Supply Valve Research Articles

A Safety Valve for Emissions Trading

This paper considers the optimal design of an emissions trading program that includes a safety valve tax that allows pollution sources to escape the emissions cap imposed by the aggregate supply of emissions permits. I demonstrate that an optimal hybrid emissions trading/emissions tax policy involves a permit supply that is strictly less than under a pure emissions trading scheme and a safety valve tax that exceeds the optimal pure emissions tax as long as expected marginal damage is an increasing function. While the expected level of emissions under a hybrid policy may be more or less than under pure emissions trading or a pure emissions tax, under the assumption that uncertainty about aggregate marginal abatement costs is symmetric the most likely outcome is that emissions will turn out to be less under the hybrid. Finally, a steeper expected marginal damage function calls for higher permit supply and safety valve, which reduces expected aggregate emissions and the probability that the safety valve will be employed.

Simulation and experimental verification of solenoid valve characteristics for semi-active dampers

This paper deals with mathematical modelling and experimental verification of the steady state and transient characteristics of a solenoid valve required for the design and modelling of a two-state semi-active damper. Valve suppliers do not provide such characteristics. Experimental verification of a steady state mathematical model was performed on a hydraulic test bench. A transient response model was verified using a specially designed semi-active damper. Correlation between models and measured characteristics is acceptable and sufficiently accurate to be used in vehicle dynamics simulation for semi-active suspension design. Fluid compressibility has a significant influence on the valve's transient characteristics.

819 ダム利水放流設備の副ゲート用空気弁の自励振動

819 ダム利水放流設備の副ゲート用空気弁の自励振動

An experimental investigation on a fluidized motion conveying system

The paper presents a description and the performance characteristics of a 3.7 m long fluidized motion conveying system, which transports the dry particulate materials through closed conveying channel section at different conveyor inclinations. The conveying capacity of the system has been investigated using coal ash of median particle size 108 μm as the solid material. Data on the effect of operating superficial air velocity, channel inclination, and the material supply valve opening on material mass flux, plenum chamber pressure and the material bed depth have been presented. It is found that the increase in the operating superficial air velocity increases the material mass flow rate, which finally reaches an asymptotic value at about 1.5–1.7 U mf. It is observed that the plenum chamber pressure is independent of the flow resistance offered by the moving material bed, and is only dependent on the supply of the airflow rate into the plenum. The solids mass flow rate decreases as the conveyor orientation changes from downward to upward direction. Further, the upward inclination of the conveyor requires a higher operating superficial air velocity to start the material flow, and also increases the material bed depth in the channel. The increase in the opening of material supply valve increases both the material mass flux and the bed depth in the channel for all the cases of the conveyor inclinations. The flow visualization in the horizontal and upward incline cases of the conveyor shows that the pulsatory flow mode plays a major role in the transport of the material, whereas, only sliding bed/non-pulsatory flow mode exist in the down-incline of the conveyor. The observed flow patterns have been categorized and classified in terms of flow regimes.

KSB BUYS MAJORITY STAKE IN BOMBAS ITUR

German pump and valve supplier KSB has acquired an 80% controlling share of Bombas Itur SA, the Zarautz, Spain-based pump maker. This is a short news story only. Visit www.worldpumps.com for the latest pump industry news.

