Or into a high-tech investment in the direction of valve

With the continuous development of science and technology, the domestic valve market, but also to the high-tech, high-parameter, strong corrosion-resistant, high-life direction. Valves based on technical analysis at home and abroad and domestic market demand valve and analyzed in recent years the industry of high-tech valves and valve industry development trend and investment direction, are as follows:

 



     1. Oil, natural gas wellhead valve devices

 



     Oil, natural gas wellhead valves are mainly used in the U.S. API6A standard single gate or board, there is no diversion diversion hole or holes parallel steel gate valve, ball valve, angle-type throttle valve (CHOKE VALVE ), pilot-type safety valve and check valve.



     2. Oil, natural gas valve with long-distance pipeline



     Oil, natural gas long-distance pipeline with the main valve in order to comply with U.S. standards API6D single-gate or board, there is no diversion diversion hole or holes parallel Forged Gate Valve; steel or cast steel three-body, coat-style or full welded ball valve fixed ball; oil seal or pressure balanced plug valves; Swing check valve or butterfly valve, pass the ball check valve; pigging valve.



     3. Nuclear power plant valve



     Nuclear power than conventional valve with a large thermal power station valve its technical characteristics and requirements higher. Valves are generally valve, valve, check valve, butterfly valve, safety valve, main steam isolation valve, ball valve, valve, relief valve and control valve.

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History of the development of butterfly

The structural characteristics of butterfly valves for the stem axis, butterfly plate center, the Center in the same body position. Simple structure, convenient manufacture. Rubber lining butterfly valve that is commonly fall into this category. The disadvantage is that as a result of butterfly valve plate and extrusion remains, scratch, and resistance from the large, fast wear and tear. To overcome the squeeze, scratch, to ensure the sealing performance, the use of seat basically rubber or elastic material such as PTFE, but also result in the use of restrictions by the temperature, which is why people traditionally do not believe that high temperature valves reasons.      Second, a single eccentric butterfly valve      To resolve the concentric butterfly valve butterfly valve seat plate and the problem of extrusion, the resulting single eccentric butterfly valve, and its structure characterized by a departure from the stem axis center butterfly plate, so that the bottom plate would no longer be a butterfly rotary heart, scattered, reducing the butterfly valve seat on the board over the bottom and squeeze. However, due to a single eccentric valve structure in the course of the entire switch butterfly valve seat plate and the scratch is not disappeared, in the application scope and concentric butterfly valve more or less the same, so the use of small.      Third, double eccentric butterfly valve      In a single eccentric butterfly valve forming the basis of further improvement is currently the most widely used double eccentric butterfly valve. Structural characteristics of its stem axis in both panels deviate from the Butterfly Center, the Center has also deviated from the body. So that the effect of double eccentric valve was opened immediately after the butterfly plate from the valve seat to substantially eliminate the butterfly valve plate and the unnecessary over-extrusion, scratch phenomenon, to reduce resistance from the open and reduce the wear and tear, increased life expectancy seat. A significant reduction in the scratch, but also makes double eccentric butterfly valve metal valve seat can also be used to enhance the area of the butterfly valve in the high-temperature applications. However, because of its location is an enclosed sealed structure principle, that is, butterfly valve seat plate and the sealing surface for line contact plate squeeze through the butterfly valve seat caused by the effect of elastic deformation generated seal, it demanding the closure of the location (especially metal seat), low pressure, which is why people traditionally believe that intolerance of high pressure valves, a large quantity of the reasons for the leakage.

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the development of foreign pipeline ball valve

Pipeline ball valve for half a century after the development of design in the structure of the formation of two schools. One company in the United States on behalf of Cameron, the use of all-welded structure of spherical body. Fall into this genre of BORSIG companies in Germany, Schuck Corporation, the U.S. company Larsen & Toubro, KITZ Corporation of Japan, TIX company, TUBOTA companies, as well as the Ventura Tyazhpromarmatuva Russian companies, in Figure (a) below; another Italian Grove Schools company representatives, the use of split-type tubular structure, and then on this basis to achieve the development of welded tubular body structure, figure (b) below. Fall into this genre of new PIGNONE Italy (Nuovo Pignone), PCC company, PERAR companies, BFE companies, PIBIVIESSE companies, FCT company PBV U.S. companies, the Czech Republic Czechoslovikia company.



 



(A) the United States Cameron Corporation (b) the Japanese company TIX

Figure (a) of the whole pipeline ball valve welding ball valve





(A) the United States PBV company (b) BFE Company

Figure (b) pipeline ball valve cylinder-shaped body



Cameron U.S. technical characteristics of the company's products: All welded ball valve, nylon or PTFE sealing material may be turning the valve seat, stem up and down shaft bearing, import-side sealed the exit pressure cavity to the downstream side discharge automatically. Figure (a) (a) as shown.

Cameron United States in the fifties on the completion of the whole body welding spherical structure, with its high reliability, by half a century of global commercialization of sales, still retains the characteristics of the original structural design and a well-known brands, is widely used in important long-distance pipeline, such as the Alaska oil pipeline.

Grove Italian company to double piston effect, explosion-proof rubber O-rings or PTFE sealing materials, shaft support plate supporting the ball structure, split-type valve, easy maintenance, competitive market position, is widely used in long-distance pipeline station , booster stations. After the development of cylindrical or quasi-cylindrical welded body ball valves in the long-distance pipeline is also used for emergency shut-off valve.

In some cases, the customer needs online maintenance, the use of the pipeline structure to fit the ball valve, Figure (c) below.



Figure (c) pipeline structure to fit the ball valve diagram (d) Japan valves welded spherical TIX

As a result of commercial competition, the promotion of technically merged. Cameron's products Dynaseal 370 is split structure, body welding products with sales support; Grove also introduced a quasi-spherical structure of the whole body welding line is in charge of access to the application. While other companies such as TIX, TITZ while absorbing the merits of two schools, according to the characteristics of their respective manufacturing processes, the introduction of welded ball valve, dual-piston effect, rubber seal material ball valve product line, combines the technical advantages of the genre. Figure (d) below.

 

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Basic knowledge of control valves

1, control valve selection

     A, the importance of control valve selection

     Regulating valve is self-control system, actuators, and its application quality direct response to the quality of the adjustment in the system. As a process control terminal components, the importance in it than in the past has been updated knowledge. Control valve applications, good or bad, in addition to the quality of the product itself, the user is installed correctly, use, maintenance, correct calculations, selection is very important. Selection of calculation errors, causing the system to open stop-open, and some can not even put into use, so for users and system designers should be aware of the importance of valves in the field, control valve selection must be taken seriously enough.

     B, the principle of control valve selection

     1, according to process conditions, selection of suitable structural forms and materials.

     2, according to the technical characteristics of the object, select the control valve flow characteristics.

     3, according to process operating parameters, select the appropriate aperture size control valves.

     4, according to process requirements, select the required assistive devices.

     5, selecting the implementing agency. The response speed of the implementing agencies should be able to meet the technical

     To control the travel time requirements: the selected implementing agency should be able to control valves sounded very full schedule and process on the valve leakage volume level requirements. In some cases, such as the selection of pressure control valves (including the venting valves), pressure should be considered possible and practicable, appropriate amplification, which would require implementing agencies to provide a larger force. Otherwise, it may appear abnormal when the process occurs, the actual differential pressure control valve before and after the larger, will occur o ball valve Trunnion Mounted Ball Valve Floating Ball Valve Top Entry Ball Valve Three way ball valve V Type Ball Valve
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New high-life characteristics of stainless steel butterfly valve

 At present, the butterfly valve is used to achieve piping system as an on-off and flow control components, has been in the petroleum, chemical industry, metallurgy, water, electricity and many other areas to be very widely used. In the known butterfly has been recognized technology, its sealed form of multi-sealed structure, sealing material for rubber, PTFE and so on. As the structural characteristics of the restriction is not suitable for high temperature, high pressure and corrosion resistance, abrasion resistance and other industries.

     Present a more sophisticated three eccentric butterfly valve is metal seal butterfly valve, valve and valve seat as the Siamese components, valve seat sealing surface layer welding temperature, corrosion resistant alloy material. Soft-stacked multi-ring fixed to the valve plate, this butterfly valve in comparison with the traditional high temperature, easy operation, open and close without friction, closed with the transmission of the torque increases to compensate for seal, to improve a butterfly valve sealing performance and durability advantages.

