scholarly journals Process Characteristics Of Hydraulic Legs Equipped With Safety Valves At Dynamic Load Caused By A Mining Tremor

2015 ◽  
Vol 60 (2) ◽  
pp. 595-612 ◽  
Author(s):  
Andrzej Pytlik
Keyword(s):  
Kinetic Energy ◽  
Dynamic Load ◽  
Safety Valve ◽  
List Type ◽  
Pressure Relief ◽  
Process Characteristics ◽  
Mining Tremors ◽  
Impact Mass ◽  
Additional Safety ◽  
Roof Support

Abstract The article presents process characteristics of hydraulic legs, a powered roof support and an individual roof support that are equipped with pressure relief valves and additional safety valves protecting the legs against dynamic loads caused by mining tremors. A two-telescopic hydraulic leg ϕ330 type was tested using dynamic pile testing, equipped with a valve bank with pressure relief valve and an additional safety valve. The tests included the following models of safety valves described in references (Gwiazda, 1997; Irresberger et al., 2008): – slide-piston with a roller spring, – seat-cone with gas spring, – slide-piston with a roller spring, – two-stage valve (a control valve and a main valve connected in one support). Using pressure charts in time function it is possible to determine how fast the amplitudes of pressure increase with the h height of a ram increase, thereby, Ek kinetic energy of ram’s stroke and p momentum impacting the leg equipped with the valve. Maximum pressure in the leg with the slide-piston valve raised to 64 MPa (with impact mass drop at h = 0.25 m) up to 129 MPa (h = 0.3 m) i.e. by 100%. Pressure increase to pmax = 158 MPa was noted during a test of the slide-piston leg equipped with the valve and with a drop of h = 0.5 m This poses a great hazard that can destroy the valve and therefore cause a loss of load-bearing capacity. Conducted research of SHC hydraulic legs of an individual roof support showed that (Pytlik & Pacześniowski, 2012; Pytlik & Rabsztyn, 2011) quick relief valves had higher efficiency than standard valves mounted in SHC legs, which resulted in lower pressure in the leg by 7 MPa. It has an essential importance for stability of leg’s cylinder and its sealing. The test of the leg with a valve battery was based on its dynamic load impacted by a ram (impact mass) of m1 = 4,000 kg relieved at the leg placed between a cross-bar of m2 = 3,300 kg and post’s foundation. Recording of p pressure of the fluid in its space under piston was made with sampling frequency of 9.6 kHz, Moreover, the research also included test of the same type of SHC leg with BZG-2FS battery (equipped with gas spring) using ram’s mass of m1 = 2,0000 kg and the cross-bass of m2 = 6,600 kg. The leg transferred the load, stroke type, of Ek = 29,5 kJ kinetic energy without any damages. A time-lapse analysis of photos showing the opening moment of the safety valve indicated that its opening had taken place 8 ms after the moment when the leg was impacted and indicated propagation of the hydraulic fluid stream’s front with maximum velocity of about 60 m/s, and maximum momentary intensity of fluid flowing through a bypass valve amounted to Qc max = 683 l/min. The tests of work characteristics of safety valves (Pytlik, 2013, 2014) included valves with M40×2 terminal thread of the following designs: – slide-piston – with three rows of fluid outlets, – slide-piston – with two rows of fluid outlets, – seat-cone – with a single row of fluid outlets. The tests of valves were conducted on the basis of capacity research methodology based on fluid increase of fluid stream caused by mass stroke impacting the leg equipped with the valve, up to twice the working pressure adjusted value of the valve. Such test simulates dynamic load of the hydraulic leg with the valve during mining tremors. Tests results of capacity and valve opening time may be used to determine yielding of an individual powered roof support and to optimize valve construction in order to improve capacity and working time. On the basis of carried out research concerning momentary intensity of Qc flow of safety valves with M40×2 terminal, it may be stated that the valves are characterised by a high level of capacity, presented on charts, and short working time – 3 up to 5 ms. The best technical parameters had a prototype seat-cone valve.

Dynamic Instability Analysis of a Spring-Loaded Pressure Safety Valve Connected to a Pipe by Using CFD Method

2018 ◽  
Author(s):  
Feng Jie Zheng ◽  
Chao Yong Zong ◽  
Fu Zheng Qu ◽  
Wei Sun ◽  
Xue Guan Song
Keyword(s):  
Dynamic Instability ◽  
Safety Valve ◽  
Wave Force ◽  
Design Parameters ◽  
Instability Mechanism ◽  
Pressure Relief ◽  
Pressure System ◽  
System Pressure ◽  
And Performance ◽  
Cfd Method