Small thermophotovoltaic prototype systems

In an earlier paper we reported on a small grid-connected thermophotovoltaic (TPV) system consisting of an ytterbia mantle emitter and silicon solar cells with 16% efficiency (under solar irradiance in standard test conditions, STCs). The emitter was heated up using a butane burner with a rated thermal power of 1.35 kW (referring to the lower heating value). This system produced an electrical output of 15 W, which corresponds to a thermal to electric (direct current) conversion efficiency of 1.1%. In the interim, further progress has been made, and significantly higher efficiencies have been achieved. The most important development steps are: (1) the infrared radiation-absorbing water filter between emitter and silicon cells (to protect the cells against overheating and against contact with flue gasses) has been replaced by a suitable glass tube. By doing this, it has been possible to prevent losses of convertible radiation in water. (2) Cell cooling has been significantly improved, in order to reduce cell temperature, and therefore increase conversion efficiency. (3) The shape of the emitter has been changed from spherical to a quasi-cylindrical geometry, in order to obtain a more homogeneous irradiation of the cells. (4) The metallic burner tube, on which the ytterbia emitter was fixed in the initial prototypes, has been replaced by a heat-resistant metallic rod, carrying ceramic discs as emitter holders. This has prevented the oxidation and clogging of the perforated burner tube. (5) Larger reflectors have been used to reduce losses in useful infrared radiation. (6) Smaller cells have been used, to reduce electrical series resistance losses. Applying all these improvements to the basic 1.35 kW prototype, we attained a system efficiency of 1.5%. By using preheated air for combustion (at approximately 370 °C), 1.8% was achieved. In a subsequent step, a photocell generator was constructed, consisting of high-efficiency silicon cells (21% STC efficiency). In this generator, the spaces between the cells were minimized, in order to achieve as high an active cell area as possible, while simultaneously reducing radiation losses. This new system has produced an electrical output of 48 W, corresponding to a system efficiency of 2.4%. This is the highest-ever-reported value in a silicon-cell-based TPV system using ytterbia mantle emitters. An efficiency of 2.8% was achieved by using preheated air (at approximately 500 °C). An electronic control unit (fabricated of components with low power consumption, and including a battery store) was developed, in order to make the TPV system self-powered. This unit controls the magnetic gas supply valve between gas supply cylinder and burner as well as the high-voltage ignition electrodes. Both the control unit’s own power consumption and the battery-charging power are supplied directly by the TPV generator. A small commercial inverter is used to transfer excess power to the 230 V grid.

A201 Tilt Control System for Railway Vehicles Using Air Springs

In recent years, there has been growing needs to improve maximum speed on curved tracks. For this purpose, there are many tilting systems. However, vehicles that have special tilting mechanism, are much different from the ordinary ones and expensive. Thus we have developed a tilt control system that is constituted from the ordinary car body and bogie truck with less remodeling. Therefore the maximum tilting angle of this system is restricted to 2 degrees. This system mainly consists of a Controller, Air supply valves, Exhaust valves and Height sensors. The control method is programmed. The tilting operation is performed by the controller, which all data of the curved tracks have been memorized. The location of the vehicle is measured by the tachometer generator and the devices (ground coil) that are attached on the sleeper in order to correct running position. From several running test results, we confirmed that stationary lateral acceleration of car body was reduced by tilt control. The running stability and riding comfort was also adequate so the vehicle equipped with this system could run rapidly than the vehicle with the former restricted speed limit on curved track.

Rotork supply valve actuators for Dutch environment projects

Rotork has just won two contracts to supply its products to innovative, environmentally friendly projects in the Netherlands. The first project is a pioneering district heating scheme in the Westpoort area of Amsterdam. The second is a clean-up project on the Ketelmeer (Kettle Lake) situated a short distance away at the mouth of the River IJssel.

Comment mettre en évidence, corriger et prévenir l'hypoxie tissulaire chez les malades de réanimation ?

