Pressure Regulator Valve Research Articles

Location and Calibration of Valves in Water Distribution Networks Using a Scatter-Search Meta-heuristic Approach

Recently, there has been an increase in the use of meta-heuristic techniques addressing water distribution network design and management optimization problems. The meta-heuristic approach applied to water distribution systems has provided interesting results both for optimum pipe diameter sizing and for the location and management of network pressure control devices (i.e., pumps and valves). Regarding the insertion and calibration of pressure regulation valves, the use of meta-heuristic techniques is relatively recent. We search to strategically placing the valves in order to achieve pressure control in the network and, therefore, the valves must be calibrated in relation to water demand trends over time. In the Pressure Reference Method (PRM) described in this paper, the search for valve location is restricted to pipe-branch sets defined on the basis of hydraulic analysis and considering the range between minimum and maximum acceptable pressures in the network. In the PRM approach, the Scatter-Search (Glover and Laguna, 1997) meta-heuristic procedures are applied to obtain the optimal location and calibration of valves in the water distribution network.

自動減圧弁と定流量弁を含むパイプラインシステムにおける自励振動の発生例とその抑制対策

自動減圧弁と定流量弁を含むパイプラインシステムにおける自励振動の発生例とその抑制対策

Multi-Element Unstructured Analyses of Complex Valve Systems

The safe and reliable operation of high-pressure test stands for rocket engine and component testing places an increased emphasis on the performance of control valves and flow metering devices. In this paper, we will present a series of high-fidelity computational analyses of systems ranging from cryogenic control valves and pressure regulator systems to cavitating venturis that are used to support rocket engine and component testing at NASA Stennis Space Center. A generalized multi-element framework with submodels for grid adaption, grid movement, and multi-phase flow dynamics has been used to carry out the simulations. Such a framework provides the flexibility of resolving the structural and functional complexities that are typically associated with valve-based high-pressure feed systems and have been difficult to deal with using traditional computational fluid dynamics methods. Our simulations revealed a rich variety of flow phenomena such as secondary flow patterns, hydrodynamic instabilities, fluctuating vapor pockets, etc. In the paper, we will discuss performance losses related to cryogenic control valves and provide insight into the physics of the dominant multi-phase fluid transport phenomena that are responsible for the “choking-like” behavior in cryogenic control elements. Additionally, we will provide detailed analyses of the modal instability that is observed in the operation of a pressure regulator valve. Such instabilities are usually not localized and manifest themselves as a system-wide phenomena leading to an undesirable chatter at high flow conditions.

RESPIRATION RATE MEASUREMENT OF FRESH PRODUCE USING AN AUTOMATED FLOW-THROUGH SYSTEM

This study was conducted to develop an automated measuring system for the respiration rates of fresh produce held under various gas compositions. This system was based on the flow-through measurement method. The system has two main parts; gas mixture generation, and gas analysis. The gas mixture generator consisted of precision pressure regulators and metering valves. The flow rate of O 2 , CO 2 and N 2 (balance gas), which were supplied from cylinders, was controlled by the precision pressure regulator and metering valve to obtain the desired gas mixture. The gas analysis part consisted of a multi-position valve, sample loop and gas chromatograph. The gas flow line was connected to the multi-position valve, which separated inlet and outlet from the gas mixture chamber. Therefore, it was possible to analyze gas samples by gas chromatography using the flow-through method. The gas concentration generated by the gas mixing system was within ± 0.2% of the target concentrations. In an empty chamber, the difference of inlet and outlet gas concentration was 0.1%. When gas samples were analyzed three times at each gas flow line (inlet and outlet), the measuring reproducibility was ± 0.03%. The system successfully measured the respiration rates of tomato fruit.

Fast and Accurate Pressure Control using On-Off Valves

Pneumatic cylinders and pneumatic muscles are lightweight, clean and multifunctional actuators, requiring pressureregulating valves for positioning. To use them in mobile applications commercial pressure-regulating valves are quite heavy and rather slow. Therefore an intelligent controlled array of fast switching on-off valves is presented as an alternative. The speed of the on-off valves determines the performance of the pressure-regulating valve. To reduce the opening time of the valves, a higher voltage is applied on the coil for a short time. The influence of this method on the heating of the valve will be discussed. A diode, which drains away the electromagnetic power from the coil, reduces the closing time. When working with pneumatic muscles, it is in some cases justified to remove the internal spring to enhance the opening time. A modified bang-bang controller, with more than one level and a dead zone is presented. Experimental results on a fixed volume are discussed. A special designed collector combines 6 on-off valves into a lightweight pressure control valve island, which is perfectly suited for walking robots such as the pneumatic actuated biped Lucy.