As the ultimate protection of a pressure system, pressure safety valves (PSV) can respond in an instable manner such as flutter and chatter which will affect service life, reliability and performance. In order to study the dynamic instability caused by multi-source forces including the flow force, the spring compressing force and the pressure wave force, a more realistic CFD model containing a PSV and different connected pipes as well as the pressure vessel is developed, in which advanced techniques in Fluent such as User Defined Function (UDF) and Dynamic Layering method are combined to allow the PSV to operate. Based on this model, the process of the valve’s opening and reclosing is monitored to examine the influence of design parameters on the dynamic instability of the PSV. Specifically, the propagation of pressure waves along the connecting pipes is successfully captured, which is of great help to explain the instability mechanism and optimize the design and setup of pressure relief systems.

scholarly journals Design of an on-line check device for safety valve

2018 ◽  
Vol 232 ◽  
pp. 01045
Author(s):  
Zhipeng Yan ◽  
Qing Li ◽  
Muda Jin ◽  
Haijian Zhong
Keyword(s):  
Hydraulic System ◽  
High Speed ◽  
Safety Valve ◽  
Motor Drive ◽  
Pressure Relief ◽  
Type Safety ◽  
On Line ◽  
Spring Type ◽  
Pulling Force ◽  
Upper Computer

As the main pressure relief component of the tanker, the spring type safety valve is indispensable for its periodic verification. An on-line check device is designed for the check problem of the safety valve. The check device is divided into mechanical structure, program control, motor drive, tension detection, displacement measurement, upper computer, etc., and the safety valve is verified according to the safety valve check principle and the determination method. Compared with the check device that uses the hydraulic system to provide the pulling force, the device has the advantages of simple operation, high speed, convenient disassembly, strong applicability, and the like, and has certain market application prospects.

scholarly journals Analysis of load of a powered roof support’s hydraulic leg

2018 ◽  
Vol 71 ◽  
pp. 00002 ◽  
Author(s):  
Dawid Szurgacz ◽  
Jarosław Brodny
Keyword(s):  
Rock Mass ◽  
Hydraulic System ◽  
Impact Load ◽  
Load Condition ◽  
Dynamic Impact ◽  
Registration System ◽  
Free Falling ◽  
The Impact ◽  
Impact Mass ◽  
Roof Support

The main purpose of the powered roof support is to protect headings from the impact of the rock mass. The result of such impact is static and dynamic load impacting the support section, which is carried by its construction. The basic elements of the construction of the support are hydraulic legs, whose task is to ensure adequate strength of its setting. Particularly in the case of dynamic impact of the rock mass, these legs are exposed to a very unfavourable load condition. Therefore, it is necessary to conduct tests to determine the parameters of operation for this type of loads. The paper presents the results of tests on the hydraulic leg subjected to impact load with free falling impact mass. The purpose of the research was to determine the parameters of the leg's operation, i.e. the time periods of pressure in the space under the piston and other elements of the hydraulic system. The tests were conducted in compliance with designed methodology and included innovative registration system. The obtained results clearly indicate the correctness of the adopted assumptions. According to the authors, the results should be applied during selection and operation of a powered roof support.

ASME Code Safety Valve Rules—A Review and Discussion

1995 ◽  
Vol 117 (2) ◽  
pp. 104-114 ◽  
Author(s):  
M. D. Bernstein ◽  
R. G. Friend
Keyword(s):  
Pressure Vessel ◽  
Safety Valve ◽  
Code Design ◽  
Pressure Relief ◽  
Pressure Tolerance ◽  
Asme Code ◽  
Pressure Relief Valves ◽  
And Function

Safety valve rules, i.e., rules for overpressure protection by the use of various pressure-relieving devices, vary somewhat among the five book sections of the ASME Boiler & Pressure Vessel Code which require such protection. This paper reviews those rules by discussing the following topics: Pressure relief device terminology and function. The problem of overpressure protection. Code rules for overpressure protection: rules for determining required relieving capacity; for allowable overpressure; for set pressure and set pressure tolerance; for blowdown. The various pressure relief devices permitted by the Code. Design of pressure relief valves. How relieving capacities are established and certified. The qualification of pressure relief device manufacturers. Installation guidelines. Concluding remarks.

Improving the safety of resuscitative endovascular balloon occlusion of the aorta – Compliant versus semi-compliant balloon systems

Vascular ◽  
2020 ◽  
Vol 28 (5) ◽  
pp. 612-618
Author(s):  
Marta J Madurska ◽  
Curtis Franklin ◽  
Michael Richmond ◽  
Sakib M Adnan ◽  
Gerard P Stansby ◽  
...  
Keyword(s):  
Safety Valve ◽  
Balloon Catheter ◽  
Balloon Occlusion ◽  
Quadratic Model ◽  
Second Phase ◽  
Relief Valve ◽  
Pressure Relief ◽  
Resuscitative Thoracotomy ◽  
Working Length ◽  
Endovascular Balloon Occlusion

