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Explanations A through F

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The purpose of the analogies is not absolute definition; it is to assist in visualizing the different phenomena.

A. Shake a pipe, generate a pressure pulse.
B. Turn a pulse instead of reflecting it.
C. Dissipate a transient, why increase the frequency.
D. Importance of smaller pipes.
E. Changes in diameter - Orifices, Eccentric and "Conc" reducers, the 7 Degree taper.
F. Is it an Accumulator, Orifice Reactive Resonator, or a true Pulsation Dampener?

 
A. Shake a pipe, generate a pressure pulse.

Leave the end of the garden hose attached to a closed "tap" or faucet. Extend the hose uphill, and leave open but full of water. Hold the middle of the hose, then jerk it. Water spurts out. The jerk created pressure, if not, nothing would have come out. Similarly, shaking a pipe causes pressure pulsation in the liquid.
Hose
When the engine or motor attached to a pump, is not perfectly installed, the pipe attached to the pump will vibrate. This can be measured as liquid pressure pulsation. It will be significant when the shaking is along the axis of the pipe. There is no difference between pushing liquid in a pipe, and pulling a pipe along a column of liquid, in terms of liquid pressure.

 

B. Turn a pulse instead of reflecting it.

Good Bend
Reflection makes yet another frequency

LR "L"Whereas a long radius 90 will be better in terms of volume / mass flow, a pressure wave traveling over 5,000 kilometers per hour, will see it as a "brick wall", - just as it does with a "hard 90".
A 22.5 Degree + 22.5 Degree
Worst Bend
There are different stiffnesses for each of these direction change methods.
These stiffnesses impact the pipe mechanical vibration frequencies.
 


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C. Dissipate a transient, why increase the frequency.

TransientsWhere Diameter of a vessel is 8 times the Diameter of a pipe, high frequency pressure pulse transients will have died away before they can bounce off the nearest point of reflection and find their way out into the rest of the system.
This is "good" to the extent that it is not increasing the load on the pump by imposing an orifice against pump delivery.
"High frequency transients" High Frequency Transient Wave
Liquid chambers alone will cost too much and be hugePulse Volume
The problem is that the pulse may have a substantial volume as well as pressure amplitude. When the duration of a pulse is sustained for a measurable length of time, the pulse will have volume; it will not simply be a transient. The volume of the dampener vessel required to provide sufficient liquid compressibility will be between 10,000 & 100,000 times the volume of the pulse, depending on the pulse characteristics.

 
D. Importance of smaller pipes.
No Orifice1. As high frequencies die away relative to the ratio of diameters, your dampeners will be smaller and more efficient when you keep your pipe sizes down.
2. Even more important is that the smaller the pipe, the more dissipative it is, so the pipe will scrub out some pulsation.
3. Additionally, a dissipative pipe system will not become a pulse amplifier.
Unfortunately you can not just step the pipe diameter down, the step will return the pulse.
 

E. Changes in diameter - Orifices, Eccentric and "Conc" reducers, the 7 Degree taper.
A pressure occurrence travels at Mach 5 and sees any reduction in cross sectional area that is steeper than an included angle of 7 degrees as a “brick wall”.

Sharp Angle 7 Degrees
Nearly all of a pressure spike can be caused to go into a dampener from a large diameter pipe by compressing it down a 7 degree taper. pulse reflection

 
F. Is it an Accumulator, Orifice Reactive Resonator, or a true Pulsation Dampener.
An orifice makes it harder for the pump. It reflects the pulsation, but helps to protect the pipe system.Reactive Type

A gas bag makes the system soft, which is good for the pump. The residual pressure pulses go past, no good for the pipe.

ByPass

True DamperA true dampener helps the pump and protects the system.

In essence a dampener is large diameter, multi ported, and has elasticity. An orifice resonator is bad for a pump. Soft accumulators do not protect pipes.

Pulsation Dampeners - PulseGuard Inc.

 

 

When the bend is gradual enough, a pressure wave can be carried round a corner without reflection. radius of bend “scarf joint” a.k.a. “fabricated 45” reflects some and transmits some of a pressure wave. Worst “hard 90” Typical for vane and centrifugal pumps Reducer is fine for flow but not for acoustics pulse reflection 7 degree is good for acoustics and for flow And makes it harder for the pump to pump. The pulse will by-pass a volume accumulator. True pulsation dampener with nitrogen compressibility for acoustic and volumetric protects pump and pipes. pressure
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