Valve Seat Research Articles

Design and theoretical simulations of nano check valve constructed of graphene sheets

The unidirectional flow of nanofluids holds paramount importance in numerous nanofluidic applications. However, there remains a void in the practical implementation of a nano check valve specifically designed for ensuring such unidirectional flow. In this work, a nano check valve consisting of a diaphragm and a valve seat is designed and its forward opening and reverse shutoff processes are investigated using molecular dynamic simulations. Additionally, the effects of the modified groups of the diaphragm of the nano check valve are studied. The results demonstrate that the nano check valve can be opened efficiently under a certain forward differential pressure. Besides the differential pressure, the interaction between diaphragm and water molecules contributes to the opening process. Conversely, the non-bonding interaction between diaphragm and the valve seat prevents the opening. The reverse shutoff simulations reveal that the reverse shutoff function can be achieved under the backward pressure even when the nano check valve is firstly opened. It is observed that the ratio of hydroxyl to hydrogen groups on the edge of diaphragm has a significantly effect on the opening pressure due to the non-bond interaction of diaphragm and water molecules. This suggests that the opening pressure of the nano check valve could be regulated by changing the modifier groups.

Assessment of Contact Pressure Occurred on Metal Seat to Ensure Valve Seat Tightness

Assessment of Contact Pressure Occurred on Metal Seat to Ensure Valve Seat Tightness

EXPERIMENTAL INVESTIGATION INTO MAGNETORHEOLOGICAL FINISHING OF POLYMER VALVE SEAT SURFACE FOR BALL VALVE PERFORMANCE

A polymer valve seat is an essential component of ball valves. However, a gas pipeline valve leakage during the gas or oil transportation process causes major issues. Therefore, the fine finishing of the polymer valve seat is important. This work describes the effect of the magnetorheological finishing (MRF) process on the surface characteristics of the polymer valve seat. To achieve a finely finished polymer valve seat surface, the best process parametric combination of current, workpiece rotational, and tool rotational speed are obtained using the response surface methodology. The optimum process parameters are further used to enhance surface characteristics (including surface roughness, microhardness, and surface morphology) through fine finishing. Using the optimum process conditions, the surface roughness was reduced to 110[Formula: see text]nm from 570[Formula: see text]nm in 140[Formula: see text]min of finishing on a 4878[Formula: see text]mm2 surface area of the polymer valve seat. The circularity of the valve seat surface’s dimensional correctness is investigated further. The current MRF process can fine-finish the polymer valve seat surface consistently, resulting in improved surface characteristics and functional performance.

Butterfly valve erosion prediction based on LSTM network

When valves and pipelines are used, erosion wear is a major concern. Erosion wear can lead to equipment downtime, material replacement, and other issues, as well as seal surface failure. The research delves into the phenomenon of erosion in butterfly valves, crucial components utilized across diverse industrial sectors. Erosion primarily affects the valve's disc and seat regions, leading to premature wear and compromised performance. To address this issue, the research employs computational fluid dynamics (CFD) and machine learning techniques, including long short-term memory (LSTM) and BP neural networks, to predict erosion rates under various conditions (different valve openings and particle diameters). Results indicate that erosion escalates with time and larger valve openings, highlighting the need for proactive maintenance strategies. The LSTM model demonstrates superior predictive capabilities compared to the BP neural network, offering valuable insights for improving butterfly valve design and operational efficiency in industrial settings. Furthermore, to seek a more efficient network configuration, the intelligent search capabilities of the particle swarm optimization (PSO) algorithm have been utilized to systematically explore the optimal network structure parameters. The prediction results highlight the advantages of LSTM in handling time series data, particularly in predicting erosion rates with complex dynamic characteristics.