La rétropollution du circuit de distribution d'O2 par l'Air médical et vice versa, qui est la pollution la plus fréquente, pose essentiellement des problèmes en salle d'opération et en réanimation néonatale. En cours d'anesthésie elle comporte un risque d'hypoxie, dans la mesure où les poumons sont ventilés avec un mélange Air-N2O (au lieu de O2-N2O), donc à une FlO2 inférieure à 0,21. En réanimation néonatale elle entraîne l'administration d'un mélange O2-O2 (au lieu de Air-O2), donc avec une FlO2 de 1 quand la rétropollution est totale. Ce travail envisage les causes, le diagnostic et la prévention de ce type de rétropollution.A defective Air/O2 mixer of a ventilator located downstream of the gas outlets of two pipelines is a potential cause of retropollution. Retropollution of O2 with Air or vice versa carries a risk of either a) a hypoxic gas mixture delivery during anaesthesia, including O2-N2O administration, when the O2 pipeline supplies Air instead of O2, or b) a hyperoxic gas mixture delivery in the intensive therapy unit for neonates during administration of a O2-Air mixture, when the Air pipeline supplies O2 instead of Air. A defective O2/N2O flowmeter-mixer of an anaesthesia machine, with N2O flow control by O2 through a differential pressure manometer, can cause retropollution of O2 supply pipeline with N2O or vice versa.The prerequisite for retropollution is the association of three events: build-up of a pressure difference between the two gas lines; defective or absent back-flow check valve in the circuit of the gas at a lower pressure; one of the following defects: a) the pressure equilibrating valves of the mixer cannot amend the pressure difference and allow a gas reflow at the gas mixture outlet; b) leak in the diaphragm of a pressure equilibrating valve; c) defective bypass supply valve. The optimal means for the recognition of a pipeline contamination by another gas is the O2 analyzer, especially in anaesthetic areas where the presence of N2O and Air carries the risk of a hypoxic gas mixture delivery. The mixer or flowmeter-mixer responsible for retropollution can be recognized in plunging successively the various quick couplers underwater into a glass, while the others remain connected to their outlets and the mixer set at a O2 concentration of 50 vol % or the flowmeters set at a similar flow. In case of retropollution, the gas reflow produces bubbles.It is recommended: a) in anaesthetic areas to set the O2 pressure at about 0.2 bar above that of Air and the latter at a pressure of about 0.2 bar above that of N2O; b) in intensive therapy units for neonates, to set the Air pressure at about 0.2 bar above that of O2; c) in all areas to disconnect from the gas outlets the devices equipped with a mixer or a flowmeter-mixer when not in use.

Defective gas mixers, a cause of retro-pollution of medical gas distribution pipelines

A defective Air/O2 mixer of a ventilator located downstream of the gas outlets of two pipelines is a potential cause of retropollution. Retropollution of O2 with Air or vice versa carries a risk of either a) a hypoxic gas mixture delivery during anaesthesia, including O2-N2O administration, when the O2 pipeline supplies Air instead of O2, or b) a hyperoxic gas mixture delivery in the intensive therapy unit for neonates during administration of a O2-Air mixture, when the Air pipeline supplies O2 instead of Air. A defective O2/N2O flowmeter-mixer of an anaesthesia machine, with N2O flow control by O2 through a differential pressure manometer, can cause retropollution of O2 supply pipeline with N2O or vice versa. The prerequisite for retropollution is the association of three events: build-up of a pressure difference between the two gas lines; defective or absent back-flow check value in the circuit of the gas at a lower pressure; one of the following defects: a) the pressure equilibrating valves of the mixer cannot amend the pressure difference and allow a gas reflow at the gas mixture outlet; b) leak in the diaphragm of a pressure equilibrating valve; c) defective bypass supply valve. The optimal means for the recognition of a pipeline contamination by another gas is the O2 analyzer, especially in anaesthetic areas where the presence of N2O and Air carries the risk of a hypoxic gas mixture delivery. The mixer or flowmeter-mixer responsible for retropollution can be recognized in plunging successively the various quick couplers underwater into a glass, while the others remain connected to their outlets and the mixer set at a O2 concentration of 50 vol% or the flowmeters set at a similar flow. In case of retropollution, the gas reflow produces bubbles. It is recommended: a) in anaesthetic areas to set the O2 pressure at about 0.2 bar above that of Air and the latter at a pressure of about 0.2 bar above that of N2O; b) in intensive therapy units for neonates, to set the Air pressure at about 0.2 bar above that of O2; c) in all areas to disconnect from the gas outlets the devices equipped with a mixer or a flowmeter-mixer when not in use.

力平衡型ノズルフラッパ式電空圧力変換器空気圧回路の特性解析 第二報 圧力流量特性の理論解析

This paper centers on the theoretical analyses of the pressure versus the flow characteristics of a force -balance nozzle-flapper type pneumatic pressure control proportional valve. The influence of the flow force and effective area of the diaphragm, regarding the pressure versus the flow characteristics, have be studied. Especially, the effects of the radii of the corner rounding of the disk and casing wall have been researched. It has been clarified that the main reason for a pressure decrease in the valve characteristics is due to the change in the effective diaphragm area according to the displacement of the supply valve, and that the flow force may have a slight effect on the characteristics at the time the valve setting pressure is low.

Characteristics of Spring-Type Shock Absorber for Water Hammer.

