High pulsation dampeners

This paper summarizes different methods of pulsation dampening in high pressure plants, and shows how to control and optimize the effectiveness of damping measures by numerical pulsation analysis. 

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. 

Figure F-30 is an example of a system requiring compression of the gas upstreeun of the turbine. Some manufacturers offer a precompression gas conditioning package, as well as pulsation dampeners and a high-efhcienQr vertical absolute separator downstream of the compressor. Some manufacturers also offer both analog and digital simulations to solve dampening and vibration difhculties.

Electrochemical detectors are more sensitive to flow pulsation than UV-detectors and usually an efficient pulse dampener is required to minimize the contribution to baseline noise at high sensitivity. 

The instruments for polymer HPLC except for the columns (Section 16.8.1) and for some detectors are in principle the same as for the HPLC of small molecules. Due to sensitivity of particular detectors to the pressure variations (Section 16.9.1) the pumping systems should be equipped with the efficient dampeners to suppress the rest pulsation of pressure and flow rate of mobile phase. In most methods of polymer HPLC, and especially in SEC, the retention volume of sample (fraction) is the parameter of the same importance as the sample concentration. The conventional volumeters— siphons, drop counters, heat pulse counters—do not exhibit necessary robustness and precision [270]. Therefore the timescale is utilized and the eluent flow rate has to be very constant even when rather viscous samples are introduced into column. The problems with the constant eluent flow rate may be caused by the poor resettability of some pumping systems. Therefore, it is advisable to carefully check the actual flow rate after each restarting of instrument and in the course of the long-time experiments. A continuous operation— 24h a day and 7 days a week—is advisable for the high-precision SEC measurements. THE or other eluent is continuously distilled and recycled. 

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