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Due to the need to use very precise manufacturing processes, hydraulic applications are one of the most demanding parts in production. Such a feature requires using molded and properly machined parts. On the other hand, such an approach makes hydraulic parts very heavy and requires the use of large amounts of material. One of the most promising manufacturing technologies that could be a real alternative to hydraulic parts production is additive manufacturing (AM). This paper aims to study how the AM process affects the performance properties of the as-built state, and investigate changes after different types of postprocessing in the case of hydraulic check valves. Based on the obtained results, using proper postprocessing is a crucial feature of obtaining check valves that perform their functions in a hydraulic system. In as-built parts, the surface roughness of the valve seats significantly exceeds the acceptable range (almost nine times—from 4.01 µm to 33.92 µm). The influence of the surface roughness of the valve seats was verified via opening pressure and internal leakage tests based on ISO standards. The opening pressures in all tested samples were similar to those in the conventionally made counterparts, but in the case of internal leakage only a fully finished AM valve revealed promising results. The obtained results could be useful for various enterprises that are seeking weight reduction possibilities for their low-volume manufactured products.

Similarly to corrosion, erosion can have several adverse effects, including human death, environmental pollution, and the loss of assets and productive capacity. The piping and valve systems of oil and gas plants are essential and expensive components that can be subject to erosion depending on factors such as fluid velocity and fluid turbulence. Based on some experience gained in various oil and gas projects primarily on the Norwegian continental shelf, this paper aims to mitigate the effects of erosion on piping and valves. As part of this paper, several strategies and cases are discussed in detail, including the use of hard facing materials for valve internals, the change of globe valves to a more appropriate style of globe valves, the use of straight pipe before and after check valves, the use of bends rather than elbows, and the selection of valves for dirty services near the first stage separator.

Marine discharge structures play a critical role in managing the release of brine disposal, where dilution is essential to minimize environmental impacts. The hydraulic design of the diffuser is a key task in the design of the entire outfall, and a proper design is only possible through the analysis of jet geometry and behavior to ensure sufficient dilution. In this study, round and duckbill nozzle types were modeled to analyze the impact of nozzle geometry on initial dilution. For this purpose, three-dimensional models were created using the computational fluid dynamics (CFD) software Ansys Fluent. Models were analyzed under the same conditions, such as discharge, port area, and receiving ambient density, by changing only the nozzle geometry. Afterward, the effect of the most effective nozzle type, determined as duckbill-type, on the inclined dense jet discharge was also investigated in terms of the optimum jet angle for effective dilution. Then, the same system was solved at two different flow rates and nozzle angles. Models with duckbill nozzles have relatively higher initial dilutions at the centerline peak and the turning points than those with round nozzle geometry. In addition, the duckbill-type nozzle models also showed longer trajectories at various flow rates. The analysis also revealed that the effective angle for using the duckbill check valve is 45°. The findings provide valuable information for the optimization of marine discharges.

One-way surge tanks are commonly employed as water hammer protection devices. However, the action process of the check valve is often disregarded in the design of protective measure. In this study, a one-way surge tank model incorporating a check valve was developed based on the method of characteristics. The check valve action process and different installation positions for one-way surge tanks were investigated based on an actual water supply project. The results show that, compared with the existing one-way surge tank mathematical model, the pipeline pressure calculated by the new model is smaller and the water replenishment is slower, which means that there is a safety risk based on the calculation results of the existing model. As the opening process of the check valve slows down, the pipeline minimum pressure is reduced. When the valve opening rate reaches 0.5 s, negative pressure appears in the pipeline. In addition, for undulated terrain with two obvious high points, when the first one-way surge tank is installed at the node behind the pump, the second one should be installed at the highest point to ensure that the pipeline pressure is greater than 0 m.

Check valves are key components in hydraulic systems. The cross-port leakage in check valves is a common fault that affects their performances. The vibration and pressure fluctuations excited by leaks are weak, therefore leakage is difficult to be identified and classified by intelligent algorithms and non-destructive testing methods. To maximize the performance of leak pattern recognition, we had improved the sequential minimal optimisation algorithm for enhancing the classification performance and tested it with the University of California Irvine Machine Learning Repository. Furthermore, combining with the search and rescue team (SaRT) algorithm, we propose SaRT-SVM algorithm. Two important parameters γ and C of support vector machine (SVM) were optimised and compared with response surface and other algorithms. We analysed the SaRT–SVM method for leakage pattern recognition and validated the robustness of the developed method by applying the method on multiple fault samples of each fault mode, additional different noises, and another independent data collection. The results showed that the SaRT–SVM algorithm exhibited excellent classification performance and robustness when applied to the leakage pattern recognition of hydraulic check valves under the influence of different noises.