Recently, lever-type water supply valves have been used in many applications. They can be opened and closed quickly and are easy to operate. On the other hand, water hammers are often created when the valve is closed quickly. We devised a spring-type shock absorber with venturi tube for a water hammer. The aim of this paper is to describe characteristics of the water hammer and shock absorber by experiment and numerical simulation. From the computer simulation, we determine the characteristics of the water hammer and shock absorber, including not only the pressure displacement but also the flow velocity and piston displacement inside the shock absorber.

Static characteristics of a pneumatic pressure control proportional valve with nozzle-flapper mechanism

The paper is concerned with experiments and simulations of the static characteristics of the valve which is a force balance type pneumatic pressure control proportional valve with a nozzle flapper mechanism. It is recognized that the input-output characteristics of the valve has excellent linearity and the characteristics of output pressure versus nozzle flapper clearance look like those of a relay. The effects of the valve parameters on the valve pressure-load flow characteristics are discussed here also. According to the results of the simulations, it is confirmed that the fluid force influencing on the supply valve should be considered.

Investigation of Sprinkler System Failures

The writer discusses the performance of automatic sprinkler systems, and their occasional failure to extinguish or control a fire when there is no obvious reason. Obvious reasons would include a shut water supply valve, a broken water main, an empty water tank, or any other water supply failure. This paper goes beyond the obvious.

Reliability assessment of emergency exhaust system in a pool-type research reactor

The reliability of an extract system in a swimming-pool-type research reactor has been assessed. A global fault-tree analysis technique has been utilized. The basic event reliability data is based on both generic and reactor specific informations. The unavailability of the extract system is quantified in terms of the unavailability of the various functional requirements of the system. The unavailability is expressed as the probability of failure on demand. The computer system unavailability is determined from the minimal cutsets of the system. It is found that only three events have a major contribution to the top event, i.e., failures of compressed air supply, electric power supply and solenoid valve. A sensitivity analysis is performed to show the effects of variations in the data values of the dominant cutsets. An uncertainty analysis was also performed on the fault tree. The evaluations show that the reactor extract system lacks diversity and redundancy in most of its components. It is tolerant of most minor degradations, as these are taken care of by the operating policies and procedures. However, it can not tolerate common cause failures, e.g., simultaneous compressed air and electric power supply failure. Based upon the results obtained some recommendations are made.

Optimal Control Theory Applied to a Pump With Single-Stage Electrohydraulic Servovalve

Optimal control theory is applied to the design of a pressure regulator for an axial piston pump and single-stage electrohydraulic valve combination. The control valve has been modeled and an optimal control law has been formulated. The time response curves due to a step input inflow rate and in current input to the servovalve have been obtained for the open loop and for the optimal control system. Comparison of the results has been made with previous work in which the supply valve to the swashplate actuators was not modeled. It is shown that controlled system modeling of the servovalve significantly improves system performance in terms of response frequency and pressure peaks.

Noise attenuation in power plant control valves—past, present, and future

Noise measurement and control in power plant valves have seen significant advances in the past several years. Aerodynamic noise in control valves is now predictable within a fairly wide range of variables in fluids, while hydrodynamic noise (principally from cavitation) prediction is still somewhat limited in application. A great variety of proprietary and nonproprietary means of noise control for valving now exists. The evolution of noise controls and devices has been from all segments of the using, supplying, and consulting industries and significant further advances are possible. This is particularly true in the realm of high recovery valves, emergency vent valves, and cavitation prediction and control devices. Valve suppliers are detecting a higher level of sophistication among their users with a pronounced tendency to specify only that degree of noise control necessary for a particular application. Examination of several case histories indicates the extremely high cost penalties inherent in overspecifying acceptable levels of control valve noise.

Remote control roof bolting : Short description of an electrohydraulic system consisting of a light-weight low-voltage power supply, connecting lead, and electrohydraulic proportional valves on the bolter MIN. MAG. V129, N6, 1973, P562

Remote control roof bolting : Short description of an electrohydraulic system consisting of a light-weight low-voltage power supply, connecting lead, and electrohydraulic proportional valves on the bolter MIN. MAG. V129, N6, 1973, P562