Analisis Penyebab Kerusakan Mesin Diesel pada Generator Set untuk Tindakan Perawatan di Kapal Tanker MT. Sea Serenity

The generator set on the ship has the function of supplying electrical power needs. MT Tanker Ship. Sea Serenity is one of the ships that delivers goods between islands. In operation, the diesel generator engine on the MT. Sea Serenity sometimes experiences problems resulting in blackouts. This research aims to determine the factors that cause damage as well as appropriate maintenance actions and the method used is trouble shooting. Based on the research results, it is found that the causes of damage are: Engine knock, engine exhaust smoke, problems with the injection pump, worn plunger, damage to delivery valve seat, injection nozzle interference, valve opening pressure too low, engine output unstable, worn piston rings. Maintenance carried out: Injection timing must be adjusted according to ignition sequence, set injection timing, replace plunger and delivery valve seat, set valve opening pressure, replace spring, and clean injection orifice. On unstable engine output, the control rack stroke must be checked. Perform regular oil changes and regular tune ups

Investigation of Valve Seat Cone Angle on Small Opening Direct-Acting Relief Valve Cavitation Noise

Direct-acting relief valves are important pressure-control components in hydraulic systems; however, noise problems are now common. This study aimed to reduce and numerically analyze the valve cavitation and noise using the Zwart–Gerber–Belamri (ZBG) model with the Ffowcs Williams and Hawkings (FW–H) model to optimize the design based on the sound field perspective. First, a direct-acting relief valve flow field model was established to determine the relationship between the seat structure and the degree of cavitation through a CFD (Computational Fluid Dynamics) simulation. Second, sound field analysis was conducted based on the cavitation and non-cavitation flow fields, respectively, and the resulting noise levels were compared. Finally, prototypes of the relief valve were manufactured, and noise levels between the original and optimized valves were compared. The results revealed that cavitation within the relief valve generated noise while optimizing the valve seat cone angle suppressed this phenomenon, thereby reducing the noise emitted by the optimized valve by 18.2 dB compared to the original valve. These findings can serve as a guide for designing and optimizing direct-acting relief valves.

A comprehensive mathematical theory and optimized design of a high-frequency electro-pneumatic variable valve actuator for a camless IC engine

This paper discusses the development of a detailed mathematical theory and its use for the design of an electronically controlled, double-acting Variable Valve Actuation (VVA) mechanism for a camless internal combustion engine, that offers a comprehensive control over the timings and the motion of the valves such that any arbitrary time-variation of the valve lift profile can be obtained at variable rotational speeds of the engine shaft. The developed theory encompasses the thermo-fluid-dynamic as well as the applied-mechanical aspects of the actuator cylinder-engine valve system performance, the dynamics of the valve actuation being characterized by parameters such as valve opening duration, peak lift and seating velocity. The prediction of the mathematical theory compares well with several experimental data sets obtained from an in-house pneumatic VVA set-up. A new design methodology is formulated for determining the appropriate dimensions of the actuator, operating thermodynamic parameters and the electronic control of the various valve events for a desired range of engine rotational speed. Several parameters in the new design philosophy are kept within acceptable ranges established from time-tested data obtained from conventional cam-based valve actuation. For example, a new pneumatic cushioning strategy has been developed that is simple, effective and energy-efficient, and is able to keep the valve seating velocity within an acceptable range (0.08–1.13 m/s). The work also discusses the implementation of several constraints that are necessary for the design of a practically viable pneumatic actuator. The evolution of a design matrix map for the electro-pneumatic VVA is quantified for the engine rotational speed varying up to 5500 rpm.

Failure analysis and numerical simulation of the regulating valve with particle erosion and cavitation erosion in the black-water treatment system

The black-water regulating valve is very easy to be damaged due to the erosion of the key components, such as valve spool and valve seat. This work presents the failure analysis of the spool and seat of regulating valve in the black-water treatment system. Scanning electron microscopy and X-ray energy-dispersive spectrometer were used to detect the morphology and chemical compositions of failure valve samples. The computational fluid dynamics method was also adopted to simulate the medium flow characteristics in black-water regulating valve. The results show that most erosion areas of the valve occur at the spool-seat throttle zone. The erosion profile is mainly manifested in plastic deformation pits, cutting abrasions, furrows, pinhole pits and impact pits. The particles and cavitation bubbles move toward the throttle zone driven by black-water medium, causing particles impact and bubbles collapse. The particle flow velocity in the throttle zone of the valve is between 50 and 175 m/s, while the maximum velocity can reach 175 m/s. The valve suffered severe particle erosion and cavitation erosion under the particle impact and bubble collapse, finally resulting in its failure.