Elements of microfluidic systems created by 3D printing offer numerous advantages, such as rapid manufacturing, low cost, and the ability to create complex 3D channel topologies. Their parameters and performance can be quickly adjusted by editing the model loaded into the printer. However, the mechanical properties of polymers used for printing are often poorly documented and can significantly change over time due to aging, relaxation, or creep effects, leading to unexpected behaviour of 3D-printed devices. To address this issue, we performed a complete mechanical characterization of the samples made by 3D printing, including stress relaxation and creep tests, at different time intervals after printing. The determined properties of the material allowed us to model the mechanical and hydrodynamical performance of the 3D-printed microfluidic device, which we demonstrate using an example of a fully printed check valve specially developed for use in microfluidic systems. This approach allows easy quantitative evaluation of the optimal production cycle and lifetime of 3D-printed microfluidic devices.

A passive microvalve has appealing advantages in cost-effective and miniaturized microfluidic applications. In this work, we present a passive flow regulatory device for enhanced flow control in a microfluidic environment. The device was integrated with two functional elements, including a flow regulating valve and a flow check valve. Importantly, the flow regulating valve could maintain a stable flow rate over a threshold liquid pressure, and the flow check valve enabled effective liquid on/off control, thus accurate forward flow without any backward leakage was achieved. The flow performance of the flow regulating valve was analyzed through 3D FSI (Fluid-Structure Interaction) simulation, and several key parameters (i.e., fluidic channel height and width, control channel length, and Young’s modulus) were found to influence valve flow rate directly. To examine the flow characteristics of the device, we fabricated a prototype using 3D printing and UV laser cutting technologies, and the flow rates of the prototype under varied test pressures were measured in forward and reverse modes, respectively. Experimental results showed that nearly a constant flow rate of 0.42 ± 0.02 mL s−1 was achieved in the forward mode at an inlet pressure range of 70 kPa to 130 kPa, and liquid flow was totally stopped in the reverse mode at a maximum pressure of 200 kPa. The proposed microfluidic flow regulatory device could be employed for accurate flow control in low-cost and portable Lab-on-a-Chip (LoC) applications.

Due to the complicated engineering operation of the check valve in a high−pressure diaphragm pump, its vibration signal tends to show non−stationary and non−linear characteristics. These leads to difficulty extracting fault features and, hence, a low accuracy for fault diagnosis. It is difficult to extract fault features accurately and reliably using the traditional MPE method, and the ELM model has a low accuracy rate in fault classification. Multi−scale weighted permutation entropy (MWPE) is based on extracting multi−scale fault features and arrangement pattern features, and due to the combination of extracting a sequence of amplitude features, fault features are significantly enhanced, which overcomes the deficiency of the single−scale permutation entropy characterizing the complexity of vibration signals. It establishes the check valve fault diagnosis model from the twin extreme learning machine (TELM). The TELM fault diagnosis model established, based on MWPE, aims to find a pair of non−parallel classification hyperplanes in the equipment state space to improve the model’s applicability. Experiments show that the proposed method effectively extracts the characteristics of the vibration signal, and the fault diagnosis model effectively identifies the fault state of the check valve with an accuracy rate of 97.222%.

The relationship between impact cavitation characteristics and cavitation damage of a pure water hydraulic control check valve under high pressure and high flow was investigated to prevent cavitation damage. The surface shape, phase, chemical state, and polarization curve of the hydraulic control check valve after pure water impact at high pressure and high flow were analyzed. The results indicate that the greater the impact pressure, the more pronounced the pressure drop at the throttle and the greater and more intense the cavitation range at the flow passage's rear end. Less impact pressure results in a quicker unloading process, and impact pressure has a significant effect on unloading time. With the improvement of impact characteristics, both the cavitation index and cavitation damage intensify. Cavitation collapse can rapidly transfer high temperatures to the surface of stainless steel, resulting in a martensitic structure through the rapid cooling of a pure water medium. After cavitation collapse, the passivation film of the stainless steel surface appears with early cracks and pores, which are more fragile than the surrounding area, resulting in a higher current density in the contained area, resulting in more H + in ionization, thus an acidic corrosive solution, and accelerating the destruction of the passivation film.

Check valves are used extensively in industrial piping systems. Based on dynamic mesh technology, this study uses the RNG k-ε turbulence model to numerically calculate the dual disc check valve’s three-dimensional transient flow. The dynamic characteristics of the check valve in the pipeline system are also experimentally studied. To this end, the two discs are opened synchronously during the valve-opening process, including four stages: opening discs at a constant angular velocity, opening slowing down discs, slowly returning discs to the balance point, and discs maintaining oscillation. However, the movements of the two discs are asynchronous in the valve-closing process. As the downstream pressure increases, the valve disc begins to close, and the flow gradually stops; reverse flow takes shape, and the reverse flow stops until the discs are fully closed, and slamming of the check valve occurs. The non-dimensional dynamic characteristic curve of this type of dual disc check valve has a slope of about 1.624, which mirrors the response of the check valve closing to the occurrence of the water hammer in the system. Knowing the dynamic behavior can be convenient in designing and selecting a check valve and regulating piping system working conditions.