     However, this butterfly is still in the course of the following problems:

     1, due to soft and hard stacked multi-ring fixed to the valve plate, when the valve plate to its normal open state media, the formation of a positive sealing surface erosion, and metal sheets laminated in the soft-sealing tape subject to erosion, the direct impact on seal performance.

     Second, by the structural conditions that limit the structure do not meet the following diameter DN200 valves, because the overall structure of valve plate thick, large flow resistance.

     Third, because the principle of the three eccentric structure, the valve plate sealing surface and the seal between the valve seat is to rely on the torque transmission device so that pressure valve plate to the valve seat. Positive flow state, the media, the higher the pressure squeezed more tightly sealed. When the flow channel upstream medium with medium pressure increases when the valve plate and seat the pressure between the units is less than the medium pressure, the seal started to leak out.

     High-performance 3-way eccentric hard-seal butterfly valve, its characteristics are: described by a soft T-shaped valve seat ring seal ring on both sides of the composition of multi-layer stainless steel sheet. Valve plate and valve seat sealing surface for the oblique cone structure, in the valve plate oblique cone surfacing temperature, corrosion resistant alloy materials; fixed platen in the regulation of rings between the spring and the adjustment bolt assembly with the platen structure. This structure effectively compensate for the tolerance between the sleeve and the valve stem in the medium zone and the elastic deformation under pressure to solve the two-way valve in the transmission medium of exchange that exist in the process of sealing problems. Use of soft T-seals on both sides of the composition of multi-layer stainless steel sheet with a metal seal and soft seal the dual advantages of both the low and high temperature cases, both with zero leakage sealing performance.

     Test proved positive flow state (medium flow direction and the butterfly plate rotation in the same direction), the sealing surface pressure is the transmission of torque and media pressure on the valve plate of the role of the elected. Positive medium pressure increases, valve plate oblique cone surface and the valve seat sealing surface squeezed more tightly, sealing the better. When the counter-current state, the valve plate and valve seat through the seal between the drive torque to the valve seat so that pressure valve plate. With the reverse-media pressure, valve plate and valve seat unit between the positive pressure is less than medium pressure, the adjustment of the spring ring is contained in the subject after the deformation energy stored in compensation valve plate and valve seat sealing surface of the tight the pressure to play the role of automatic compensation. Therefore, this utility model, unlike existing technologies, as the valve plate to install software and hardware multi-ring, but directly installed on the valve body, in the platen, and the middle seat an additional adjustment ring is a very good two-way hard-sealing method . It can replace valve, the cut-off valve and ball valve. 

  ball valve Trunnion Mounted Ball Valve Floating Ball Valve Top Entry Ball Valve ball valve V Type Ball Valve
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The issue of water supply pipe network of valves

Water supply network to send the water from the waterworks distribution to millions of households, so the distribution of water supply networks in cities in every corner, at least hundreds of kilometers of its length, up to thousands of kilometers.

Irreplaceability of water and necessary for people to live, and determined that the water supply network of the importance of safe operation. However, due to various objective and subjective reasons, the pipeline tends to be some failures, pipe network is always to keep upgrading, water users often have a change, so the local control of water above it is difficult to avoid the phenomenon. In order to narrow the scope of water in the pipe network due to the installation of control valves is necessary. Therefore, in a city's water supply network, the number of tens of thousands of valves, there is no regular distribution in the city streets below.

Water supply pipe-line operation of the valve is not frequent, long-term standby, if necessary, should be able to close the valve rapidly, a reliable closure; usually request to open the valve should be in place to reduce the head loss pipe sections, so the valve is a kind of "Yang-bing A Thousand Days, 1:00 troops "of the control equipment; the good rate of valve related to the selection of valves, valve manufacture, pipeline design, the valve assembly, the gate valve and valve management, The main reason of course is the quality of the valve.

Valve in the water supply network in the large number of widely distributed, the role of big. As a result, valve selection, testing, performance and management of many of the issues are worthy of discussion.

First, the selection valve

     There are butterfly valves, gate valve, ball valves and plug valves, such as several in the water supply network in the scope of the use of different. In order to reduce the pipeline depth of soil, the larger diameter pipes generally matching butterfly; little effect on the depth of soil to matching valve; ball valves and plug valves casting and machining difficult, expensive prices, generally applicable to small and medium-caliber pipe. In recent years, due to improvements in casting technology, the use of resin sand casting method can be avoided or reduced machining, thereby reducing the cost, so the ball valve for large diameter pipe is worth exploring the feasibility. As for the size of the line diameter should be considered throughout the division by the specific circumstances.

The main disadvantage is the butterfly butterfly board to occupy a certain cross section, add the head loss; valve no problem, but the large-diameter vertical pipe valve of a high impact on the soil depth of large diameter horizontal valve increased the length of horizontal pipe occupied area, the impact of other arrangements for the pipeline; ball valves and plug valves are maintained single valve, the flow resistance in small, sealed reliable, flexible movements, operation and maintenance of the advantages of convenience. Plug valves also have similar advantages, but not the cross section is circular.

In recent years, many valve manufacturers to develop soft-sealed gate valve, the valve and cut the traditional or parallel plate gate valve双闸compared the following characteristics:

1. Soft sealing valve of the valve body, valve cover the use of precision casting foundry, a molding, it is no longer machining, non-use of sealed铜环, saving non-ferrous metals;

2. Soft sealing gate valve at the bottom of pit-free, non-accumulation of Java objects, the gate valve failure rate is low;

3. Soft rubber lining the valve seal uniform size, strong interchangeability.

So soft sealing gate valve gate valve will be the development direction of the water supply industry is also reluctant to adopt a kind of valve. Soft sealing gate valve, the closure should not have to die, as long as the sealing effect can be achieved, otherwise difficult to open or peeling rubber lining.

Water supply industry is mostly used in soft-sealed butterfly valve butterfly valve, butterfly valve for the apron during the installation process easy to damage the impact of tightness, the introduction of many manufacturers to replace metal seal butterfly valve butterfly valve sealing apron. Metal seal butterfly valve seals due to the flexibility of small, generally eccentric structure, especially the use of three-dimensional structure is more reasonable eccentricity.

Second, the performance and test valve

The specificity of valves require reliable quality and performance. Performance evaluation of valve performance testing and should note the following:

1. Water pressure valve in the workplace under the headstock flexible, lightweight, water pressure in the work of testing using a torque wrench torque to open.

2. Valve tightly closed, in the 1.1-fold under the pressure of work does not meet the criteria for leakage or seepage requirements (metal sealed butterfly valve), which requires both sides of the rotation pressure valves were used to detect, and many sluicegate achieve the same effect. Requirements of various calibres, different types of valve manufacturer shall be qualified and have a detection unit with the life span of the load detection headstock. This testing also includes the effect of the valve shaft seal evaluation.

3. Better-off valve flow capacity, in particular, butterfly, butterfly plate flow resistance to small, over-current, to a large effective area. This requires a variety of voice, different types of valves should be the determination of flow resistance coefficient.

4. Body's ability to bear the water pressure should be consistent with the pipeline, that is, open the valve, the valve can withstand the test pressure pipeline requirements.

Third, valves lining and outer anti-corrosion

Is the transmission valve drinking water equipment, body lining must be non-toxic, corrosion-resistant, wear-resistant, smooth flow resistance as small as possible. If the valve plate, bolts and butterfly plates of different materials, it is prone to electrochemical corrosion, corrosion rust generated extending to the sealing surface, affecting the sealing effect of the valve, and valve wells installed in the valve, soak in water to prevent corrosion It is important, therefore, to cover perfect lining to prevent corrosion of the secondary pollution caused by water.

Valves can be taken outside the anti-corrosion after polishing sand-ching, for electrostatic spraying non-toxic anti-corrosion epoxy resin, can also brush 1-2 times Hongdan paint, brush and then twice in Antirust Paint.