Development of conformable cryogenic valve seats for resilience to foreign object debris

Cryogenic valve sealing technology is notoriously more challenging than traditional fluids due to the combination of small atoms and molecules with extreme temperature and pressure profiles. Recently, flexible polymeric films folded into origami demonstrated considerable resilience to mechanical failure in the cryogenic extreme. Fluorinated polymers such as Polytetrafluoroethylene (PTFE) are observed to mechanically flex and not plastically deform in cryogenic conditions. This paper explores a new cryogenic valve sealing paradigm which uses multiple conformable polymer layers to provide constant seat mating surface area at cryogenic conditions. Stacking these thin discs in series with a spacer allows maximum bend around the seat while creating multiple sealing surfaces. Experimental measurements of leakage rates with and without the presence of Foreign Object Debris (FOD) are compared with traditional re-closable pressure relief valves. Conformable cryogenic valve seats have the potential to be more repeatable, decrease leakage rates from differing coefficients of thermal expansion, hysteresis, and FOD when compared to traditional market valves.

Badania turbulentnego przepływu płynu w pompach głębinowych w celu poprawy bezpieczeństwa środowiskowego

When the plunger moves downwards, the local hydraulic resistance in the injection system causes a hydraulic force from the bottom upwards, which prevents the plunger from falling freely in the cylinder and is the source of the bending of the pump rod column. For this reason, the plunger takes an eccentric position in the cylinder and presses against it, delaying the plunger fall from the head of the balancer of the rocking machine and disturbing coaxial connection of the stock-discharge valve-plunger. These complications lead to increased wear of the plunger-cylinder pair, breakage of the injection valve cell, broken pump rod column, loss of the plunger stroke, etc. It should be noted, however, that in these tests, the flow factor μ is taken as the hydraulic resistance for determining the pressure loss in the valve assembly, and the valve seat cross-section is calculated. When calculating the friction force in the plunger-pressure valve system, the loss of pressure in it is taken to be equal to the loss of pressure of the valve unit. As is known, the downhole pump suction and injection system is a complex system of local resistance, as it consists of different combinations of elements that strongly affect the overall hydraulic resistance of the unit. It is therefore advisable to adopt the local hydraulic resistance coefficient as the hydraulic resistance of the respective unit. The reliability of downhole pumps in general and their individual components is ensured during their design and manufacture and depends on the design features, the quality of manufacturing of components thereof, assembly of the downhole pump in general and their components, as well as a number of other process indicators.

Experimental investigation of cutting force of powder metallurgy valve guide rod hole

Aiming at the problem of fast wear of machining tools in the special powder metallurgy valve guide rod hole and gasket seat of a certain engine cylinder head, in order to solve the technical problems in the cutting force (CF) of this kind of powder metallurgy materials, different tools are used and the analysis is carried out under different cutting test conditions. The cutting force law and surface roughness change law of similar powder metallurgy materials are determined to determine the appropriate tool materials and processing parameters. The experimental results show that under the same processing conditions, ceramic tools will suffer less than cemented carbide tools and cutting force can obtain a smaller surface roughness. In addition, the mass production process of valve seat, the blade material is ceramic knife.

