• Title/Summary/Keyword: hammer

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Experimental Study on the Water Hammer Absorption Effects of Water Hammer Arrester in the Water Supply Piping System (급수관로계에 설치된 수격흡수기의 수격흡수효과에 관한 실험적 연구)

  • Choi, Jung-Geun;Lee, Suk-Jong;Lee, Myoeng-Ho;Sung, Jae-Yong
    • Journal of Advanced Marine Engineering and Technology
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    • v.30 no.3
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    • pp.396-402
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    • 2006
  • In this study, dynamic characteristics of water hammer pressure in water supply piping system with water hammer arrester has been investigated experimentally to characterize the transient pressure of water hammer in high rise building. Experiments were conducted to verify the absorption effects by water hammer arresters with 3 different gas volumes of water hammer pressure generated by sudden valve closure. As the results, it has been found that zoning and sizing of pipe diameter for suitable flow velocity and water hammer arresters with effective pressure absorption capacity have to be installed to protect water hammer problems in building water supply piping system.

A Study on Hammer Performance Evaluation (항타장비의 성능평가 연구)

  • 홍헌성;이명환;조천환;김성회;전영석
    • Proceedings of the Korean Geotechical Society Conference
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    • 2002.03a
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    • pp.405-412
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    • 2002
  • The performance of a hammer/driving systems is a major factor which affects bearing capacity and integrity of installed piles. Hammer performance can be evaluated from the results of dynamic pile testing using Pile Driving Analyzer(PDA). By comparing the rated energy with measured maximum transferred energy(EMX), the energy transfer ratio(ETR) can be calculated. This paper based on the dynamic measurements of 442 cases in 130 piling projects and evaluated ETR according to the hammer types(hydraulic and drop hammers) and pile types(steel and concrete piles).

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Hammer Energy Level of SPT in Korea (표준관입시험의 해머에너지 수준)

  • 이호준;박용원
    • Geotechnical Engineering
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    • v.12 no.5
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    • pp.117-126
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    • 1996
  • In spite of many advantages such as the simplicity in test procedure, Standard Penetration Test(SPT) results contain some errors caused by the variability of test equipment, instruments and test procedures. Especially, it is inevitable that the measured SPT hammer energy is different from the theoretical value because of energy loss. In this paper, the hammer energy level is measured during the performance of the field SPT in Korea by using a ultra-sonic system and PC.program. As the results of this study, the average hammer energy ratio of the R-P hammer and the Trip hammer is calculated at 64.2%, and at 75.0% respectively. The average energy ratio of the SPT for the R-P hammer is calculated at 46% and at 54% for the Trip hammer, by applying the rod energy ratio 0.72.

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Effects of the Lift Valve Opening Area on Water Hammer Pump Performance and Flow Behavior in the Valve Chamber

  • Saito, Sumio;Dejima, Keita;Takahashi, Masaaki;Hijikata, Gaku;Iwamura, Takuya
    • International Journal of Fluid Machinery and Systems
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    • v.5 no.3
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    • pp.109-116
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    • 2012
  • Water hammer pumps can effectively use the water hammer phenomenon for water pumping. They are capable of providing an effective fluid transport method in regions without a well-developed social infrastructure. The results of experiments examining the effect of the geometric form of water hammer pumps by considering their major dimensions have been reported. However, these conventional studies have not fully evaluated pump performance in terms of pump head and flow rate, common measures of pump performance. The authors have focused on the effects on the pump performance of various geometric form factors in water hammer pumps. The previous study examined how the hydrodynamic characteristics was affected by the inner diameter ratio of the drive and lift pipes and the angle of the drive pipe, basic form factors of water hammer pumps. The previous papers also showed that the behavior of water hammer pump operation could be divided into four characteristic phases. The behavior of temporal changes in valve chamber and air chamber pressures according to the air volume in the air chamber located downstream of the lift valve was also clarified in connection with changes in water hammer pump performance. In addition, the effects on water hammer pump performance of the length of the spring attached to the drain valve and the drain pipe angle, form factors around the drain valve, were examined experimentally. This study focuses on the form of the lift valve, a major component of water hammer pumps, and examines the effects of the size of the lift valve opening area on water hammer pump performance. It also clarifies the behavior of flow in the valve chamber during water hammer pump operation.

A Study on the Redistribution of Residual Stress Induced by Hammer Peening after Cast Iron Welding (주철 보수 용접시 Hammer Peening에 의한 잔류응력 재분포에 관한 연구)

  • Park Yun Gi;Kim Gyeong Gyu
    • Proceedings of the KWS Conference
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    • v.43
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    • pp.286-288
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    • 2004
  • The purpose of this study is to evaluate the effects of hammer peening on the redistribution of residual stress at the repair weldment of cast iron using FEA. The FEA results were verified by comparing with experimental results. The maximum residual stress at the repair weldment of cast iron sharply decreases by hammer peening. The effect of hammer peening on the residual stress increases with a decrease of working temperature of hammer peeing.