Fourth, the valve operation and management

Good gate valve can not only appropriate valve selection, product quality, well construction and installation, but also thoughtful management, in order to play the role of "A Thousand Days Yang-bing, war time" effect. Good operation and management reflected in the following three aspects:

     1. Technical details are available

Valve valve factory technical information, including manuals, test the valve after the purchase of single-pass, valve assembly and the location of cards, valve maintenance record. Changes in the streets, the valve should be to update the card to establish a GIS management system.

2. Valve Operation and Management thoughtful

     Valve operation and management of quality requirements, including the valve should be closed tightly, the valve rod shaft seal packing string Department does not leak, the valve gate lightweight, well-directed. Valve operation and management of day-to-day operations, including gate valve, single previous approval of the records and operational records of the perfect, periodic testing of the gate valves and other records. Not for long-term operation of the valve off, according to the size of caliber, for the detection of different cycles is necessary. The fault should be found in the maintenance program, in time, especially after the closure of the valve can not open, like a burst pipe repairs as an emergency to deal with.

3. Well valve in good condition

Well the situation of valves including valve masonry well in line with industry standards and design specifications, and covers the road convergence intact, operate the valve hole bit accurate, wells and sewage debris-free, valve-free锈斑surface. Conditions permit, large diameter valves wells wells should be considered long-term convection air can be technical measures. Well on the valve should be inspected regularly, and covers the loss and damage should be dealt with promptly. 

  

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valve problems and the prevention of

Often happens after the factory valve problems caused by supply and demand should be the concern of both sides.

1, improper storage of

Valve can not open storage, should be placed in ventilation, dry place, the manufacturing plant, storage time should be required, to remove the valve can not be stored at both ends of the protective cover.

Lifting the valve actuator can not be as a lifting point, the attention can not be bumps flange.

2, the installation of inappropriate

Can not be used to support pipeline valves, flanges or welding to install client when the response to Qi, the pipeline to prevent stress caused by thermal expansion value.

3, improper welding

In accordance with the norms of the correct welding process;

Control of welding temperature, to prevent the sealing material damage.

Solder sealing ring before the Department with butter spread, the application of welding base to prevent welding spatter material embedded in the sealing surface.

4, start the process of the damage

Before the opening of the pipeline to be cleaned to remove dirt pipe rust, sediment, foreign body, to prevent damage to the sealing surface.

Valves can not for long remain in the semi-open semi-closed position.

Strength tests in the pipeline, be sure to complete emptying of liquid, the water valve will lead to chloride corrosion, strength test of the chloride content of the water required to control and add anti-corrosion agent.

5, the use of improper

Off valve can not be used to regulate flows, and is strictly prohibited in the semi-open semi-closed state of the use of wide-open valve position should be maintained at the location or total clearance.

6, corrosion

Selection of valve manufacturing and media must be considered H2S content and chloride content, material selection and heat treatment must comply with NACE MR-01-75 requirements

7, inappropriate choice of sealing materials

Selected as a rubber O-ring seal material, for pound Class600 level and above should be verified with optional explosion-proof vacuum (AED) of the material properties.

8, transmission problem

Valve position is not in place a recurring problem, the manufacturer must ensure that every aspect of transmission chain of the manufacturing accuracy, especially the pole then the ball valve, check valve before the factory switch location and the location of the consistency of instruction. valve ball valve gate valve check valve globe valve butterfly valve
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Standard pipeline ball valve

Pipeline ball valve design, manufacture, test specification standards are API standard 6D, the standard proposals for oil and gas industry to meet international standards of ISO13623 requirements of pipeline systems, the corresponding national standard is GB: 1, Full Bore or reduced bore diameter size according to the API standards 6D. 2, pipeline pressure valve according to API standard grade 6D, pressure temperature rating by ASME16.34. 3, a long pipeline to connect the valve according to API standards and tolerances 6D. 4, flange end of the size 24 "The following ANSI B16.5; 26" or above by ANSI B16.47. 5, butt welding end size according to ASME B 16.25. 6, flange face processing in accordance with ANSI B16.5. 7, excretory pore and the discharge hole diameter according to API standards 6D. 8, pressure test according to API Standard 6D and API Standard 598. 9, the fire safety design and test in accordance with BS6755, Part II; API Standard 607, API standard 6FA. 10, the material should be in accordance with ASME standards, as well as the corresponding NACE MR 0175, NACE MR 0103 standard. 11, valves and welding in line with the ASME Boiler Pressure Vessel Code section IX Welding and Brazing volume assessment, BS7448 Part II fracture toughness tests. 12, valve testing in line with the ASME Boiler and Pressure Vessel section V non-destructive testing, vol. 13, valve tags shall be in accordance with MSS-SP-25 or API Standard 6D. 14, ASME Boiler and Pressure Vessel Code section VIII rules of volume pressure vessel manufacture.

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Water supply network to choose the valve (a)

Water supply pipe network is all kinds of pipes and valves and other pipeline accessories, which consists of parts. According to a variety of needs (the water pipe network, the scheduling and allocation of water pressure, maintenance, repair of the water needs of old and new pipeline connections, pipeline cleaning, etc.) every day for the opening and closing valves. And quality of life of the valve determines the normal operation of networks in the pipe network plays a central role in the need to pay close attention.



As the water supply pipe network is connected between the enterprises and the users of the bridge, it can say: a water quality of enterprise management network in the normal operation; and the water supply network of the normal operation, but also and valves and quality of life is closely related to the.



Below the water supply network on the valve selection, offer a few comments.



1, the safety of water supply



Valve does not affect the water quality is an important indicator of choice. Valve direct contact with water is some of the main body inside, sealing parts, valves, etc., many valve manufacturers rubber sealing parts. Commonly used rubber material is nitrile rubber (NBR), chloroprene rubber (CR) or ethylene-propylene rubber (EPDM). These rubber is synthetic rubber. In the synthesis process, to add more than 10 kinds of natural rubber materials and additives, etc. Anti-aging. Can the ultimate synthesis of rubber seal for the water supply valve must be to see whether such a non-toxic rubber, with the drinking water health standards. As for the inside of the valve and valve parts, etc., many manufacturers of the past methods of painting, only the rust problem, without considering whether or not toxic. In practice, we find that: the water supply network, the pipeline corrosion problem lining, and pipe network is not lined valves, due to the phenomenon of water and the precipitation of iron bacteria in the water valve and the valve cavity and the erosion deposition, resulting in a number of body wall-like hills there depositions. Not only affected the quality of water supplies for a number of valves at the same time one of the main reasons poor clearance. Therefore, we ask, they come in direct contact with the water areas, should be non-toxic paint spraying, electrostati
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Unloading Relief Valve works with the primary purpose

 Unloading relief valve formed by the relief valve and one-way valve. When the system pressure to reach the opening pressure relief valve, relief valve opens, pump unloading; When the system pressure dropped to the closure of pressure relief valve, relief valve closed, pump to the system load. Unloading the pump when the pressure is called unloading pressure, so that the pressure pump in a loaded condition is called load pressure.

     Functions and Applications: The main function of unloading relief valve is the automatic control of pump unloading or loading. In view of the function of unloading relief valve to require unloading pressure and there are some differences between the load pressure. The difference is too small, then the unloading and loading pump action too frequently; the difference is too large, the system changed so much pressure.

     Load pressure and the pressure difference between unloading unloading relief valve is an important performance indicators, the general pressure loading unloading pressure of about 85%. The same as with the relief valve performance.

     Unloading relief valve of the main purposes:

     a. Accumulator pump system automatically unloading and loading;

     b. combination of high and low pressure pump high flow low pressure pump unloading.

     Manufacturers produce goods: domestic mainly Yuci hydraulic Group Co., Ltd., Beijing, China and Germany Hydraulic Group Co., Ltd., Shanghai Lixin Hydraulic Component Factory and so on. Outside the United States Vickers, Rexroth, Germany and other manufacturers.

     Unloading relief valve Germany choice: unloading relief valve used in hydraulic circuit with accumulator Germany, when the accumulator valve fluid-filled pressure of Germany set the pressure so that hydraulic pump unloading automatically. Valves have built-in check valve to prevent a pressure accumulator in the oil back. At this point from the accumulator and the pump to maintain oil unloading system to receive energy-saving effect. When the accumulator in the oil pressure dropped to the valve set pressure to about 85% when the valve is once set, hydraulic pump to restore the accumulator fluid-filled.