Curvas de desempenho de válvulas reguladoras de pressão novas e com diferentes tempos de utilização

O desempenho de uma válvula reguladora de pressão, fabricada pela Fabrimar, Modelo Exact-20-Ref. RP-3-20-3/4"FF, utilizada em pivô central, foi avaliado em laboratório, conforme as normas ISO (1993). Este trabalho foi desenvolvido no Laboratório de Irrigação do Departamento de Engenharia Rural, ESALQ/USP, utilizando-se reguladores de pressão novos e com diferentes tempos de emprego no campo. As curvas de desempenho das válvulas novas satisfizeram as condições exigidas pela norma, caracterizando o regulador como do tipo A, para as velocidades de referência de 0,5 m s-1 (vazão de 0,57 m³ h-1) até 4,0 m s-1 (vazão de 4,50 m³ h-1) e várias pressões de entrada, sendo também elaborado um modelo estatístico para a pressão de saída do regulador novo, com uma vazão e uma pressão de entrada. Foram coletadas, de diversos sistemas tipo pivô central e de diferentes vãos, válvulas reguladoras de pressão do mesmo modelo, que possuíam tempos de uso de 2000, 2500, 6000, 8500, 9000 e 10000 h e, também, com diferentes qualidades de água utilizadas. Os ensaios seguiram os mesmos padrões dos novos, realizando-se uma análise estatística dos dados. Apesar dos desgastes provocados pela água de má qualidade e dos vazamentos apresentados, o desempenho hidráulico das válvulas com tempo de uso até 6000 h, não diferiu do desempenho das novas, para pressões de entrada até 826,3 kPa e velocidades de referência até 2,5 m s-1. O desempenho dos reguladores de pressão com tempos de uso iguais ou superiores a 8500 h, não se manteve semelhante ao do regulador novo, especialmente para pressões de entrada superiores a 481,7 kPa.

A PRESSURE REGULATING SYSTEM FOR VARIABLE IRRIGATION FLOW CONTROLS

It is important for an irrigation system to have a stable constant pressure to obtain efficient water managementfor crops. A simple mechanical flow control system with a pressureregulating valve was investigated for subsurface dripirrigation and small acreage sprinkler irrigation to maintain constant pressure under variable flow conditions. A submersiblepump, booster pump, and centrifugal pump were tested with the control system for the variable flow rates ranging from 9.6to 222.1 L/min and pressure ranging from 69 to 276 kPa. As long as the pumps were able to provide enough flow to maintaina pressure differential of 124 kPa between control system inlet and outlet, the line pressure remained constant and stablethrough the test. Standard deviation of the pressure from the flow control system at 69kPa pressure setting was 0.4 kPa forthe submersible pump, 1.2 kPa for the booster pump, and 3.9 kPa for the centrifugal pump. At the 69kPa pressure setting,the amperage to the booster pump decreased from 11.3 to 8.8 A when the total flow rate in the line decreased from 158.1 to41.2 L/min. The irrigation system with the flow control avoided pressure pulsation and reduced total energy consumption.

Pressure regulator valve by Bondgraph

The Bondgraph represents mechanical, hydraulic and electric components with their power flow in an unified manner and is used here for a three port regulator valve for pressure. It consists of a valve spool and a valve body or casing, and an electric solenoid. The valve assembly has three ports and two variable metering orifices, represented by modulated R-elements. They are the combination of a proportional and a quadratic characteristic, each by separate R-elements. One of them is in conductance causality, the other one in resistance causality and they are on a 1-junction. This gives an algebraic loop that can be broken by a first order element. Even with a closed port, there is some passage, or leakage in the valve due to clearance. The solenoid is non-linear. The whole is represented by a Bondgraph and simulated by the TUTSIM program, where real parameters are used. This leads the valve dynamics much quicker than solving differential equations

A New Endotracheal Tube with a Cuff Impervious to Nitrous Oxide

A New Endotracheal Tube with a Cuff Impervious to Nitrous Oxide

An Analysis of Pressure Regulator Valve by Bondgraph.

