Water conservancy valve selection
The valve is a kind of control device that "raises soldiers for a thousand days and is used for a while". Usually the valve opening is required to be in place to reduce the water loss of the pipe section: once needed, the valve should be able to close quickly and reliably cut off the flow.
The principle of valve selection in the water supply system is to ➽ choose high-quality, reliable and applicable valves. For types that have not been able to meet the requirements for a long time, new, more advanced valves should be considered.
Next
, to give you a description of the application of several commonly used valves in the water supply system as an example.
1. Globe valve selection
introduce
As the most used valve in the pipe network, the shut-off valve is often used in the DN<50mm water supply network.
Chin-hsien
For a long time, the globe valve used in the pipe network system has the common phenomenon of "leakage, loose closing, and short life".
Technical measurements
The selection of globe valves should be measured from the following technical aspects, and then determined:
(1) The minimum size of the water cross-section
(2) Valve cavity flow type. Depending on the need, choose the straight-through or angular cut-off type
(3) The size of the valve stem, the wall thickness of the valve body and the material of each part of the valve
(4) Upper seal form. Whenever possible, use a "0" type seal and a shut-off valve with high quality packing
(5) Anti-corrosion performance. There is no rust or corrosion inside and outside the valve, especially the parts in contact with water are clean and hygienic
prompt
In the selection of water conservancy engineering valves, select products according to the above requirements to control the quality and performance of globe valves.
2. Selection of gate valves
introduce
In 100 mm< DN < 600 mm water supply networks, conventional hard-seated gate valves (Z41T-1.0) are often used
Chin-hsien
This kind of gate valve has defects such as "loose closing, leakage, and ineffective opening and closing", and the maintenance is particularly frequent.
Features of soft seal gate valves
A kind of soft seal gate valve (also known as "elastic seat seal gate valve") that appears in large quantities on the market today can basically avoid these problems.
This soft-seated gate valve has the following features:
(1) There is no groove at the bottom, so it will not cause the failure of loose closing;
(2) The valve plate is coated with rubber as a whole, and the elasticity of rubber is used to improve the sealing performance of the valve and ensure zero leakage;
(3) The upper sealing structure is more reasonable, the manufacturing precision is high, and the multi-channel "O" type rubber ring seal is adopted, which fundamentally solves the phenomenon that the gland on the traditional gate valve is easy to leak, and also has a fundamental guarantee for water quality.
3. Selection of butterfly valves
Chin-hsien
The use of butterfly valves in the pipe network has the phenomenon of "loose closure, unreliable work, and frequent maintenance": and its service life is short, and some need to be replaced as a whole after 3~5 years of use. However, butterfly valves are cheaper than gate valves of the same specification.
Several issues to be concerned about the selection of butterfly valves:
1. Midline butterfly valve
The centerline butterfly valve is used in a large amount of small-caliber butterfly valves in the mainland, and the effect is relatively good.
2. Vertical and horizontal butterfly valves
In medium and large butterfly valves, there is a difference between vertical and horizontal valve shafts, usually the vertical butterfly valve is covered with deep soil, and the debris in the water is easy to wrap around the shaft end, affecting the opening and closing: the variable speed gearbox of the horizontal butterfly valve is next to the side, and the valve well occupies a wide plane position on the road, which affects the arrangement of other pipelines. Therefore, the vertical type is mostly used in the medium-sized medium-diameter butterfly valve, and the large-diameter butterfly valve strives to be horizontal under the condition that the flat blood position is permitted.
3. Eccentric butterfly valve
The opening and closing torque of the midline butterfly valve is large, and the daily service life is short. In order to alleviate the shortcomings in this regard, an eccentric butterfly valve is selected. The eccentric butterfly valve is directional in carrying water pressure, and the reverse pressure bearing capacity is weak, so this requirement should be emphasized when selecting and ordering.
4. Soft seal and metal seal
prompt
When selecting a butterfly valve, we should consider the following factors
A. Butterfly valve sealing surface rubber ring material, fixing method
B. The size, accuracy and material of important parts
C. Operating environment of butterfly valve
D. Price Factor
Among them, special attention should be paid to the material of the sealing surface and the fixing method.
4. Selection of check valve
Brief introduction
Check valves play a role in making the medium flow in one direction in the water supply system.