     This valve can also be used to double-pump high-low voltage circuits. When two low-pressure oil pump to the system at the same time, high pressure pump when the valve so that the major unloading and separating it with the high-pressure section.

     For the accumulator to the accumulator between the valve and shall not exceed the set pressure to drop to 10%. Leakage-type valve to vent the oil port back-pressure shall not exceed the set pressure to 2%. ball valve Trunnion Mounted Ball Valve Floating Ball Valve Top Entry Ball Valve ball valve
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A lot of market opportunities

 The international valve market can not tolerate us? Clearly not. It is understood that the Middle East as the world's most important oil-producing and exporting region, every country in the efforts to enhance oil production, but also increased the exploitation of oil and investment. The next few years in the north of Kuwait's largest oil and gas development projects currently in progress; Qatar will be the world's largest liquefied natural gas plant products; the United Arab Emirates through the construction of large-scale projects to increase crude oil production, crude oil production is expected to more than three million barrels; Abu Dhabi National Oil Company in the next 5 years a number of projects on an annual investment of 1.5 billion U.S. dollars, of which 40% for the oil industry ... ... and the requirements of each and every project is the largest valve products. On the other hand as a result of the Middle East, the Iraq oil fields, pipelines destroyed a powerful need to import oil by pipeline systems and valves, including API ball valve, gate valve, butterfly valve, check valve, globe valve,flat long-distance pipeline valves and ball valves and so on. These are the domestic valve manufacturer's main product is our strength. Why do we not get to do the business of their own this?

    

     Station to be eligible for future

    

     In fact, that as long as the needs of the market, domestic enterprises have become the valve of the international market is the key to great advantage. As long as the proper way, we can be our own station to the market prospects for the market to act as the protagonist.

    

     First export. Exports, including direct exports and indirect exports. Refers to the direct export products directly to businesses in the international market. It also has two ways: First, through foreign brokers, sold to local markets. The second is to set up their own enterprises in the foreign sales agencies, directly to the products sold to local customers. Indirectly refers to the export of domestic enterprises to export their products broker. The export is one of the most simple choice, it does not require full-time中售员and does not require huge capital investments, and flexibility, with less risk. But is also very obvious shortcomings, that is, companies can not directly involved in international sales activities, out of control on the export market, the market is limited feedback on the changes in the market it is difficult to make timely adjustments.

    

     Second, trade permits. Permit trade is granted by an authorized person has been authorized the right to have commercial value or technologies, including trade marks, patents, proprietary technology the right to use and so on. Valves due to the lack of domestic corporate management experience, a well-known brands and unique technology, use of the small. But it is also a direction of development, we can urge the companies to cultivate their own brands with independent intellectual property rights and development of technology.

    

     Third, foreign direct investment. Foreign direct investment refers to the actual ownership and control of foreign enterprises to participate directly in its management. From the equity point of view, it has two different forms, such as joint ventures. Refers to a joint venture enterprises in foreign markets with local businesses to operate a joint venture enterprise. Joint venture of local firms through the purchase of equity or co-financing a new business. The advantages of joint venture income larger, corporate marketing and production of control and market feedback. The disadvantage is that often a result of a partnership between the production and marketing have different views on the contradictions arising.

    

     Also such as sole proprietors. A sole proprietorship is an enterprise set up an independent production abroad. It can be through direct acquisition of existing local enterprises, can also create a new business. Owned enterprises can enjoy the advantages of the profits to obtain more experience in international marketing and market opportunities, the parent company of overseas subsidiaries have complete right to manage and control. The disadvantage is that large investment risks, uncertainties and more.
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Control valve stem seal of the new method

1, Introduction



Control valves, automatic control system is a very important, like people's hands and feet. Regulation of fluid flow control valve to overcome the interference to ensure the accused of variables to achieve a given process indicators.



Control valves by the valve inside the valve body parts and the composition of the inner valve spool pieces, including, stem, packing on the valve cover letter and so on. On the valve cover and fill for the letter of the stem seals and valve stem to guide, to prevent the process medium along the valve stem to control the outward leakage of movable parts, it is an integral part of valve body.



Conventional structure of the valve cover there are four general forms: ordinary type, heat sink type, long-necked and bellows-type seal. Materials are generally cast iron, cast steel and stainless steel, PTFE packing or letter is generally flexible graphite.



A typical control valve of the valve cover and valve body from the same material or equivalent material. Valve cover and valve body to bear the same temperature and corrosive effects of stem seal after a few hundred times after the cycle of action, they will wear, in engineering applications, the fluid pressure can lead to seal wear and tear; fill the choice is also a problem filling materials selection, control valves, increasing the friction caused by dead-zone control valves easily increase or stem seal failure.



Therefore, the choice of control valve, in addition to body structure, material, implementing agencies, the calculation caliber but also under the control of fluid pressure, temperature, pressure, fluid nature, a reasonable choice of the structure of the valve cover and fill the form of letters to to prevent fluid leakage along the control valve stem out, that should give full consideration to stem seal performance and service life. This is in engineering design it is very important.



Corrosion in strong, volatile and toxic and hazardous fluids in the process, control valves are generally not the ordinary type, heat sink type, long-necked type seal on the valve cover and structure, because such a structure of sealing performance and life of great limited. The author has done the scene in the production of related experiments, the use of 304 stainless steel control valves regulate straight trip concentrated nitric acid and concentrated sulfuric acid mixed acid flow, the use of PTFE packing seal structure, less than a month after about 600 of the control of the entire trip valve up and down movement of the rod, PTFE packing seal that is completely undermined. Corrosion in strong, volatile and toxic and hazardous process conditions, once the stem seal is damaged, strong corrosive, volatile and toxic and hazardous process media control valve stem from leaking out on the surrounding environment and personal security serious consequences.



Adopted the form of bellows-type seal of the problem is a way. Bellows made of stainless steel in general. This special structure to protect the valve cover of the fill control valves and fluid contact with you to avoid, once broken bellows, the bellows structure of the above letter will fill the bellows to prevent the breakdown of failure have serious consequences. In engineering practice, the form of bellows seal selection should take full account of the pressure of bellows sealed the rating would be higher with lower temperature, fluid particles can not have a solid presence, and corrugated pipe materials, such as the longest life cycle of action . Intolerance of certain processes in the stainless steel corrosion medium places strong corrosion, such as wet chlorine process medium, the wetlands of trace chlorine in hydrochloric acid containing stainless steel corrugated pipe will soon be corrosive, it can not be used to control valve stem bellows sealed form.



In this case, the right to choose seems to be the use of diaphragm control valve. Diaphragm control valves used in corrosion-resistant and corrosion-resistant lining membrane, do not fill, you can completely avoid the leakage of corrosive media field, but its not very good flow characteristics, and by the membrane lining of the restrictions, pressure, low temperature performance The most deadly is corrosion-resistant film will divide up and down folding as a result of damage caused by fatigue, a very short life span, once piece corrosion-resistant diaphragm rupture, strong corrosive, volatile and toxic and hazardous process media will be the same Department from leaking out of cracks, so diaphragm control valve by the use of a lot of constraints.



Therefore, in strong corrosion, volatile, toxic and hazardous process conditions, to find a reliable, economical and practical control valves on the valve cover and seal structure is to ensure reliable control valves work in order to achieve automatic control of the key production processes. 2, a new type of control valve stem sealing method



Nitrocellulose nitrification process that concentrated nitric acid and concentrated sulfuric acid and cotton fiber mixed reaction Nitrocellulose, control of concentrated nitric acid and concentrated sulfuric acid mixed acid flow and the ratio of the volume of cotton fiber is to ensure that the key to Nitrocellulose product quality. Nitrocellulose nitrification processes in the transformation of self-control system, we designed a new type of stem seal and successfully resolved the regulation of concentrated nitric acid and concentrated sulfuric acid mixed acid flow control valve stem seal problem.



