scholarly journals Theoretical Basis of Face Contact Pressure Design of Zero-leakage Mechanical Seal

2021 ◽  
Author(s):  
Wei Zheng ◽  
Jianjun Sun ◽  
Chenbo Ma ◽  
Qiuping Yu
Keyword(s):  
Liquid Medium ◽  
Contact Pressure ◽  
Working Conditions ◽  
Pressure Range ◽  
Working Condition ◽  
Mechanical Seal ◽  
Mechanical Seals ◽  
Medium Temperature ◽  
The Face ◽  
Long Life

Abstract Based on the percolation theory, the critical porosity of zero-leakage at the wetting and non-wetting sealing interface working in liquid medium is first discussed. The influence of end-face frictional heat on end-face friction and wear is then investigated. The design criteria for the face contact pressure of mechanical seals with zero-leakage and long-life operation are established. Afterwards, the face contact pressure range of the mechanical seal working in conventional different liquid medium is calculated, and the influence of different working conditions speed, medium temperature and pressure on the face contact pressure range change is analyzed. Existing studies have shown that mechanical seals can achieve zero-leakage and long-life operation. As for the wettable sealing interface, the minimum face contact pressure, corresponding to the zero-leakage condition, is only related to the morphological parameters of the sealing interface, and has nothing to do with the sealing medium. Under the rotating and stationary rings physical parameters and given working conditions, the face contact pressure range of the sealing medium water and propane propylene is 0.477~1.132 MPa. The diesel sealing medium has a larger face contact pressure range than that of water and propane propylene, which can reach 0.477~2.183 MPa. The working condition speed, medium temperature and medium pressure have an influence on the face contact pressure range, while the influence of the working condition speed is the most significant.

Effect of Spring Pressure on Basic Performance of Contacting Mechanical Seals

2007 ◽  
Vol 353-358 ◽  
pp. 2990-2993
Author(s):  
Jian Jun Sun ◽  
Bo Qin Gu
Keyword(s):  
Fractal Theory ◽  
Operating Conditions ◽  
Mechanical Seal ◽  
Test Results ◽  
Mechanical Seals ◽  
Friction Characteristic ◽  
Basic Performance ◽  
The Face ◽  
Identical Type ◽  
Selection Of

While the fact that abrasion leads to change of surface topography is taken into consideration, the influence of spring pressure both on leakage rate and on friction characteristic of contacting mechanical seals are investigated by fractal theory. Several GY-70 type mechanical seals are tested. Both theoretic analysis and test results indicate that the friction will be more serious because lubrication medium between two end faces reduces as spring pressure increases, though the increase of the spring pressure may not be enough to change the face friction state of mechanical seal. There is an optimum spring pressure for mechanical seal operation. Under different operating conditions, identical type mechanical seals may possess different spring pressure. Appropriate selection of spring pressure is key to the mechanical seal operation under the best condition.

scholarly journals Study on Optimization of Operating Parameters of Contact Mechanical Seal Based on Orthogonal Test

2021 ◽  
Vol 2137 (1) ◽  
pp. 012043
Author(s):  
LuLing Dai
Keyword(s):  
Power Consumption ◽  
Working Condition ◽  
Great Influence ◽  
Orthogonal Experimental Design ◽  
Mechanical Seal ◽  
Mechanical Seals ◽  
Motor Speed ◽  
Specific Pressure ◽  
Friction Power ◽  
Contact Mechanical

Abstract The working condition parameters of common contact mechanical seals are experimentally studied by orthogonal experimental design. The effects of working condition parameters on mechanical seal performance are compared by variance and range analysis, and the optimal sealing working condition is put forward. The results show that the spring specific pressure has a great influence on the leakage of mechanical seal, and the leakage decreases rapidly with the increase of spring specific pressure; With the increase of spring specific pressure, the friction power consumption increases. According to the test results, considering the requirements of mechanical seal performance and service life, the optimal spring specific pressure is 0.028 MPa under the condition of medium pressure ps =0.60 MPa and motor speed n =2960 r/min. At this time, the leakage is 6.120 ml/h and the friction power consumption is 0.648 kW.

scholarly journals Research on Sealing Properties and its Influence Factors of Spherical Mechanical Seal Based on ANSYS