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Effect of Hammer Material on Crushing of Silica (함마의 재질이 규석의 분쇄에 미치는 영향)

  • Lee, Jae-Jang;Chang, Sang-Geun;Chang, Kwang-Teak;Park, Jong-Ryok
    • Journal of Industrial Technology
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    • v.22 no.A
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    • pp.119-125
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    • 2002
  • In Kwangjin industrial company, mill is operating for the foundry sand production at the rate of 25t/hr from quartzite. Foundry sands fall into four distinct categories: silica sand, lake sand, bank sand, and natural molding sand. Silica sand is a general term used to describe crushed, washed, graded, dried, and cooled clay-free sands. This study was conducted for the investigation of the foundry sand productivity and the life span of the hammer according to the material quality. The life time of hammer from several manufacturer were compared in order to find out the grinding efficiency of the various hammer material. In the result of tests, the life time of high-Mn hammer was 10.5 hours while that of high-Cr was 19.5 hours. The life time in case of typical worn shape hammers was about 12 hours and the average time of a blowhole hammer was about 6.5 hours.

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Performance Evaluation of the Vibro Hammer with Variable Amplitude by Field Tests (현장실험을 통한 저진동·저소음 진폭가변형 진동해머 성능 평가)

  • Han, Jin-Tae;Lee, Joonyong;Choi, Changho;Park, Jeong-Yel
    • Journal of the Korean Geosynthetics Society
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    • v.14 no.3
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    • pp.1-12
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    • 2015
  • During installing sheet piles for an impermeable wall or a retaining wall, vibratory hammers are widely used. Among vibratory hammers, a hydraulic hammer is used most commonly. However, a hydraulic hammer causes excessive vibration and noise due to resonance by change of natural frequency according to movements of eccentric shaft when the hammer starts and stops. In this study, new variable amplitude type hammer is developed in order to reduce the vibration and noise due to resonance produced in starting and stopping the hammer. By controlling horizontal angle in two pairs of eccentric body inside of the hammer, the amplitude and vibration of the new hammer can be controlled. The performance tests with the new hammer and existing hammers such as the hydraulic hammer and electric hammer are carried out, and the new hammer shows reduced vibration and noise results in comparison with existing hammers from performance tests. Also, this study shows that penetration rates of sheet pile using the new hammer increase due to impellent force of a backhoe in comparison with the electric hammer and penetration rate increase in comparison with a general hydraulic hammer, since the new hammer can control the amplitude during penetration of sheet pile according to soil condition.

Performance Optimization of Down-the-Hole Hammer Using Taguchi Method (다구찌 기법을 이용한 Down-the-Hole Hammer의 타격성능 최적화에 관한 연구)

  • Shin, Dae-Young;Song, Chang-Heon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.36 no.1
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    • pp.109-116
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    • 2012
  • There are a number of studies concentrating on drilling equipment and drilling methods, but none investigates the impact performance and optimization of DTH (down-the-hole) drilling. It is very difficult to experimentally evaluate the performance of a DTH hammer, because putting together an experimental setup for DTH drilling requires a great deal of money and time. Therefore, this paper examines the characteristics and performance of DTH hammers through pneumatic simulation after a thorough investigation of their working mechanism. In addition, the parameters linked to the performance of DTH hammers were selected using the design-of-experiment method, and then the optimization of performance factors, which are the impact rate and impact energy, was investigated using Taguchi method.

Effects of the Geometry of Components Attached to the Drain Valve on the Performance of Water Hammer Pumps

  • Saito, Sumio;Takahashi, Masaaki;Nagata, Yoshimi;Dejima, Keita
    • International Journal of Fluid Machinery and Systems
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    • v.4 no.4
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    • pp.367-374
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    • 2011
  • Water hammer pumps can effectively use the water hammer phenomenon in long-distance pipeline networks that include pumps and allow fluid transport without drive sources, such as electric motors. The results of experiments that examined the effect of the geometric form of water hammer pumps by considering their major dimensions have been reported. In addition, a paper has also been published analyzing the water hammer phenomenon numerically by using the characteristic curve method for comparison with experimental results. However, these conventional studies have not fully evaluated the pump performance in terms of pump head and flow rate, common measures indicating the performance of pumps. Therefore, as a first stage for the understanding of water hammer pump performance in comparison with the characteristics of typical turbo pumps, the previous paper experimentally examined how the hydrodynamic characteristics were affected by the inner diameter ratio of the drive and lifting pipes, the form of the air chamber, and the angle of the drive pipe. To understand the behavior of the components attached to the valve chamber and the air chamber that affects the performance of water hammer pumps, the previous study also determined the relationship between the water hammer pump performance and temporal changes in valve chamber and air chamber pressures according to the air chamber capacity. For the geometry of components attached to the drain valve, which is another major component of water hammer pumps, this study experimentally examines how the water hammer pump performance is affected by the length of the spring and the angle of the drain pipe.