PTFE packing seal in the top, we designed a cavity and the cavity to pass into the inert gas (such as nitrogen, can also be air), and requested the pressure inert gas pipeline to be slightly higher than the process the maximum pressure medium. In this way, control valves in the use of the process, even if the control valve of PTFE packing seal is damaged, due to the pressure of the gas pipeline to be slightly higher than the maximum pressure on media technology, strong corrosive, volatile, toxic and harmful gas can not leak out. Cavity in order to ensure the stability of gas pressure to prevent the gas valve stem up and down along the string gas in the cavity of the lower part of the PTFE packing divided into two parts from top to bottom, in the middle of a stainless steel pad traps will Viton O - stainless steel ring embedded in every other pad, the pad separated using PTFE packing its clamping. The upper cavity of the valve cover is also embedded in fluorinated rubber O-ring, and valve cover bolts will be pressed. In general, the fluorine rubber O-ring of life is relatively long, up to a million times, as long as the fluorine rubber O-ring seal is not damaged, cavity pressure inert gas pipeline technology has always been higher than the medium the highest pressure, the control valve stem sealing structure is very reliable and very economic.



3, Conclusion



That the control valve sealing structure in 2001, the company successfully used a modified nitrification process automatic control system, the realization of the production process of the nitrification process automation, control valve operation so far and there have never been as a result of the control valve stem packing seal damage resulted in concentrated nitric acid and concentrated sulfuric acid mixed acid along the valve stem to control the leakage of the accident.

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Valve leaked on the use of simple pre-installed on the technical requirements

Technical requirements for installation:



1, the valve should be installed before the cavity clean and remove the defects caused by transport;



2, leaked butterfly valve shaft is installed to maintain the level of the state was, piston valve upward vertical position;



3, the valve gear to deal with the use of pre-debug, and maintain the function of transmission intact, the limits of travel and over-torque control and reliable protection;



4, valve gear parts of the lubrication necessary to fully debug the use of pre-lubricating;



5, activated electric devices should carefully read the random electrical installation manual provided. 

  

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Automotive engine control valve of the principle of waveform analysis of fault (a)

1. Idle Speed Control (IAC) solenoid valve



Idle speed controller is designed in a number of mechanical and electrical and mechanical installations, in the electronically controlled engine management system, electronically controlled thermostat to replace the old plug, paraffin-type, vacuum tank, such as the location of similar devices. Idle speed electronically controlled solenoid valve to prevent idling of the stall, and enhance the stability of idling in the slow speed means used to reduce the classification of hydrocarbon HC emissions. Idle solenoid valve to maintain the idle speed as low as possible and not put out, even in the open air-conditioners, generators, ancillary facilities such as power steering increase the engine load can also be possible to maintain stability.



Idle speed controller is a number of solenoid valves (most Ford vehicles) and some rotary motor (European Bosch BOSCH), others are stepping DC Gear Motor (most applicable, Chrysler), but all the examples are by the control computer to change the signal amplitude or pulse width to the ultimate control of the operation of idling.



Idling by the sensor to detect engine speed, idle speed be adjusted in a predetermined set of procedures to maintain paragraph. Control of the computer such as air-conditioning compressor from the switch, battery charging indicator, power steering switch and the free / parking block of ancillary equipment such as switches to receive the digital input signal switches, each switch will trigger the compensation is scheduled to set the idle command and send it to idle speed controller, engine speed when the throttle to close to or below the minimum speed stability, Idle Speed Control system came into play often, electronically controlled idle air bypass the throttle valve to allow the flow to produce results similar to open throttle.



Test Method:



To make the engine idle operation and ancillary equipment (air conditioning, fans, wipers) on or off, if equipped with automatic transmission car in the parking stalls and switch between forward. This will change the engine load, causing the engine control computer to the idle valve to change the output command signal.



Waveform results:



Confirmed that compensation for a variety of idle mode waveform amplitude, frequency, shape, pulse width of scale, such as are found in the right context, and the repeatability and consistency.



Confirmed when the control signal changes the computer's command, the solenoid valve response, and changes in engine speed has also observed the emergence of the following circumstances:



Switch when the proportion of ancillary electrical equipment to open or close the block to block transmission, the control computer to control the idle speed will change the output command. Idle speed changes, Idle Speed Control Valve should open and close throttle bypass hole, if the idle speed remains unchanged, should doubt the next idle valve damage or obstruction.



Idle Speed Control valve in the diagnosis and control circuit, we should make sure that section of the vacuum leak check the air leakage or inappropriate, they will idle control system problem. 

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Smoke damSmoke damper valve applications in engineering quality requirements (c)

3.2, the installation of quality requirements



In day-to-day inspection of fire inspection and engineering work, I found the construction quality problems due to the installation of smoke caused by fire or valve failure to open problems, exhaust valves, exhaust port, fire dampers, fire reset Tuyere difficulties. This should be of great importance to the construction side, note the following installation requirements.



3.2.1, fire damper, exhaust valve should be strictly according to plan the construction of a separate hanger for support in order to avoid air duct at a high temperature deformation, the impact of valve function.



3.2.2, valves in the ceiling or in the installation of air duct should be on the board in the ceiling or walls of air duct into the hole for maintenance, the general into the pore size of not less than 450 × 450mm, in the conditions, the ceiling manholes can be reduced to 300 × 300mm.



3.2.3, fire damper and a firewall (or floor) between the duct should be used δ ≥ 1.5mm steel plate production, then the best for external use in the wind pipe insulation or refractory materials incombustibility protection, to ensure that firewall fire-resistant properties.



3.2.4, in the mechanical side of the operation of the valve should have a clear space of 350mm in order to facilitate maintenance.



4, fire, smoke valve in the works of some of the problems that exist in



I built the fire in the day-to-day trial, engineering check and acceptance work, found fire and smoke valves have a number of problems in the following for peer reference.



4.1, the fire control room to send the return air duct in his Department does not have to wear fire damper wall.



Pre-trial process in building and found that some of the works on the design of consumer control room to send back to the wind pipe through walls Department in its non-damper, which is "automatic fire alarm system design specifications" GB50116-98 in the first inconsistent with Article 6.2.2. For the purpose of fire damper fire control room in order to ensure fire safety.



4.2, fire control equipment to smoke, smoke control facilities, display imperfect



GB50116-98 in accordance with norms of the first provisions of Article 6.3.9: Fire Alarm confirmation, to stop supply of the parts of the air-conditioning, electric fire damper to close and receive the feedback signal; At the same time to start the relevant parts of the smoke and exhaust fan , exhaust valve, and to receive the feedback signal. Some projects can not be linked to control sub-control exhaust valves, exhaust port, and some can not receive the feedback signal, valves do not reflect the situation of the headstock.



4.3, pipeline gas fire extinguishing system without pneumatic damper.



GB50116-98 the first 6.3.4.3 requires: "In the delayed phase, should be self-closing fire doors, windows, ventilation and air conditioning system to stop the closure of fire dampers on the site." This requires a network of gas fire extinguishing system, must be installed on gas Dynamic fire dampers, and fire control equipment linked. In the absence of such features in the individual projects.



4.4, air supply and exhaust duct without sharing the remote control



The basement of some building, car parks combined use of air supply and exhaust duct, we found blower and exhaust valve in front of the scene can only manually, the control room of the remote control can not be achieved in normal times, blower, its front end valve was open the situation, in the event of fire, will take people to the scene to close the fan before the cut-off valve, which is very practical, directly affect the extraction system. Therefore, it is proposed to increase its cut-off valve remote control functions.



5, system debugging and maintenance and management of linkage



Fire damper, exhaust valve works in practice is not independent of Fire smoke products, but in the entire fire control system of linkage has its own unique logic of the relationship between linkage. Therefore, in order to ensure that its fire-fighting system to play a role in the system prior to acceptance by linkage requirements, must be fully debug, so that ventilation and air conditioning and smoke control system to meet regulatory requirements. Person should be carried out after acceptance of a planned day-to-day maintenance and management in order to protect the body in a normal situation, in the role of smoke in the Fire play their full role. 

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Knowledge of control valves

 Control valve control valve is also called, is the main type of actuator, control unit regulating the output by receiving the control signal, using power-operated to change the fluid flow. Regulating valve and valves are generally composed of the implementing agencies. If you press it with the implementing agencies to use power, control valve can be divided into pneumatic, electric, hydraulic three kinds, namely, the source of compressed air-powered pneumatic control valve, to electric power source for electric control valve in order to liquid medium (eg oil) pressure-powered electric hydraulic control valve addition, according to their functions and features points, as well as solenoid valves, electronic, intelligent, fieldbus-type regulating valve.