Objectives Resuscitative endovascular balloon occlusion of the aorta is an alternative to resuscitative thoracotomy in non-compressible torso haemorrhage. Low-profile, compliant balloon catheter systems have been developed, which can be deployed without the need for fluoroscopy. However, concern exists for over inflation and aortic injury, especially as compliant balloon material can stretch reducing syringe feedback and limiting the effectiveness of a safety valve. An alternative material would be a semi-compliant balloon material, but its performance is unknown. The aim of this study was to compare the inflation characteristics of compliant versus semi-compliant balloon systems and to determine whether a pressure relief safety valve can be practically applied to a semi-compliant balloon catheter as a safety device. Methods This was an ex vivo study using porcine segments of thoracic aorta. The study consisted of two phases. The first phase involved intermittent inflation of six compliant balloon and six semi-compliant balloon balloons until balloon or aortic rupture. In the second phase, six semi-compliant balloons with the pressure-relief valve set at 0.45 atmospheres were inflated in the aortas until the valve release, followed by injection with additional 30 mL. Data including pressure, volume, balloon working length, diameter and circumferential stretch ratio were collected. Results At failure, mean balloon volume was almost double in compliant balloon group vs semi-compliant balloon group – 49.83 mL (±23.25) and 25.16 mL (±8.93), respectively ( p = 0.004), with 36% increase in working length in the compliant balloon group – 81.17 mm (±19.11) vs 59.49 (±4.86) for semi-compliant balloon ( p = 0.023). When plotted, the relationship pattern between volume and pressure fit a linear model for the compliant balloon, and a quadratic model for the semi-compliant balloon. Following attempted over inflation with the pressure valve, there was no change in parameters before and after attempted over inflation. Conclusions The inflation profile differs between balloon designs. In contrast to semi-compliant balloons, compliant balloons will accommodate more volume to mitigate increase in pressure. This does not completely eliminate the risk of over inflation. The inflation characteristics of the semi-compliant balloon permit pairing it with a safety valve, which could lead to a development of a safer balloon technology in the future.

scholarly journals Dynamic Tests of a Leg in a Powered Roof Support Equipped with an Innovative Hydraulic System

2018 ◽  
Vol 41 ◽  
pp. 03019 ◽  
Author(s):  
Dawid Szurgacz ◽  
Jarosław Brodny
Keyword(s):  
Control System ◽  
Dynamic Load ◽  
Hydraulic System ◽  
Free Fall ◽  
Dynamic Loads ◽  
Hydraulic Control ◽  
Powered Support ◽  
Static And Dynamic Loads ◽  
The Impact ◽  
Roof Support

Static and dynamic loads impact on a powered roof support during its operation. The dynamic loads lead to a number of consequences for the construction and the entire hydraulic system. With the increase of depth and intensity of exploitation, the number of events during which the dynamic load is greater increases. Therefore, it is necessary to research the whole unit of the support and its components under the impact of dynamic load. The article presents the results of tests of a hydraulic leg designed to work in the powered support and dynamically loaded with free fall drop. An innovative hydraulic system type DOH was mounted in the subject leg. As a result of the conducted tests, the dynamic parameters of the tested system were determined. The aim of the research was also to determine the impact of drop’s energy on the operating parameters of the tested system. The tested hydraulic system is a part of an innovative electro hydraulic control system of the powered roof support. The Authors believe that the obtained results will allow to create opportunities for the practical application of the tested system and the entire wireless control system of the mining roof support.

Study on the Safety Integrity of the Pressure Relief Capacity of Pressure Bearing Systems With Relief Characteristics Consideration

2015 ◽  
Author(s):  
Jianxin Zhu ◽  
Xiangrong Fang ◽  
Haizhou Kang ◽  
Lu YunRong ◽  
Chen Xuedong
Keyword(s):  
Safety Valve ◽  
Back Pressure ◽  
Assessment Procedure ◽  
Pipe Network ◽  
Pressure Relief ◽  
Development Method ◽  
Curve Method ◽  
Bearing System

The relief characteristic of safety valve plays an important role on system relief capacity. Based on the analysis of the influence of setting pressure, back pressure, discharger area on relief capacity, a relief curve development method was proposed that takes into account the backpressure based on API 520 standard. The relief curve method is then applied in the analysis of the relief capacity of pressure bearing systems. By taking into consideration the multiple pressure relief characteristics in pipe network, the safety integrity of multiple pressure reliefs was studied and an associated assessment procedure was proposed. The method and corresponding procedure are important contributions for the assessment of safety integrity of relief capacity in pressure bearing system.

scholarly journals Testing the effectiveness of release valves under intensive dynamic load to the leg

2020 ◽  
pp. 466-478
Keyword(s):  
Dynamic Load ◽  
Maximum Pressure ◽  
Load Increment ◽  
Support Unit ◽  
Load Increase ◽  
Yield Test ◽  
The Difference ◽  
Rising Time ◽  
Roof Support