2016 ◽  
Vol 10 (1) ◽  
pp. 160-172
Author(s):  
Xuhui Zhou ◽  
Zhenglin Liu ◽  
Li Zou ◽  
Xingxin Liang ◽  
Huanjie Wang ◽  
...  
Keyword(s):  
Contact Pressure ◽  
Thermal Structure ◽  
Contact Region ◽  
Engineering Application ◽  
Underwater Vehicles ◽  
Outer Diameter ◽  
Mechanical Seal ◽  
Mechanical Seals ◽  
Study Results ◽  
Maximum Contact

When a marine stern shaft is bent with shafting misalignment and stern bearing wear factors, etc., the sealing properties of a plane mechanical seal is declined with the increase of both contact pressure and temperature of sealing surface, so a spherical mechanical seal which can automatically adjust the contact state of sealing surfaces is proposed to replace the plane mechanical seal in order to solve the aforementioned problems. The sealing properties of a spherical mechanical seal is directly influenced by the sealing structure size such as sealing spherical radius, the distance between stator and rotary ring seats, inner and outer diameters of stator ring. The thermal-structure coupling model of the spherical mechanical seal in underwater vehicles is built with ANSYS finite element method, and the influence of structure size on the sealing performances of the spherical mechanical seal is discussed. The study results show that as spherical radius is increased, the contact region of spherical sealing surfaces is decreased and the opening region is expanded, and the highest temperature and maximum contact pressure on the spherical sealing surfaces are raised. As inner or outer diameter of stator ring is increased, the maximum contact pressure of the former is raised, and one of the latter is declined, but the highest temperatures of both on sealing surfaces are enhanced linearly. When the distance between static and rotary ring seats is increased, the highest temperature of sealing surface and maximum contact pressure are increased in a nonlinear way. These conclusions are of important theoretical significance and engineering application value for the structure optimization of spherical mechanical seals in vessels, particularly underwater vehicles.

BP-AdaBoost Algorithm Based on Variational Mode Decomposition Optimized by Envelope Entropy for Diagnosing the Working Conditions of a Slideway Seedling-Picking Mechanism

2021 ◽  
Vol 37 (4) ◽  
pp. 665-675
Author(s):  
Zhitao He ◽  
Haiyang Zhang ◽  
Jun Wang ◽  
Xin Jin ◽  
Song Gao ◽  
...  
Keyword(s):  
Empirical Mode Decomposition ◽  
Working Conditions ◽  
Working Condition ◽  
Recognition Accuracy ◽  
Variational Mode Decomposition ◽  
Adaboost Algorithm ◽  
Layer Number ◽  
Entropy Minimization ◽  
Mode Decomposition ◽  
Penalty Factor

Highlights A method of monitoring the working conditions of a slideway seedling-picking mechanism based on variational mode decomposition (VMD), envelope entropy, and energy entropy is proposed. Based on the criterion of envelope entropy minimization, the combination of the decomposition layer number and penalty factor in VMD is optimized to yield a satisfactory decomposition effect of the analyzed vibration signal. The BP-AdaBoost algorithm is used to improve the working condition classification performance for the slideway seedling-picking mechanism. The working-condition identification effect with the proposed method are compared with those through EMD-based, LMD-based, and EEMD-based methods. Abstract . The slideway seedling-picking mechanism is a type of rotating machinery. This study proposes a novel method of identifying the working conditions of slideway seedling-picking mechanisms for early fault diagnosis by utilizing a back-propagation adaptive boosting (BP-AdaBoost) algorithm based on variational mode decomposition (VMD) optimized by the envelope entropy. The experimental results demonstrate that the proposed method can effectively verify the four working conditions (normal state, slideway failure, cam failure, and spring failure). The overall recognition accuracy reaches 90.0% under the optimal combination of the decomposition layer number K and penalty factor a in VMD determined through the envelope entropy minimization criterion. Classification comparisons with empirical mode decomposition (EMD), local mean decomposition (LMD) and ensemble empirical mode decomposition (EEMD) integrated into the BP-AdaBoost algorithm indicate that the overall recognition accuracy of the proposed method is 18.1%, 16.9%, and 15.6% higher than the accuracies of the three conventional methods, respectively. Compared with the K-means, support vector machine (SVM) algorithms, BP-AdaBoost algorithm demonstrates a more dependable capability for identifying the working conditions. This study provides a useful reference for monitoring the working conditions of slideway seedling-picking mechanisms. Keywords: BP-AdaBoost algorithm, Energy entropy, Envelope entropy, Slideway seedling-picking mechanism, Variational mode decomposition, Working conditions.