     Control Valve Body type selection

     Many different types of control valve body, often there are through single-seat, through two-seater, angular, diaphragm, small flow, three-, eccentric rotation, butterfly, sleeve type, ball and so on. Specific selection, do the following considerations:

     (1)阀芯中形结构

     Mainly based on the selected traffic characteristics and take into account factors such as unbalanced force.

     (2) The wear resistance

     When the fluid medium that contain high concentrations of abrasive particles in suspension, the valve's internal materials to be hard.

     (3) corrosion resistance

     As the medium is corrosive, as we choose simple valve.

     (4) medium temperature, pressure,

     When the medium temperature and pressure variation in high and when the valve core and valve seat should use the material by the temperature and pressure changes in the small valve.

     (5) Prevention of flashing and cavitation

     Flashing and cavitation produced only in liquid medium. In the actual production process, the flashing and cavitation will form vibration and noise, shorten the life of the valve, so the choice should be to prevent the valve produces flash valve and cavitation.

     Control valve selection of implementing agencies

     In order to control valve to work, with executive body used to be able to generate sufficient output power to ensure a high degree of sealing and the valve opening.

     For the double-acting pneumatic, hydraulic, electric actuator, generally do not reset spring. The size of the force direction has nothing to do with its operation, therefore, selecting executing agencies is the key to understand the maximum output power and the motor rotational torque. For single role of the pneumatic actuator, the output force and the opening of the valve, regulating valve on the emergence of the force will also affect the motion characteristics, thus requiring the entire range of control valve opening to establish the force balance.

     Implementing agencies to determine the type of

     Output force of the implementing agencies to determine, based on the use of environmental requirements, process, select the appropriate enforcement agency. For the scene, where explosion-proof requirements, should use pneumatic actuator. From the energy-saving considerations, should try to use electric actuator. If the adjustment of high precision, optional hydraulic enforcement agency. Speed machines such as power plants and transparent regulation, the refinery's catalytic cracking unit reactor temperature adjustment control.

     Mode of action of regulating valve selection

     Mode of action of control valve selection of pneumatic actuator only when they left, their mode of action through the pros and cons of the role of implementing agencies and valve combination of positive and negative role in the formation. There are four kinds of combination that is precisely (gas off type), the pros and cons (gas open type), anyway (gas open type), anti-anti-(gas off type), through the formation of these four combined mode of action of a gas control valve Open off two kinds of gas. For the choice of mode of action of control valve, the main three-pronged approach to consider: a) process production safety; b) characteristics of the medium; c) to ensure product quality, minimize economic losses.

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Valve repair and maintenance of power plants

Sealing Technology for Thermal Power Plant Valve Pressure

     Power plant valve is mainly used for control of various equipment and its control on the road fluid medium of operation, the valve leakage often occurred in the filling, sealing and the valve flange, the valve leakage can cause a long stem and flange sealing surface erosion, which will ultimately enable the valve scrapped, coupled with the loss of fluid medium, so that power consumption increased, rising costs, economic decline. Medium fluid, if toxic, flammable, explosive, corrosive, etc. outside the leak occurred, then prone to poisoning, fires, explosions and other casualties and accelerate the corrosion rate of plant and equipment and shorten its life, and in severe pollution of surrounding environment, destroying the power production and damage to people's health. There is a serious threat to the leakage of safety in production, so that power plants increased incidents of unplanned downtime. The following are some causes of valve leakage and plugging methods and the right valve repair and maintenance methods, for reference.



     2 valve leakage in the form of and factors



     2.1 The valve packing leakage and the reasons for



     Valve in operation during use, the stem with the relative movement exists between the filler, which includes rotation and axial movement. As the switching frequency increases, the number of relative motion also will be increased, as well as temperature, pressure and fluid characteristics of the medium such as the impact of the valve packing is the most prone to leak the site. It is the contact pressure due to the gradual weakening filler, filling their own aging, loss of elasticity causes. Then the pressure medium will be along the gap filler out of contact with the valve stem leaks, blown away a long time that some of the fill and will stem carve out grooves, so that leakage of magnification.



     2.2 Flange leak



     The valve connecting flange sealing relies mainly on the preload bolt, through the sealing gasket to achieve more than enough pressure, the pressure to be sealed to prevent leakage of fluid medium. There are many reasons it is leaking, the sealing gasket of the lack of compaction force, combined with surface roughness does not meet the requirements, gasket distortion and mechanical vibration, such as would give rise to sealing gasket and flange surface density combined with lax and happened leakage. Another deformation or elongation of bolts, gaskets aging, resilient fall can also cause cracks and other flange Mifengbuyan the leak. Flange leak there can not be ignored human factors, such as the sealing gasket mounted side, so that partial pressure less than the tight seal of excessive force, exceeding the design limits of the sealing gasket, as well as the uneven force during fastening flange or two France Lan centerline offset, resulting in the phenomenon of pseudo-compact and so prone to leaks.



     2.3 The valve body and cause of the leakage



     The main reason is due to the leakage valve valve production process caused by casting or forging defects, such as trachoma, pores, cracks, etc., and flushing fluid medium and gas valve leak caused by corrosion is also a common factor.

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c.Metal sealing butterfly valve in the application of low temperature devices introduced

I. Low-temperature disc valve sealing performance requirements:



Low-temperature valve leakage, there are two main reasons, the first internal leakage; second is leakage.



Second, valve body, stem bushing design requirements:



1) low-temperature structure of the shape of the valve housing. Material selection of the correctness of the reliable work of the normal valve has an extremely important significance. And the structural characteristics of butterfly valves, gate valve, compared not only to avoid the result of irregular shape, uneven wall thickness of the shell, resulting in low temperature shrinkage, thermal stress caused by deformation, and because small butterfly , about the basic body shape is known, thus the small heat capacity; to cold is also a small amount of consumption; the shape of rules to facilitate cooling of the valve security measures. DD363H such as newly developed disc-type valve in the valve in order to ensure reliable low temperature use, in full accordance with the specificity of low-temperature valve design and manufacturing, such as: choice of shell material with a cubic lattice, such as austenitic stainless steel of 1Cr18Ni9Ti.



2) the choice of stem Bushing: According to users, some of them are running low-temperature valves, valve parts rotational viscosity occurred in occlusion occurred from time to time, the main reasons are: material selection matching unreasonable, to stay in the cold space too small, as well as precision machining and other reasons.



In the development of low-temperature valve, and take a series of measures to prevent the above phenomenon. For example: we stem the upper and lower bushing friction coefficient with selected small and self-lubricating properties of the SF-1 composite bearings, so that low temperature can be applied to the special needs of some of the valve.



Butterfly valve with metal seal type is characterized by some general do not have valves. In particular, flow resistance is small, sealed reliable, rapid headstock, and long life. The Company developed three eccentric butterfly valve seal sealing metal edge from the elastic deformation to achieve sealing ring, which media do not need to use force, it can be sealed with a two-way. According to some of the characteristics of butterfly valves will be more people paying attention to. The future there will be more applied to the butterfly valve in the low-temperature equipment.

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Frequently Asked Questions the use of valves

1, Why is the small two-seater valve opening easy oscillation work?

     On single-core, when the medium is the open-type flow, the valve is stable; when the media is closed-type flow, the valve margin of stability. There are two two-seater valve spool, the spool in a closed-flow, open the valve core in the flow, so that work in a small opening, the flow-type closure, it is easy to cause the spool valve vibration, this is the two-seat valve can not be used for a small opening located on the reasons.

2, why can not double-sealing valve used as a shut-off valve?

     The advantages of two-seater spool valve is a balanced structure of power, allowing large pressure difference, which highlighted the shortcomings of the two sealing surface can not be a good contact at the same time, resulting in large leak. If it is artificial, forced to cut off the occasion for the apparently poor results, even if it made a number of improvements (such as dual-sealed valve sleeve), is also undesirable.

3, what straight trip valve prevent poor performance, angle stop valve good trip?