From the standpoint of power conservation, bondgraphs represent systems, even those composed of mechanical, hydraulic and electric components, by a unified approach. In this paper, a three-port pressure regulator valve is represented by the bondgraph, in which hydraulic resisters are controlled by orifices having overlap and underlap. The bondgraph of the resisters is constructed with two R-elements consisting of a linear resister and a squared resister. Additionally the effect of mixed air in the oil is easy to analyse by using the initial bondgraph and two additional C-elements. Dynamic behaviour of this regulator valve is obtained easily by bondgraph simulation in comparison with the usual simulation methods.

圧力補償付き可変容量形斜板式ピストンポンプの過渡特性

This paper presents a study on the transient characteristics of a variable-displacement, swash-plate type axial piston pump incorporating a pressure compensator. The effects of design and operating parameters on the surge pressure generated in the outlet line at the time of an instantaneous circuit cutoff, and the settling times of pump discharge pressure and swash-plate angle (i.e., pump flow rate) after instantaneous circuit cutoff and opening were mainly investigated.It was found that the surge pressure was predominantly influenced by the flow resistances in the passages and the pressure override of the pressure-regulating valve, as well as by the volume of the pump discharge line. In addition, the mathematical model of the pump control system presented in this work, in which all variables were expressed by the state equations, and the numerical calculation method for it could be confirmed to be an effective and generally applicable method for the theoretical analysis of the transient characteristics of these systems.

Theoretical analysis and experiment of impact load transmitted into a sphere adjacent to anvil struck by travelling round bar.

The mechanical components of a ball thrust bearing, constant-velocity universal joint, locker arm of a cam driving a cylinder valve and a ball-type pressure-regulating valve, involve the elements of a sphere and an anvil. These are subjected to impact load. In this paper, we suppose a model with the simplest form of only a sphere and an anvil for these complex components. The sphere and anvil are in contact with each other and rest along the straight line joining their centers. When the free-side end of the anvil undergoes the normal collinear impact by travelling around the bar, the impact load transmitted into the sphere adjacent to the anvil is theoretically analyzed by a motion equation and Hertz's contact theory. It is important to find the particle velocity evoked by the arrival of a stress wave at the end of the anvil which is a point contact with the sphere. This particle speed is an initial velocity as the anvil transmits the load into the sphere. The validity of theoretical analysis is confirmed by comparison with an experiment under the same conditions.

Stability and Regulation of a Variable-Displacement Vane-Pump

Pressure fluctuations may develop in the hydraulic system of automatic transmissions, even under steady-state conditions. To analyze this phenomenon, a dynamic model was developed for a system which consists of a variable-displacement vane-pump, a regulator, and a resistive load. The model was linearized and reduced to generate a stability criterion for the pressure-regulation circuit. This criterion determines a critical frequency that the natural frequency of the pressure-regulation valve must exceed to assure stability. This critical frequency depends primarily on the damping of the spool of the pressure-regulation valve and on its position; the latter is a function of the regulation-chamber leakage characteristics. The analysis shows that line pressure, flow and leakage, along with production tolerances and different opening conditions, have a significant effect on the stability of the hydraulic system. Test data support the analysis.

Army Cutworm Control on Wheat, 1982

Abstract This field test was conducted in a dryland wheat field at Tribune, Greeley Co., Kans. Seven insecticidal treatments and an untreated check were replicated three times in a randomized complete block design. Each plot was 10.06 m by 10.06 m with a 1.5-m wide unsprayed buffer separating each plot. Materials were applied as broadcast sprays 20 Apr., with a 9.46-liter compressed air backpack sprayer having a 45.72-cm boom with 3 no. 6X hollow cone nozzles (Spraying Systems). Portable air tanks with a pressure regulator valve supplied a constant sprayer tank pressure of 1.4 kg/cm2 which delivered 159.02 liters of finished spray per ha. Wind velocity was 8 kg/h and air temperature 12.8°C at application. Treatments were evaluated 3 and 7 days posttreatment by counting live cutworms from four 0.09 m2 soil samples to a depth of 10.16 cm in each plot. Soil samples were sifted to increase counting accuracy. Yield determinations were not made because of low army cutworm numbers and severe plant stress from summer drought.

