched back to position A and O₂, N₂, CH₄, and CO elute from Column 2 to the detector.

Sampling valve may be used to connect the LC and GC instruments to allow fast and dependable introduction of large sample volumes onto a capillary GC column.

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