     Straight vertical stroke spool valve to reduce expenses, while the level of medium is flowing into the outflow valve cavity flow is bound to turn back Shui, the flow valve so that the road has become very complex (such as the shape of inverted "S" type). In this way, there are many dead zones, the precipitation for the media to provide a space for the long run, causing congestion. Trip valve angle is the direction of cutting the level of direction, flowing into the medium level, the level of outflow, easy to clean medium away, at the same time the road is simple, medium and few precipitation space, so stop angle valve performance itinerary.

4, why the valve stem straight trip smaller?

     It involves a simple mechanical principle: sliding friction, and rolling friction small. Trip valve stem straight up and down movements, fill a little bit pressed, it will stem a very tight package, have a greater backlash. To this end, the design of very small stem, commonly used fillers and friction coefficient of PTFE packing small in order to reduce the backlash, but the resulting problem is to send small stem, is easy to turn, fill a short life expectancy. Resolve this problem, the best way is to use valve stem brigade, that is, angle valve type of trip, its itinerary straight stem stem rough than 2 ~ 3 times, and the choice of life-long graphite packing, stem stiffness good, long life packing, the friction torque but small, back to the small difference.

5, why the angle of the cut off valve trip pressure category larger?

     Class trip angle valve cut off the larger pressure difference is due to media in the valve spool or on the board have a rotation axis of the joint torque generated by a very small, so that it can bear a greater pressure differential.

6, why the use of desalination water medium rubber lining butterfly valve, valve衬氟short life?

     Water desalination medium containing low concentration of acid or alkali, they have a greater corrosion resistance rubber. Corrosion performance of the rubber for the expansion of the aging, low-intensity, with rubber lining of the butterfly valve, valve results are poor, its substance is the corrosion caused by rubber intolerance. After the valve rubber lining for corrosion resistance improvement衬氟good valve, but valve衬氟not stand up to the diaphragm also be folded up and down folding broken, resulting in mechanical damage, shorten the life of valve. The best way now is to deal with special ball valve water, it can be used to 5 to 8 years.

7, why cut off the valve should be sealed a hard choice?

     Leakage requirements of the lower shut-off valve, soft seal the leak valve is the lowest cut off effect is good, but not wear and poor reliability. Leakage from the small, sealed double standards and reliable, the soft sealing off sealing off on the hardware as well. Such as super-light full-function valve, sealing and protection of reactor are wear-resistant alloys, high reliability and the leakage rate of 10-7, has been able to meet the requirements of shut-off valve.

8, why replace the single sleeve valve, valve seat does not do?

     60's come out of the sleeve valve, 70 large-scale use at home and abroad during the 80's the introduction of the petrochemical plant in the sleeve valve larger percentage of that time, many people believe that the sleeve valve can be replaced by a single, two-seat valve become the second-generation products. Now, is not the case, single-seat valves, seat valves, sleeve valves have been the use of the same. This is because the sleeve valve is only the form of improved savings, stability and the maintenance of good in the single-seat valve, but it is the weight and prevent leakage targets with single-, two-seat valve in line, how can it replace the single-, two-seat valve it? Therefore, the only common use.

9, Why is that selection is more important than the calculation?

     Comparison of calculation and selection, the selection should be much more important, is much more complicated. Because only a simple calculation formula, which itself does not lie in the accuracy of the formula, but rather given by the accuracy of the process parameters. Selection of content related to more, a little careless mistake will lead to selection of properly, not only of human, material and financial resources of the waste, and the results are not satisfactory, the use of bringing a number of issues, such as reliability, life, running quality.

10, why in the pneumatic piston valve in the use of implementing agencies will be more and more?

     The pneumatic valve, the piston body can take full advantage of the implementation of gas pressure on the executive body size smaller than film, more thrust, piston O-ring in the film than reliable, so it will be the increasing use of more. valve ball valve gate valve check valve globe valve butterfly valve
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The working principle of the oxygen valve and its use

In the physical and chemical experiments, often use the oxygen, nitrogen, hydrogen, argon and other gases. These gases are generally stored in a dedicated high-pressure gas cylinders in. Through the use of gas pressure relief valve so that the necessary scope to experiment, and then, after fine-tune other control valve, so that the use of gas input system. The most commonly used pressure relief valve for the oxygen, or oxygen table.



1. The working principle of the oxygen pressure



The appearance of oxygen and pressure relief valve works.



High-pressure oxygen chamber pressure relief valve connected with the cylinder, low pressure chamber for gas exports, and to use the system. Table showing the value of high-pressure cylinders for the pressure of stored gas. Low table by adjusting the outlet pressure control screw.



Cylinders used to open the master switch, and then clockwise rotating low pressure regulator screw table to compress the main spring and transmission film, pad, and push-rod spring open the trap door. This high-pressure gas imports from high-pressure decompression chamber by cutting into the low pressure chamber, and by the export system to work. Turning adjustment screw to change the height of the trap door open in order to adjust the volume of high-pressure gas through the pressure to achieve the required value.



Are equipped with safety relief valve. It is a relief valve and the protection of the safe use of devices as well as reducing signal device failure. If, as a living doormat, valve damage, or due to other reasons, led to pressure to increase exports and to permit more than a certain value, the safety valve will automatically open the exhaust.



2. Reducing the use of oxygen



(1) according to different application requirements, there are many specifications of oxygen pressure. Imports are for the most part the highest pressure, the minimum inlet pressure of not less than 2.5 times the outlet pressure. Specifications of outlet pressure more generally, the maximum pressure for export.



(2) relief valve should be installed to determine whether the specifications of its connection with the cylinder and use the system in line connector. Relief valve used with the hemispherical cylinder connected by nuts tightened up so that they fully coincide. Therefore, in the use of the two hemispheres should be to maintain the smooth surface to ensure a good airtight effect. Pre-installation of high pressure gas can be used in addition to blowing dust. Can also be used when necessary, such as PTFE gasket materials.



(3) exposure to oxygen grease relief valve should be prohibited in order to avoid fire accidents.



(4) stop working when the relief valve should be put in the net more than gas, and then screw loose screw adjustment so as to avoid long-term pressure on deformation of elastic element.



(5) Reducing the impact of vibration should be avoided, not in contact with corrosive substances.



3. The other gas relief valve



Some gases, such as nitrogen, air, argon and other permanent gases, oxygen pressure relief valve can be used. But there are a number of gases, corrosive gases such as ammonia, etc., you need a dedicated valve. Common market, there are nitrogen, air, hydrogen, ammonia, acetylene, propane, steam and other special relief valve.



Reducing the use of these methods and points for attention with the oxygen valve is basically the same. However, it should be noted: a dedicated pressure relief valve generally not used for other gases. In order to prevent misuse, and some special pressure relief valve and the special connection between the cylinder mouth. For example, hydrogen and propane are used thread left teeth, also known as reverse-threaded, should pay special attention to the installation. ball valve Trunnion Mounted Ball Valve Floating Ball Valve Top Entry Ball Valve Three way ball valve V Type Ball Valve
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Process control valve should be how to choose (b)

2.2 Control Valve Selection of implementing agencies



2.2.1 consider the output power



No matter what kind of executive body type, the output power are used to overcome the effective load (mainly refers to the imbalance and the imbalance torque plus friction, sealing force, gravity force and so on). Therefore, in order to enable the valve to work with the implementing agencies to use to be able to generate sufficient output power to overcome all kinds of resistance, to ensure a high degree of sealing and the valve open.



Dual role for pneumatic, hydraulic, electric actuator, generally did not reset the spring. The size of force and its direction has nothing to do, therefore, to choose the key implementing agencies to ascertain the maximum output force and torque motor rotation. The role of the single executive body of the pneumatic, the output force and the opening of the valve, regulating valve on the emergence of the power will also affect the motion characteristics, it requires the opening of the regulating valve to establish equilibrium range.



2.2.2 Determination of the type of executing agency



Output force of the implementing agencies are identified, the use of environmental requirements according to process, select the appropriate enforcement agency. For the scene, where explosion-proof requirements, implementing agencies should use pneumatic and explosion-proof junction box for the type, can not choose the electric actuator. If there is no explosion-proof requirements, pneumatic, electric actuator can be selected, but to consider energy conservation should be the executing agency for electric choice. Executing agency for the liquid, its use as pneumatic and electric actuator extensive regulation accuracy but with high speed and smooth movement characteristics, therefore, in some cases, in order to achieve better regulation of the effect of liquid must be selected implementing agencies, such as power plants transparent machine speed regulation, the refinery's catalytic cracking unit reactor control temperature regulation.