scholarly journals In Vitro Evaluation of Facial Pressure and Air Leak with a Newly Designed Cushion for Non-Invasive Ventilation Masks

Healthcare ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 523
Author(s):  
Hui-Ling Lin ◽  
Yu-Chi Lee ◽  
Ssu-Hui Wang ◽  
Li-Ying Chiang ◽  
Jui-Fang Liu
Keyword(s):  
Contact Pressure ◽  
Positive Airway Pressure ◽  
Pressure Sensors ◽  
Air Leakage ◽  
Air Leak ◽  
Non Invasive ◽  
Bilevel Positive Airway Pressure ◽  
Non Invasive Ventilation ◽  
The Face

Background: The aim of this study was to evaluate the effect of a newly designed foam cushion on the air leakage and pressure when applied to the face. Methods: A teaching manikin connected to a bilevel positive airway pressure ventilator attached to four different brands of oronasal masks (Amara, Mirage, Forma, and Wizard) was used. The foam cushions of 5-mm and 10-mm-thickness were attached to the masks, and each mask was tested without a cushion. Six pressure sensors were placed on the manikin’s face, and data were recorded. Inspiratory volume and air leak flow from the ventilator were observed. Results: Air leakage was influenced by both the mask brand and the presence of a cushion. The presence of a cushion did not affect the Wizard mask in terms of leakage (p = 0.317) or inspiratory volume (p = 0.726). The Wizard and Amara masks generated the lowest contact pressure on the frontal forehead (p < 0.001) compared to the other five points. Conclusions: Utilisation of a cushion reduces air leakage and maintains greater inspiratory volume regardless of its thickness. The contact pressure varies depending on the brand of the mask, which would require a difference in the thickness of the cushion for pressure reduction.

Research on Feature Extraction Method Based on Rub-Impact Acoustic Emission Signals of Mechanical Seal End Faces

2010 ◽  
Vol 36 ◽  
pp. 68-74
Author(s):  
Chuan Jun Liao ◽  
Shuang Fu Suo ◽  
Wei Feng Huang
Keyword(s):  
Acoustic Emission ◽  
Feature Extraction ◽  
Extraction Methods ◽  
Mechanical Seal ◽  
Mechanical Seals ◽  
Feature Extraction Method ◽  
Different Types ◽  
Ae Signal ◽  
Feature Information ◽  
Ae Signals

Acoustic emission (AE) techniques are put forward to monitor rub-impacts between rotating rings and stationary rings of mechanical seals by this paper. By analyzing feature extraction methods of the typical rub-impact AE signal, the method combining of wavelet scalogram and power spectrum is found useful, and can used to attribute the feature information implicated in rub-impact AE signals of mechanical seal end faces. Both simulations and experimental research prove that the method is effective, and are used successfully to identify the typical features of different types of rub-impacts of mechanical seal end faces.

scholarly journals REFLECTION ON THE WORKING CONDITIONS OF NURSING PROFESSIONALS IN THE FACE OF THE COVID-19 PANDEMIC

2020 ◽  
Vol 6 ◽  
Author(s):  
Vanessa Augusto Bardaquim ◽  
Sérgio Valverde Marques dos Santos ◽  
Ernandes Gonçalves Dias ◽  
Luiz Almeida da Silva ◽  
Rita de Cássia De Marchi Barcellos Dalri ◽  
...  
Keyword(s):  
Working Conditions ◽  
The Face ◽  
Nursing Professionals