Evaluation of Insecticides to Control Greenbug (Biotype E) on Grain Sorghum, 1982

Abstract This field test was conducted in a dryland field of grain sorghum at the Kans. Br. Agric. Exp. Stn., Garden City, Kans. Ten insecticide treatments and an untreated check were replicated three times in a randomized complete block design. Plots were four rows by 9 m (76 cm row spacing) and were separated by two untreated rows and 1.5-m alleys. Sprays were applied over the row with a 9.46-liter compressed air backpack sprayer having a 45.72-cm boom with 3 no. 6X hollow cone nozzles (Spraying Systems). Portable air tanks with a pressure regulator valve supplied a constant sprayer tank pressure of 1.4 kg/cm2. The sprayer was calibrated to deliver approximately 145 liters/ha. Application was made 17 Aug. at which time plants were in the late boot stage. Temperature at the start of application was 20.6°C and wind velocity was recorded at 8 km/h. Control was assessed by counting live greenbugs on each of four randomly selected plants in each plot at 3 and 7 days posttreatment. Grain yield estimates were obtained from 9.9 row-m samples hand harvested from the center two rows of each plot. Yields were corrected to 12.5% moisture.

Lightning Protection for an Oilfield Automation And Instrumentation System

A description of lightning protection devices in a computer-monitored oilfield automation project located on the south high plains of West Texas near Levelland. Lightning damage was substantially reduced with the present protection system. Introduction For many years, the problem of protecting electrical systems from lightning discharges has plagued power and communications engineers. Only within the past few decades has lightning been a problem to engineers dealing with electrical power systems in oil fields. The problem of lightning protection in West Texas oil fields is unique because of the high concentration of elevated high-voltage lines above flat plains that attract lightning discharges. Most modern, electrically operated oil fields have power distribution systems that are well protected from power distribution systems that are well protected from lightning discharges; and, in many cases, these systems are isolated by sectionalizers and other devices. Even if a portion of a field is disabled by lightning damage, the remainder of the field continues to function normally. This paper concentrates on protecting the low-voltage electronic instrument systems that are very susceptible to even minor voltage surges caused by lightning. In the last several years, the tremendous expansion of oilfield automation and electronic surveillance equipment has required increased emphasis on protecting low-voltage instrument systems from lightning discharges. These systems use DC voltages of near zero to 50 v with 120-v AC-powersources. This paper deals with methods used in a major oilfield automation project to protect various parts of the system from lightning damage. The lightning protection devices discussed are used to protect two of Amoco Production Co.'s computer-monitored oilfield automation projects located on the south high plains of West Texas near Levelland, Tex, plains of West Texas near Levelland, Tex, Fig. 1 shows schematically the automation project operating in one of the locations. This is a secondary waterflood unit with almost 700 wells. The unit is under the surveillance of a computer-monitored oilfield production automation system that utilizes about 1,500 status, production automation system that utilizes about 1,500 status, control, and measurement devices. It has about 150 miles of buried multiconductor cables ranging from 6- t50-pair cables. In this project, "pump-off" controllers are used to control the producing wells, have dry contacts, and indicate satisfactory controller operation and motor status. Water injection wells are controlled by mechanical pressure-regulating valves. The injection rates and pressures are monitored by the computer "reading" amplified signals from turbine meters and pressure transducers. pressure transducers. At satellite tank batteries, the status of tank levels, fire indicators, temperature, and other conditions is monitored with each end device having a set of dry contacts. Producing well tests are obtained by automatically Producing well tests are obtained by automatically switching individual flowlines to fired heater-treaters or separators using electrically operated ball valves. Dry contact meter pulses from these vessels are accumulated by the computer system to determine producing volumes and rates. The telemetry system consists of master and remote telemetry units. Communication between telemetry units is accomplished by frequency modulation using buried copper conductors. JPT P. 1405

Röntgenaufnahmen mit der Buergerschen Präzessionskamera bei Temperaturen zwischen 1000°C und 2000°C

Single crystal photographs at temperatures between 1000°C and 2000°C using a Buerger precession camera can be obtained by heating the crystal with a small gas flame. The temperature of exposure may be controlled by gas pressure and gas flow (pressure regulator and needle valve). Advantages and disadvantages of the device are discussed. X-ray exposures at high temperatures of anorthite (CaAl 2 Si 2 O 8 ) demonstrate the application of the apparatus. The lattice angle α * and the intensity ratios of some reflections show a continuous change at temperatures between 300°C and 1400°C.