Addressing Low Pressure Transients

In this study, pressure transients are triggered by a steel ball, which is released from an upstream reservoir to hit a valve seat and shut off water flow in a horizontal straight copper pipeline. The pressure pulsations, cavitation and gas bubbles growth and collapse in the low pressure water-hydraulic pipeline are recorded by two pressure transducers and a high speed video camera, respectively. In addition, the influences of initial volume of gas bubbles in water and instant leakage in valve are investigated. The experimental results indicate that increasing initial gas bubble volume in water and the instant leakage of the valve will help to reduce magnitudes and numbers of pressure peaks during pressure transients. Then methods to reduce pressure pulsations in pipelines are put forward.

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Study on Pressure Transients in Low Pressure Water-Hydraulic Pipelines

IEEE Access ◽

10.1109/access.2019.2923100 ◽

2019 ◽

Vol 7 ◽

pp. 80561-80569 ◽

Cited By ~ 2

Author(s):

Dan Jiang ◽

Qixia Lu ◽

Yuanming Liu ◽

Dongdong Zhao

Keyword(s):

Low Pressure ◽

Pressure Transients ◽

Pressure Water ◽

Water Hydraulic

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Simulation of Hydraulic Pipeline Pressure Transients Accompanying Cavitation and Gas Bubbles Using Matlab/Simulink

Volume 1: Symposia, Parts A and B ◽

10.1115/fedsm2006-98389 ◽

2006 ◽

Author(s):

Jiang Dan ◽

Songjing Li

Keyword(s):

Mathematical Model ◽

Finite Difference ◽

Finite Difference Method ◽

Difference Method ◽

Gas Bubbles ◽

Simulation Method ◽

Low Pressure ◽

Matlab Simulink ◽

Pressure Transients ◽

The Mathematical Model

In order to predict pressure transients accompanying cavitation and gas bubbles in hydraulic pipeline operating at low pressure, a mathematical model and a simulation method are studied. The mathematical model is based on the two basic equations of motion and continuity. The growing and collapsing of cavitation and gas bubbles accompanying pressure pulsations are modelled to calculate the volumes of cavitation and gas bubbles. The pipeline dynamic friction model is introduced. Meanwhile, a simulation method, using finite difference method and Matlab/Simulink platform, is developed to handle the prediction of pressure transients. Finally an example of fluid transients inside hydraulic pipeline is simulated after a downstream valve is closed rapidly. Simulation results show that, for a certain example pipeline, the mathematical model can handle the prediction of pressure transients accompanying cavitation and gas bubbles in low pressure pipeline. The use of combining finite difference method with Matlab/Simulink platform provides a relatively simple and effective tool to understand the nature of pressure transients accompanying cavitation and gas bubbles.

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Addressing Low Pressure Transients

Volume 8: Operations, Applications, and Components ◽

10.1115/pvp2020-21858 ◽

2020 ◽

Author(s):

Amy Marroquin ◽

Scott Lang

Keyword(s):

High Pressures ◽

Low Pressure ◽

Liquid System ◽

Vapor Pressures ◽

Pressure Transients ◽

Common System ◽

Fluid Transient ◽

Piping Systems ◽

Low Pressures ◽

Potential Issue

Abstract Low transient pressures in piping systems are different in many ways to high transient pressures. While high pressures can obviously burst pipes or damage components, low pressures can collapse pipes, pull in environmental contaminants, bring components out of solution, or induce transient cavitation, a particular concern for hydrocarbon liquids. This paper will use examples of computer modeling to reveal how common system events such as pump trips or valve closures induce low pressure transient waves that have potential to be just as destructive as more intuitive high pressure waves. Fluid transient studies and literature often focus on high pressures, or do not clearly demonstrate how liquids with low vapor pressures (such as many hydrocarbons) can be affected. Even discerning a pipe’s negative pressure rating through codes and standards can be a challenge. It is shown that low pressure transients are a potential issue in any liquid system. It is further demonstrated that “Rule of Thumb” or typical simplified calculations are not sufficient to capture these effects, and cannot be used to properly locate and size equipment.

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Protecting Drinking Water Systems from Low Pressure Transients - A Case Study

Pipelines 2013 ◽

10.1061/9780784413012.001 ◽

2013 ◽

Author(s):

Don J. Wood ◽

Gary Williams ◽

Gewnn Phalempin ◽

Frank K. Snith, III

Keyword(s):

Drinking Water ◽

Low Pressure ◽

Water Systems ◽

Pressure Transients ◽

Drinking Water Systems

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Effects of Electrical Discharges in Low Pressure Gases on the Morphology of Polyethylene Crystals

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100052730 ◽

1974 ◽

Vol 32 ◽

pp. 544-545

Author(s):

L.H. Bolz ◽

D.H. Reneker

Keyword(s):

Power Distribution ◽

Electrical Discharge ◽

Dielectric Breakdown ◽

Ionic Species ◽

Low Pressure ◽

Polymer Surfaces ◽

Electrical Discharges ◽

Adhesive Bonds ◽

Power Distribution Lines ◽

Modification Of The Surface

The attack, on the surface of a polymer, by the atomic, molecular and ionic species that are created in a low pressure electrical discharge in a gas is interesting because: 1) significant interior morphological features may be revealed, 2) dielectric breakdown of polymeric insulation on high voltage power distribution lines involves the attack on the polymer of such species created in a corona discharge, 3) adhesive bonds formed between polymer surfaces subjected to such SDecies are much stronger than bonds between untreated surfaces, 4) the chemical modification of the surface creates a reactive surface to which a thin layer of another polymer may be bonded by glow discharge polymerization.

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Field ion microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100104236 ◽

1988 ◽

Vol 46 ◽

pp. 434-435

Author(s):

Gert Ehrlich

Keyword(s):

Low Temperature ◽

Sample Surface ◽

Low Pressure ◽

Radius Of Curvature ◽

Field Ion Microscopy ◽

Phosphor Screen ◽

Ion Microscopy ◽

Field Ion Microscope

The field ion microscope, devised by Erwin Muller in the 1950's, was the first instrument to depict the structure of surfaces in atomic detail. An FIM image of a (111) plane of tungsten (Fig.l) is typical of what can be done by this microscope: for this small plane, every atom, at a separation of 4.48Å from its neighbors in the plane, is revealed. The image of the plane is highly enlarged, as it is projected on a phosphor screen with a radius of curvature more than a million times that of the sample. Müller achieved the resolution necessary to reveal individual atoms by imaging with ions, accommodated to the object at a low temperature. The ions are created at the sample surface by ionization of an inert image gas (usually helium), present at a low pressure (< 1 mTorr). at fields on the order of 4V/Å.

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