Introducão: A Organização Mundial da Saúde (OMS) foi notificada da presença de um novo vírus, altamente contagioso, pela China em 2019. Em 2020 a OMS declarou emergência de Saúde Pública e uma nova pandemia. A cepa desse novo vírus tornou-se conhecida como coronavírus 2, Síndrome Respiratória Aguda Grave Coronavírus 2 (SARS-CoV-2) e também como COVID-19. Delineamento: Este artigo é uma análise teórico-reflexiva, descritiva, narrativa elaborada a partir de duas categorias norteadoras da reflexão sobre as condições de trabalho e saúde dos profissionais de enfermagem no enfrentamento da COVID-19 no Brasil. Resultados: duas categorias foram formadas “o novo coronavírus e a COVID-19: cenário e desafios postos” e “as condições de trabalho e a saúde dos profissionais de enfermagem no enfrentamento da COVID-19”.  Implicacões: Compreendeu-se que a pandemia da COVID-19 é capaz de gerar muitas incertezas no ambiente profissional, em especial quanto à transmissibilidade das partículas virais infectantes e a proteção do profissional, dessa maneira faz-se necessária atenção especial aos trabalhadores da enfermagem que estão expostos no cuidado de pacientes infectados, às vezes submetidos a condições de trabalho insalubres. Recomenda-se aos gestores intensificar esforços para garantir que esses trabalhadores tenham garantidas as condições necessárias para exercer suas atividades de forma segura.

scholarly journals Piracy as Labour Struggle

2016 ◽  
Vol 14 (1) ◽  
Author(s):  
Gavin Mueller
Keyword(s):  
Intellectual Property ◽  
Working Conditions ◽  
Labor Process ◽  
Bulletin Board ◽  
Digital Piracy ◽  
Electronic Bulletin Board ◽  
The Face

This paper examines the organization of digital piracy in the context of reshaping labor under neoliberalism. It discusses the practices by which enclosures of intellectual property are resisted by drawing from literature on the labor process, and examining the historical emergence of piratical practice on electronic bulletin board systems. These pirates sought, above all, to preserve autonomous, self-managed working conditions in the face of tendencies to commodify, enclose, and deskill.

SPECIFICITY OF HOTEL SERVICE PERSONNEL MANAGEMENT

2020 ◽  
Vol 10 (10) ◽  
pp. 2522-2531
Author(s):  
A.K. Samadova ◽  
Keyword(s):  
Working Conditions ◽  
Stress Resistance ◽  
Staff Training ◽  
Personnel Selection ◽  
Main Task ◽  
Modern Methods ◽  
Hotel Service ◽  
The Face ◽  
Fierce Competition ◽  
Personnel Department

This article examines the effectiveness of management and quality improvement due to the various tools considered in the article; it gives recommendations for improving the efficiency of staff, training it for a new level and improve its qualifications and the efficiency of the hotel. In the face of fierce competition, hotel companies come up with and carry out new searches for modern methods of increasing competitiveness between hotel companies and creating demand for hotel services. One of the ways to make a hotel competitive is to enhance the hotel services in the enterprise. Hotel services directly depend on the competence of the staff, on their preparedness and stress resistance. In turn, the hotel company must contain satisfied employees to service hotel guests. Basically, the HR department monitors the number of personnel, their main task is to have as many employees in the company as should be in the staffing table. But now today it is important for the personnel department to achieve not only the timely filling of personnel, but to hire competent employees with good knowledge and qualifications. It is necessary to retain a good worker by offering and developing good working conditions, a system of motivation and quality management. As a result, an agreed personnel policy will be developed, which includes a system of personnel selection, training, improvement, personnel remuneration, as well as an established policy and subordination between management and subordinates. This article examines how, by applying different methods, to build good relationships between employees, to increase the motivation system, and to be a competitive hotel.

Grassroots struggles to protect occupational and environmental health

2019 ◽  
pp. 189-210
Author(s):  
Kathy Jenkins ◽  
Sara Marsden
Keyword(s):  
Occupational Health ◽  
Environmental Justice ◽  
Environmental Health ◽  
Working Conditions ◽  
Union Membership ◽  
Migrant Workers ◽  
Trade Unions ◽  
Downward Pressure ◽  
The Face ◽  
Changing Patterns

This chapter is based on a number of international case studies of grassroots occupational and environmental health struggles that are attempting to link workplace, environment and community. Interviews with key people involved in each struggle, in combination with documented campaigns and our own experience as occupational and environmental health activists, have provided a picture of the changing patterns of work under neoliberalism, and the implications for community and workers’ struggle for environmental justice and occupational health. Themes include the erosion of the distinction between work and community and between the workplace and the environment; the increasing casualisation and precarity of work; downward pressure on working conditions; repression of trade unions and decline in union membership; deregulation of work, safety and environmental protection; and particular risks faced by women, young and migrant workers. Union and community organisers are employing diverse tactics in the face of these challenges.

Sign in / Sign up

Export Citation Format

Share Document