The Design Research Of Preventing Water Hammer Compound Air Valve

In recent years,more and more trans-regional and long-distance water transfer projects have been carried out,for example the South-to-North Water Diversion Project.Water hammer problems are the most commonly encountered problems during long-distance water transports,and the accidents caused by bridging the water hammer have a very detrimental effect on the pipeline,ranging from damage to pipeline equipment(valves,etc.).Even the pipe burst to catastrophic accident.So it becomes more and more important how to effectively protect the bridging water hammer.The article gives a brief about the phenomenon,cause,damage and classification of water hammer,analyzes in detail how the bridging water hammer is formed in the pipeline,and point out the best standards and the main principles of water hammer protection.The air valve is widely used to protect the water hammer in the long distance water pipeline.The paper discusses the function and structure of the traditional air valve in the pipeline,analyzes the structure of the water hammer composite air valve,compared air valve with water hammer composite air valve,and the analysis conclusion is that the waterproof hammer compound air valve is superior to the traditional air valve for protecting the bridging water hammer.It is more ideal and effective.The design thought of this paper refers to the national standard CJ / T 217-2013 "Compound quick air inbreathe-release valve for water supply pipeline",and proposes that the design of the water hammer proof compound air valve should satisfy four basic elements:(1)the sealing pressure meet the standard;(2)the strength and rigidity of the main parts of the valve need to conforms to the requirement;(3)the displacement of the valve should be able to comply with the standard requirements;(4)the valve function should be able to fulfill the design requirements.According to the valve design parameters,the minimum thickness calculation and other basic data,these four basic elements are expound by the relevant calculations,finite element analysis,displacement analysis and the actual operation of the functional analysis.Finally,it is concluded that the water hammer proof compound air valve meets the standard and is able to conform to the design requirements.The air valve can be put into practical production,which can effectively avoid the water hammer,and is worth popularizing.The designed air valve of this paper is a new type of water hammer proof compound air valve.The air valve has more advantages to protect the bridging water hammer,more complicated than the general water hammer,for the traditional air valve: firstly,it has the traditional air valve Of the full function,for example exhaust and air intake;secondly,it has the innovative design in the structure,which added a buffer device on the large exhaust port.It can rapidly exhaust and inlet,slowly discharge the gas in the pipeline to bridge the slug flow,through the small mouth,and it effectively blocked the slug flow closure.The results show that this study of the new water hammer proof compound air valve can solve the problem of bridging water hammer.