On the market situation and development of China drainage valve

    Infrastructure construction is the focus of China's economic construction, water supply and drainage, sewage treatment works, the vast scale, including piping, valves, water treatment equipment manufacturing industry has formed a strong water industry. Provides a good opportunity for the development of the valve industry. China has entered the WTO, the global annual demand valve about 300 million tons. To take full advantage of the valve industry is labor-intensive, poor working conditions, low wages of China's per capita transfer of production from developed to developing countries and other advantages, actively toward the platform of the world economy. Several topics briefly to the the drainage valve status quo and development.

    The current status

    Now there are about 3000 Size Valve Factory, 600 including Wenzhou, Zhengzhou, nearly 200 more than more than 150, Shanghai, Liaoning 250, Jiangsu, Fujian, more than 200, despite the good and the bad, but the product varieties has reached more than 3,000 models nearly 30,000 specifications. In many varieties, sealing performance, strength requirements, the regulatory function, action, performance, and circulation performance, especially the sealing performance, has made great strides backwards ten years ago, the authorities of the Urban Water Supply Association a sentence industry famously said "ten valve nine-drain ", although exaggerated, but it is a fact.

    Many problems caused by the existence of the valve industry after the reform and opening up, the market is expanding rapidly, and the original state-owned enterprises have Guantingbingzhuan valve Originally mechanical industrial level is not high, so the township and village enterprises (private enterprise), developed rapidly mushrooming low starting point, the technical force is very weak, poorly equipped, imitation products are mostly production, coupled with the confusion in the market, especially the low pressure valves used in water supply and drainage, a serious problem. Over the past decade, a small number of the valve business driven, there are obvious progress, Hongfeng concluded Some varieties even reached the international advanced level, there are many businesses a secondary business. But on the whole, the gap is still very great, a lot of work to do. To this end, respectively, made in 2010, 2020, technological progress, the development plan has a very important significance.

    Common valve

    Water supply and drainage projects, in low pressure valves widely used, particularly in the low-pressure large diameter valves (low pressure valve is the valve of the nominal pressure PN ≤ 1.6MPa), while the less pressure valve (PN2.5-6.4MPa). Valve, butterfly valve leading product is the most fundamental and widely used.

    2.1 gate valve status quo and development

    Gate valve using the oldest and the countries of the world is still so far applications, especially DN300mm, still dominated by various types of valves. Wherein the force pressure on a valve seat on the right side of the outlet, sealing preferably the pressure difference before and after the valve plate to the valve plate, and when fully open, since the valve plate does not remain in the flow path, the pressure loss is small. Used to cut off the pipeline medium.

    The disadvantage is that the operating torque, easy to make when operating the valve body, stem damage, especially large diameter valve. Dimensions and weight DN1000 diameter valve approximately 3200mm high, you need four people to operate, so the gate valve is generally used in small-caliber DN500 below.
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    The gate valve from the open to the intermediate opening degree, the smaller the flow resistance of the valve near the fully closed state, the flow resistance is increased dramatically. The large range, the small changes in flow resistance, close to the fully closed, the flow rate change is large, must not be used when the valve close to the closed, then difficult for the fine tuning of traffic. Valve if the degree of opening minimum, the flow rate of the opening of fast, causes the shutter lower side to produce cavitation, and accompanied by intense vibration and noise, throttling operation for a long time, often make the metal of the valve body and the shutter cavitation. Gate valve condition in the intermediate degree of opening, the valve plate by the both sides of the rail support, when fully closed closely, while the intermediate position, the valve plate with a large guide clearance generated vibrations. Hongfeng that, even in a low incidence of the cavitation region, for a long time so that the valve to throttle operation, the rails will be deformity occurs, wear or damage, and since the valve seat is not fully contact the surface pressure is high, while the contact portion, often have a bite eclipse or adhesions, therefore, should not be used for flow control.