Pump pulsation dampener

Especially on the discharge side of pumps pulsation dampeners are very expensive. For that reason the attempt to manage pulsation without dampeners is often made. That is sometimes possible, if other kinds of dampening mechanisms can be used. 

A poorly designed discharge manifold can cause shock waves and excessive pressure peaks. This manifold should be as short and direct as possible, avoiding any sharps turns. The conventional small atmospheric air chamber, often furnished with pumps, supplies only a moderate cushioning effect. For best results, this air chamber should be supplemented by a large atmospheric air chamber or by a precharged pulsation dampener. 

Pump pulsations. 6. Incorporate pulse dampener into system. 

Use centrifugal pumps. If positive displacement pumps must be used, these pumps must be fitted with approved pulsation dampening equipment surge tanks may also be required, particularly for very short and very long pipe runs. 

Vetter, G., Seidl, B. Pressure Pulsation Dampening Methods for Reciprocating Pumps. Proc. 10th Int Pump Users Symp., Houston TX, USA 1993, 25-39. 

To further minimize possible pressure pulsation, the pumps can be installed together with a pulsation dampener mounted at the discharge. Pulsation dampeners are air pressurized or spring loaded to ensure a smoother product flow in the process line. Slow rotational speed of the pump s crankshaft also helps to minimize pressure pulsation. 

The flow of the SCF under pressure is maintained by long-stroke piston pumps, reciprocating piston pumps, or membrane pumps which deliver the mobile phase in liquefied form. The fluid is then heated to supercritical conditions before entering the column. Pressure and flow rate must be kept as constant as possible in order to maintain constant conditions for separation and to achieve a stable baseline in the chromatogram. Oscillating pumps can therefore have three heads, which deliver at different times, or a pulsation dampener in order to minimize pulsation. 

Gear pumps Higher the viscosity, the lower the rated rpm. On the discharge install a check valve and an expansion chamber or pulsation dampener, the latter to reduce noise. For infrequent operation, operating pressure should be 20-30%... 

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 9.14 Pulsation reduction (a) simplex pump, (b) pulsation dampener, (c) triplex pump.

Diaphragm, piston, and peristaltic pumps all deliver liquids in pulses. This uneven delivery can cause dosing problems when mixing is not sufflcient to ensure a rapid distribution of the chemical into the process water stream. Devices and systems are available to help smooth the delivery from these types of pumps. These devices are sometimes called pulsation dampeners (Figure 7-6). There are several designs. 

Figure 7-6 Chemical metering pump installation with pulsation dampener...

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