Flow control pulsation dampeners

In all cases, to achieve a proper regulation of the flow, a pulsation damper is used. It operates on the principle of a mechanical ballast or can be electronically controlled. The simplest mechanical ballasting device is a coil with a low cross-section, several metres in length, placed between the pump and the injector. Under the influence of a wave of solvent, the tube uncoils slightly which increases its internal volume and dampens the variation in pressure. 

The GDV discussion is a particularly difficult one for pumps still having membrane-based pulsation dampeners. In this case, the GDV also depends on the system pressure, and by that on the separation flow rate [77]. While all major manufacturers of modern UHPLC pumps nowadays have established electronic control mechanisms in their high-end and most middle-class instruments that allow a virtually ripple-free flow delivery without dampeners, some older pumps or simpler entry-level models still have to rely on mechanical dampening. It would not be appropriate in general to use such pump types together with MS detection. 

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