Release valves are commonly used to protect hydraulic legs against overload caused by rock bursts or bumps. Due to an essential role in ensuring safety in the working, an application of a release valve is conditioned by a positive yield test results of a leg equipped with such a valve. A method of leg yield testing, used in Poland, enables a complex determination of an impact of not only a release valve but also of the parameters of the hydraulic leg, determining its stiffness such as for example a volume of the under-the-piston space, which has an impact on an observed pressure increase. The subject of this publication covers cognitive tests oriented onto a determination of an impact of a release valve exclusively on the pressure changes observed in the leg. The results of the efficiency tests of spring valves (Stoiński, 2018) on a rammer are discussed. The difference between the maximum pressure in the under-piston area of the leg with the release valve and the maximum pressure generated by the same dynamic load in the leg without this valve was the measure of the valve operation's effectiveness. Dynamic load, realized on a rammer, is characterized by a longer increase time than in the case of dynamic load acting on a powered roof support unit from the floor. The time process of the force in the leg is then characterized by a short load rising time – tn, large load increment factor – Kd and the average load growth rate –wp,n. Referring to that aspect, the features of a release valve were analyzed in relation to the parameters characterizing dynamic load acting on a powered roof support unit from the floor. Parameters characterizing the effectiveness of the release valve, i.e. change in the leg load increment index –Kd and change in the rate of load increase –wpn were defined. The test stand for generating the load of such parameters using the explosive method is described. Comparison of effects of the dynamic load generated by firing the same mass and the same type of explosive on a hydraulic leg with a release valve and the leg without this valve was the test objective. The effectiveness of the spring valve and two gas valves are analyzed. It was found that despite a very short load rising time, the release valve reduces the load acting on the leg. The positive values of the Kd and wp,n indices are the evidence.

scholarly journals A new pressure relief (safety) valve.

Anaesthesia ◽  
1970 ◽  
Vol 25 (3) ◽  
pp. 411-417
Author(s):  
E. Carden
Keyword(s):  
Safety Valve ◽  
Pressure Relief

Analysis of Droplet Characteristics and Kinetic Energy Distribution for Fixed Spray Plate Sprinkler at Low Working Pressure

2021 ◽  
Vol 64 (2) ◽  
pp. 447-460
Author(s):  
Rui Chen ◽  
Hong Li ◽  
Jian Wang ◽  
Xin Guo
Keyword(s):  
Kinetic Energy ◽  
Energy Distribution ◽  
Water Depth ◽  
Droplet Diameter ◽  
Sprinkler Irrigation ◽  
Infiltration Rate ◽  
Kinetic Energy Distribution ◽  
Specific Power ◽  
List Type ◽  
Working Pressure

HighlightsAn experiment was conducted to investigate the hydraulic performance of a fixed spray plate sprinkler (FSPS).A model was developed for estimating the cumulative kinetic energy of the FSPS under a moving system.The droplet characteristics and kinetic energy distribution were affected by the working pressure and FSPS structure.A high cumulative kinetic energy could lead to a low water infiltration rate into the soil.Abstract. The kinetic energy of droplets from a fixed spray plate sprinkler (FSPS) has a substantial influence on runoff and soil erosion, as well as on the energy consumption of moving sprinkler irrigation systems. To determine the droplet characteristics and kinetic energy of an FSPS, an experiment was conducted to investigate the effects of working pressure, plate structure, and nozzle size on the droplet diameter, velocity, and kinetic energy. Two plates (the FSPSB with a concave trajectory and deep grooves in the blue plate, and the FSPSY with a flat trajectory and shallow grooves in the yellow plate) were used in the tests. The cumulative kinetic energy and water depth were calculated for a single sprinkler moving in a straight line. The results show that the FSPSB, which had deeper grooves in the plate, produced a larger droplet diameter than the FSPSY, with shallow grooves in the plate. The droplet landing velocities presented a logarithmic relationship with the droplet diameter, and velocities increased with an increase in droplet diameter. The peak specific power (SP) value of the FSPSB was 1.14 to 16.76 times that of the FSPSY. When the working pressure was less than 150 kPa, the peak SP of the FSPSB remained at a high level. With an increase in working pressure, the peak SP of the FSPSB initially increased and then decreased, while the peak SP of the FSPSY increased. The cumulative kinetic energy of the FSPSB was higher than that of the FSPSY under mobile spray conditions. Compared with the cumulative water depth, the cumulative kinetic energy of the FSPSB increased and then decreased as the working pressure increased for the same applied water volume. Because the soil had a lower infiltration rate under the FSPSB, surface ponding was more likely to occur with the FSPSB than with the FSPSY at low working pressure. Keywords: Cumulative kinetic energy, Droplet size, Specific power, Sprinkler irrigation, Working condition.

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