PLUG KNOT PROCESSING OF GLOBE VALVE

Globe valves are essential components in fluid control systems, widely used in various industries for regulating flow. This paper provides an overview of globe valves, focusing on their design, operation, and applications. The distinctive spherical body shape of globe valves allows for precise control of fluid flow through the system. The paper discusses the internal components of globe valves, including the valve stem, disk, seat, and bonnet, highlighting their roles in the valve's functionality. Furthermore, it examines different types of globe valves, such as straight pattern, angle pattern, and Y-pattern valves, along with their specific applications and advantages. Additionally, the paper addresses common materials used in globe valve construction, emphasizing the importance of selecting materials suitable for the operating conditions and the fluid being controlled. Lastly, maintenance and troubleshooting tips are provided to ensure optimal performance and longevity of globe valves in industrial settings. Emphasis is placed on their operational mechanisms, wherein the movement of the plug, controlled by the stem, modulates flow rates precisely. Overall, this paper serves as a comprehensive guide to understanding globe valves and their significance in fluid control systems Keywords: Globe vаlve (type) , valve body, bonnet, plug , disk ,valve seat, stem.

Numerical investigations of the influences of valve spool structure on the eccentric jet flow characteristic in high-pressure angle valves

High-pressure angle valves have suffered from eccentric jet flow characteristic in the diffuser pipe section due to the inherent structures and throttling effect. The eccentric jet flow will continuously scour the valve body and lead to washout on the side wall of the valve seat, largely impacting the valve service life and safety. With regard to this issue, this paper has conducted a numerical characterization study to investigate the influences of valve spool structures including the prototype, parallel and spherical spools on the eccentric jet flow in the first diffuser pipe section of a high-pressure angle valve. Results show that the parallel and spherical valve spool structures can achieve a lower pressure difference across the pipe section than the prototype spool structure, while the spherical spool has shown the minimum pressure difference in the first diffuser pipe section. Moreover, compared with the prototype and parallel spools, separated flows are distributed more uniformly on both side walls in the first diffuser pipe section for the valve with the spherical spool. The relative uniformly distributed separation vortexes makes the high-speed mainstream along the pipe center line and can successfully mitigate the eccentric jet flow. The motivation of this work is to reveal the influencing mechanisms of spool structures on the eccentric jet characteristic in high-pressure angle valves and provide useful guidelines for advanced angle valve design with low erosion and long service life.

Reliability analysis of respirators based on the analytic hierarchy process and multicriteria decision-making

This study examined the reliability of respirators using hierarchical analysis and multicriteria decision-making. The hierarchical structure, which consists of three assessment criteria and six product assemblies as decision possibilities, reveals that the priority of evaluation criteria follows the trend of cost, complexity and technology. Face-piece, triple-piece and visor assemblies have the highest failure rate, according to an analysis of product reliability at the assembly level. However, according to the analysis at the parts level, the most likely failures are found in the face-piece, upper and lower visor frames, visor, head-harness, exhalation valve disc and exhalation valve seat. In addition, the Weibull distribution function (with a shape parameter >1) can be utilized to predict product reliability. Among the six defined product assemblies, according to the sensitivity analysis, the overall weight of the triple-piece assembly and the visor assembly has the most sensitivity to changes in the priority of evaluation criteria.

Simulation study on the cavitation distribution in the ball valve of a common rail injector

A transient-state numerical simulation is conducted to investigate the cavitation flow in the ball valve of a common rail (CR) injector. The computational fluid dynamics (CFD) software, employing the RANS turbulence model, is employed for this purpose. The study aims to analyze the characteristics and underlying causes of the uneven distribution of cavitation in the ball valve. The results reveal a significant occurrence of cavitation, exhibiting an uneven distribution along the walls of both the ball and the valve seat. Notably, the initiation position of the intense cavitation region on the wall of the ball is observed to lag behind that on the wall of the valve seat. The intense cavitation region on the wall of the ball is found to reside behind the sealing surface of the ball valve. The intense cavitation region on the wall of the ball is located behind the sealing surface of the ball valve. This region experiences flow separation caused by main flow detour, resulting in the formation of vortices that entrapped the cavitation cloud, thus fostering the development of intense cavitation. Conversely, the intense cavitation region on the wall of the valve seat originates from the entrance of the ball valve. This can be attributed to the sudden change in geometry at the entrance, leading to a significant pressure drop and inducing cavitation based on geometric factors. Furthermore, the stagnation effect caused by the ball exacerbates the discrepancy in the distribution of the intense cavitation region between the ball and the valve seat.

