Part Nbrs. WaG/HO
Pressure, which transfers through a typical liquid at 1440 meters per second, or 5200 Kilometers per hour, well over 3,000 mph bounces back form changes in cross sectional area. A concentric reducer for example is seen by a pressure wave as a "brick wall", the reflection simply produces an additional frequency.
As our objective is to address pressure changes, we must first make them enter the damper. The smaller the hole through which they enter, relative to the size of the chamber into which they enter, the more efficiently they are dissipated.
The essential design parameter is therefore to go from a large pipe to a small hole without bouncing the pressure wave back up the system, (though there is some reflection from the open orifice end). This is achieved with a taper of include angle not wider than 7 degrees. This angle is as effective in not reflecting the pressure waves as a 5D bend. We now have the small orifice.
The pulses and shocks have been intensified, and are EXPLODED into the damping chamber, and the mass transfer has had a local velocity increase with minimal increase in backpressure.
Pressure pulse transients die away by a cube law of distance from orifice to chamber wall, & the compressibility of the huge volume within the large diameter, smooths the flow fluctuations. These would otherwise result in low frequency acceleration head pulsation from system resistance to flow.
Be careful of plain "tanks" with a smaller entrance than the pipeline size. Such tanks simply produce higher frequencies in your system and force your piping to do the damping.
The "e" number in the selection tables is the equivalent volume in3 of gas loaded damper. For example a damper with a volume of 50 liters may have an "e" of 25 in3, or be the equivalent of a 0.4 Liter gas loaded damper to give only a 10% acceleration head pulsation.
WaveGuards are not "black box witchcraft", the ratio of inlet size to chamber diameter gives the "discharge coefficient" and orifice selection is by the Helmholtz calculations.
To apply efficient no moving parts dampers, you need to be able to tolerant a typical 2 bar pressure drop, have lots of space, and large check book.