Selection considerations
When selecting the valve body, the first thing to consider is the flow area of the valve body, the form of the sealing surface and the valve body material. Secondly, it is necessary to consider the structural form of the check valve, in this regard, everyone's selection work is prone to problems.
Here, I would like to remind ➽
1. Swing check valve can be applied on both horizontal and vertical pipelines
2. The lifting check valve can only be used on horizontal pipelines
Comparison of water conservancy valve selection
Next, through comparison, the selection and comparison of common valves in water supply systems of water conservancy projects are introduced.
Gate valves and butterfly valves
Ball valves, plug valves and butterfly valves
The ball valve has the advantages of simple structure, small flow resistance, reliable sealing, flexible action, convenient maintenance and operation.
The plug valve has similar advantages, except that the water crossing area is not perfectly circular. Ball valves and plug valves are heavier than butterfly valves, difficult to cast and process, and more expensive, generally suitable for small and medium-sized pipes. In recent years, due to the improvement of casting technology, the production cost of ball valves has been reduced. Therefore, the feasibility of ball valves for large-diameter pipelines is worth exploring.
The industry demand for water conservancy valves in China
The current situation in the country
Judging from the current situation in China, infrastructure construction is the focus of the mainland's economic construction, and changes in the construction of water conservancy projects are becoming more and more important. This has increased a lot of opportunities for manufacturers of hydraulic engineering valves, and at the same time, the competition between enterprises has gradually increased.
In recent years, the state has increased investment in infrastructure construction, and the water treatment equipment manufacturing industry, including hydraulic control valves and other valves, has formed a strong industrial chain, which provides a huge space for the development of the hydraulic control valve industry. The water conservancy valve manufacturing industry belongs to mechanical engineering manufacturing, and with the increasing demand for check valves, control valves and environmental protection valves in developing countries, it is expected that there is still a lot of room for improvement in this industry in the future. According to the statistics of China Machinery Industry Association, the total global demand for various types of valves, including industrial valves, is about 60 billion US dollars, of which the hydraulic control valve is about 6.84 billion US dollars.
Trends
With the increasing urbanization rate and the rapid growth of urban population in mainland China, the water supply of water plants and the scale of sewage treatment in sewage treatment plants are gradually increasing, and the diameter of the pipe network is increasing, so a large number of large-diameter and super-large diameter water supply and drainage valves are needed.
At the same time, the construction of various flood control, drainage, irrigation, water supply and drainage, hydroelectric power generation, soil and water conservation, water resources protection and other projects included in the management of water conservancy infrastructure has a very strong demand for various large-caliber and super-large caliber water supply and drainage valves, resulting in the current domestic large-caliber and super-large caliber water supply and drainage valve production capacity and output can not meet the growth of downstream market demand.
In the next few years, the mainland will continue to speed up the implementation of the three new projects for the control of the Huai River and the comprehensive treatment of Taihu Lake, Dongting Lake and Poyang Lake, promote the management of key sections of major rivers such as the Ningmeng section of the Yellow River and the river potential control in the middle and lower reaches of the Yangtze River, and the development of the "South-to-North Water Diversion" century project, which will continue to stimulate the demand for various valve products, especially large-caliber gate valves, large-caliber turbine inlet butterfly valves, extra-large-caliber hydro turbine inlet ball valves, extra-large-caliber flow control valves and extra-large-caliber vacuum valves. Because the technical and technological requirements for the production of large-diameter and super-large diameter valves are much higher than those of ordinary valves, the added value of a single product is higher, which puts forward higher requirements for product design level and processing level.
At present, there are not many enterprises in China that can meet the requirements of technical equipment, and most of the other enterprises in the industry are mainly engaged in the production of ordinary caliber valves. From the perspective of the entire industry, the production capacity and output of large-diameter water conservancy control valves will show a steady growth trend.
If you liked this article, remember to send it to a good friend!
Share wisdom and good luck!
"Disclaimer: This article comes from the Internet and is not an original article on the hotel engineering exchange platform. The reprinted content is only for learning and exchange, the stated views do not represent the position of the hotel engineering exchange platform, the copyright belongs to the original creator, if there is any infringement, please contact us to delete, thank you'