METHODOLOGY FOR STUDYING ACCURACY PARAMETERS
 IN THE PROCESS OF RESTORING THE VALVE SEATS

In this article a methodology for researching the parameters of forming in the process of processing valve seats
 of an internal combustion engine valve timing gear in an automobile repair industry was described.
 The practical implementation of this methodology was carried out using laser triangulation sensors based on the
 developed device for boring valve seats. Experimental dependences of the cutting tool displacement on various processing modes were obtained. Practical recommendations were made on the selection of cutting mode ranges to ensure
 the required precision parameters when restoring valve seats.

Analysis of disc movement during the closing process of axial flow check valves

In a long-distance pipeline system, when the pump is stopped, the axial flow check valve will suddenly close under the pressure difference force of the medium, and the instantaneous valve disc will collide and impact the valve seat at a certain speed, which will have a certain impact on the structural strength and service life of the check valve. This article uses explicit dynamics to simulate the movement process of the instantaneous valve disc when it is completely closed and analyzes the velocity of the valve disc after the collision. Based on the spring damping model theory, the velocity of the valve disc after collision is derived. After error analysis, the reliability of numerical simulation has been verified, which has a certain guiding significance for the practical application and design improvement of axial flow check valves.

A high resolution and wide range valve for micronewton cold gas thrusters.

Numerous scientific satellites require micronewton thrusters for compensating environmental disturbances. The mass flow control proportional valve plays a crucial role in precisely regulating the thrust. To meet the high resolution and wide range requirements of the thrusters, this paper introduces a novel proportional valve with two sets of independently controllable piezoelectric stack. One set of the piezo-stack is used to compensate the stroke loss of the valve core, mainly caused by the deformation of the valve seat. The valve sealing mechanism is carefully analyzed to reduce the stroke loss. Another set of the stack works as the primary actuator, enabling the high mass flow control resolution. Two sets of independently controlled piezoelectric stacks not only expand the range and improve the range ratio but also provide redundancy and enhance reliability. This means that the actuator can still operate at lower ranges even if one piezo-stack is damaged. The piezo-actuators are assembled using U-shaped connectors, creating a compact and space-efficient overall design. Experimental tests have been conducted to verify the performance of the valve, which demonstrated a mass flow range of 0-675 μg/s with a resolution better than 0.1 μg/s and a flow noise below 0.1 μg/s/Hz1/2 at 0.1 mHz-1Hz.

Retracted: Influence of Sulfur and Additives on Wear of Exhaust Valve Seat of Cylinder Head

Retracted: Influence of Sulfur and Additives on Wear of Exhaust Valve Seat of Cylinder Head

Design and development of a cryogenic J-T valve for a 2 K cryostat with a single cryocooler

Abstract A cryogenic Joule-Thomson (J-T) valve for a 2 K cryostat cooled with a G-M cryocooler has been developed to continuously supply superfluid helium. Saturated liquid helium flowing through the valve transitions to superfluid helium below 2 K because of the J-T effect. The heat leak, sealing performance and the J-T effect of the valve were tested experimentally and analyzed. To reduce heat leak in the 2 K range, two thermal anchors were installed in the first and second cooling stages, respectively, resulting in 89.93% reduction of useful work loss. A unique sealing structure was developed for the J-T valve and was tested at both room temperature and liquid nitrogen temperature, yielding leak rates of 3 × 10-9 Pa· m3/s and 3 × 10-4 Pa· m3/s, respectively. The corresponding valve needle and seat structure were designed based on the flow resistance equation. The J-T effect of the valve in 2 K cryostat was tested at various valve openings. The cryostat can operate at 1.64 K with no load and provide 0.143 W cooling power at 2 K.