Liquid Dynamics International Ltd. - Piping System Analysis / Piping System Simulation


Pipeline and Pump User Problem
Analysis, Diagnostics and Prediction by Software

Exposing the mysteries - removing the "witchcraft from pulsation, shock and piping analysis, by graphics & "cartoons" for problem description and understanding answers.

P. 2 A. Shaking a pipe generates pressure pulses.
B. How to turn pressure waves instead of reflecting them.
C. Transient dissipation.
P. 3 C. Transient dissipation cont’d. Acoustic volumes.
D. Reduce pipe sizes.
E. Diameter changes are points of reflection.
F. Be careful of orifices.
P. 4 Pressure velocity – 3600 mph, goes a mile in a second. Mass flow only 15 mph. How resonant pressure amplification can occur.
P. 5 The vital importance of large diameter. Why pressure changes must pass into flow – not go past any attenuator.
P. 6 Pumps, with one exception, are not the cause of shock, surge, or pulsation pressures. Hard arteries and pipes kill people and pumps.
P. 7 Gauges are “pressure indicators” that is why the symbol is PI. They can only indicate dynamic activity; gauges can not measure it.
P. 8 Suction supply line problems. When starting flow in a pipe to a pump, and repetitively in the case of a reciprocating machine.
P. 9 Preventing supply piping from destroying a pump. Two do’s two don’ts. Decoupling system response from negative spike excitation.
P. 10 “Controllers”, back pressure valves, relief valves, and check valves, all disrupt mass flow and so the pressure equilibrium.
P. 11 Synopsis, overview. Flow is like the tide, it rises and falls. Pressure is like the waves, they do the damage by repeatedly hammering.

Graphics, interpreting pressure over time oscillograph traces, to identify the sources of shock and pulsation. Knowing what is normal. Setting the system stability needs.

P. 14 1. Suction starvation time lag.
2. Foot valve oscillation.
3. Typical acoustic response, tells nothing more than the length of the supply pipe.
P. 15 cont’d.
4. Channel “cavitation” from high velocity and 4:1 Delta P.
5. Vortex frequencies – meter disturbance inaccuracy.
6. Normal pump start-up.
P. 16 Ultra stable circuits with gear pumps. Typical packed plunger systems. Acceptable stabilities by various components and design purpose.
P. 17 Dosing and mixing system fluctuations. The horror of compressible liquids, high pressure, and pipe response to low volumetric efficiency.
P. 18 Triplex reciprocating plunger pump – analysis of motion, valve action, mass oscillation, velocity jump, membrane response and all.
P. 19 Centrifugal system start-up surge wave, backflow bang, valve deceleration hammer. A typical “power” pump / API 674 system design.

Measurement, recording, real time large fast hard copy validation, data capture of pressure signals. Pipe system surveys, and preparation for analysis and diagnosis.

P. 22 On site services: PulseDoctor, ShockDoctor, PipeDoctor.
P. 23 Characteristics of equipment used. WitchDoctor and Which Analyst.

Modeling pipe systems before fabricating miles of metal saves finding problems that could have been
easily avoided, with a few runs of ShockView and PulseView.

P. 26 Prediction by ShockView software. The model schematic
P. 27 Plots
A. Potential danger
B. Pressure drop.
C. Lack of dissipation.
P. 28 First consider A, B, C input data necessary for shock remodeling
P. 29 PulseView models relationship between 33 system parameters
P. 30 7 explanations of oscillographic plots and findings
P. 31 15 system parameters necessary plus pump parameters for a full model.
P. 32 Outline of possible equations and sources.

Pipe system design detail, that can prevent instability, reduce equipment installation time and cost, whilst easing service and reducing "down time".

P. 33 A view of 30 OctoPussy systems that prevented interaction between pumps and valves “talking” to each other.
P. 34 The principle is simple, see it at work every day under your hood. Example, the thought process behind their design. Uses of piping base “pass through” interception with a single pump to pipe system. For two pump systems.
P. 35 Turbocharge your pump with what it needs – Volume – not force. Components that make anybody’s damper worth using. Saving height to improve relative head is counter-productive; the tight bends necessitated lose more than the height change saves. An approach to the 4 pump system. What not to do.

Quasi static expressions, useful for preliminary estimates, of dynamic subjects. Simple approach to preventing pulsation and shock in suspect pipe system designs.

P. 41 Establish system acceleration head losses and surge pressure generation level subtraction from suction head addition to discharge force.
P. 42 Factoring in multiplex reciprocating machines
P. 43 Adding friction losses.
P. 44 Adding friction losses.
P. 45 The effects of volumetric inefficiency.
P. 46 Shock generation from velocity jump.
P. 47 Nomogram Frequency vs. Pipe ID to allowable pressure amplitude variation to avoid fatigue.

All together answers the question – do you need pulsation suppression?