3 The role of valve options



The role of regulating valve means only when the optional pneumatic before executing agency, and its executive body adopted the role of positive and negative role and valve combination of positive and negative role in the formation. There are four kinds of combinations that are (gas-off), both positive and negative (open air-type), in any case (open air-type), counter (air-off), formed through the combination of these four modes of control valve gas two open gas clearance. Regulating valve for the choice of the mode of action, mainly in three aspects to consider: a) Process of production safety; b) the characteristics of media; c) to ensure product quality, minimize economic losses.



Flow regulating valve 4, the choice of characteristics



Control valve flow characteristics of the media refers to the relative flow through the valve flow and the displacement (relative valve opening) the relationship between the ideal flow characteristics of the main straight, and the percentage (logarithmic), and soon to open, such as parabolic four kinds of , the ideal flow characteristics of commonly used only a straight line, such as the percentage (logarithmic), quickly open the three. Parabola and a straight line between the flow characteristics, such as the percentage between the percentage of the general characteristics can be used to replace and so on, and soon to open for the two main characteristics of regulation and control, and therefore the choice of control valve characteristics and is actually a straight line features, such as the percentage of flow choice.



Control valve flow characteristics through the choice of theoretical calculations, but the methods and equations is complex. At present, guidelines for the use of the experience of specific aspects from consideration: ① conditioning systems from the analysis of the regulation of quality and choice; ② piping from the process considered; ③ from the analysis of changes in load.



The choice of a good control valve flow characteristics can be determined in accordance with its flow characteristics of the valve spool of the shape and structure, but like valve, butterfly valve and so on, because of their structural characteristics, it is not possible to change the valve core with the surface shape to achieve flow characteristics needed, then, can be allocated by changing the valve positioner feedback form to achieve the cam. ball valve Trunnion Mounted Ball Valve Floating Ball Valve Top Entry Ball Valve Three way ball valve V Type Ball Valve
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Affect the safe operation of the factors regulating valve and Countermeasures

 In the higher degree of automation of chemical control system, regulating valve as the implementation of automatic adjustment system, the terminal device to receive control signals to achieve the regulation of chemical processes. It is directly related to the sensitivity of the action-conditioning systems quality. According to the site of about 70% of the actual statistics of the failures come from regulating valve. Therefore, routine maintenance review and analyze the impact the safe operation of control valve factors and countermeasures.

     Card blocking

     Valve recurring problem is that card blocked, often appear in the new transport system and the overhaul of investment put into operation in the initial stage, due to pipe welding slag, rust, etc. at the cutting mouth, oriented so that part of blockage caused by poor circulation media, or regulating valve repair in the tight packing, resulting in increased friction, leading to large-signal small-signal non-action motion overshoot phenomenon.

     Troubleshooting: You can quickly open, off-line or adjust the valve, vice, so that dirt from the Vice-line or adjust the valve was washed medium run. Another way to stem tube clamp tight, plus the signal pressure in the case, the positive and negative force rotating stem, so that spool flash card office. If it is not an increase of gas pressure to increase the drive power source has repeatedly moved up and down several times, you can solve the problem. Should the motion not, it would take the disintegration of treatment.

     Leakage

     Valve leakage, valve stem length of the discomfort. Air to open valve, stem long stem up (or down) the distance is not enough, resulting in gaps between the valve core and valve seat can not be full access, leading to lax customs and internal leakage. Similarly, gas off valve stem is too short, resulting in gaps between the valve core and valve seat can not be full access, leading to lax customs and internal leakage.

     Solution: should be shortened (or extended) regulating valve stem so that the length of the right valve so that it no longer internal leakage.

     Packing leakage

     Packing into stuffing after the axial pressure imposed by the gland. Because the plastic filler to produce a radial force, and close contact with the valve stem, but this contact is not very uniform. Some parts of the loose contact with some parts of the tight contact with, or even no contact at some parts. Regulating valve in the use process, the stem with the filling between the relative movement, this movement is called axial movement. The use of the process, with the high-temperature, high pressure and permeability of fluid medium strong, regulating valve packing leak letter is part of larger phenomena. Is mainly due to leakage caused by filler interface leakage, will appear for the textile and packing leakage (pressure medium along the filler-gap between the small outward leak). The interface between the stem and the packing leakage is due to the gradual attenuation of the contact pressure filler, filler causes such as their own aging, when the pressure medium will be along the contact between the filler and the valve stem outward leakage gap.

     Countermeasures: In order to facilitate the filler loading, in the stuffing to the top chamfer, in the stuffing box placed at the bottom of the smaller gap erosion-resistant metal protection ring (with the contact surface can not fill slope) in order to prevent the fill material was medium pressure introduced. Stuffing box packing contact with the ministries and part of the metal surface to be finished, in order to improve the surface finish and reduce packing wear and tear. Flexible graphite packing selected because of their good gas tightness, the friction is small, changes after long-term use of small, wear the burning of a small, maintenance easy, gland bolts re-tightened after the friction does not change, pressure and resistance heat well, is not within the medium erosion, with the stem and the stuffing does not occur within the contact with the metal pitting or corrosion. In this way, the effective protection of the valve stem seal stuffing to ensure the reliability of sealing packing and long-term.

     Valve core, valve leakage deformation

     Valve core, valve leakage was mainly caused by the production process control valve in the casting or forging defects can lead to corrosion strengthened. The corrosive medium through the fluid medium can also result in erosion control valve leakage. Erosion or corrosion mainly exists in the form of cavitation. When the corrosive medium through the valve, it will give rise to spool, valve seat materials, erosion and impact so that valve core, valve seat into an oval or other shape, as time goes on, leading to valve core, valve seat is not matching, there is clearance, Guan lax leak.

     Solution: The key to a good valve core, valve seat material selection customs, quality. Select corrosion-resistant materials, Ma points, trachoma and other defective products and resolutely removed. If the valve core, valve seat deformation is not serious, can grind through the fine sandpaper to remove traces, improve sealing finish to improve sealing performance. If serious damage, it should be re-replaced with new valves.

     Oscillation

     Control valve spring stiffness of inadequate control valve output signal instability could easily cause a drastic change in valve oscillation. Also that the election of the frequency of the system valve or pipe the same frequency, base severe vibration, so that control valve resulting vibrations. Selection of improper valve working in a small opening there is a violent flow resistance, velocity, pressure changes, when more than valve stiffness, stability deteriorated, severe oscillation.

     Solutions: As the oscillation are many reasons, so the concrete analysis of specific problems. A slight vibration vibration, can increase the stiffness to eliminate. Chooses to use the large stiffness of spring, use piston implementation structures. Pipeline, the base support by increasing the elimination of severe shock vibration interference; selected valve the same as the frequency and system frequency, then switch to a different structure of the valve; work in the small openings caused by the oscillation, it is improper selection of flow capacity of C values of selected large, Selection of capacity C must be re-circulation of the value of the smaller or using sub-process control valves, or Picture-regulating valve in order to overcome the work of a small opening.

     Valve Positioner Fault

     Ordinary locator using mechanical force balance principle, namely nozzle baffle technology, mainly in the following fault types:

     1) the use of mechanical force balance principle of work and its moving parts are more susceptible to temperature, vibration, resulting in control valve fluctuations;

     2) The nozzle shield technology, due to the nozzle hole is very small, prone to dust or clean gas source block is the locator does not work;

     3) Use of force balance principle, elasticity of the spring occurs in adverse changes in the scene, resulting in non-linear lead to the control valve decline in the quality.

     Smart Positioning is controlled by a microprocessor (cpu), A / D, D / A converter and other components, whose working principle and common Locator different. For a given value and actual value comparison of purely electric signal, is no longer a force balance. Therefore, to overcome the conventional force balance locator shortcomings. However, for emergency parking lot timely, such as emergency shut-off valves, emergency venting valve. These valves require stationary at a certain location, only an emergency occurs, it requires good movement. Prolonged stay in a location easy for the electric converter small-signal does not cause uncontrolled movements of hazardous situations. In addition, the valve position sensor for the potentiometer as a result of on-site, easy to change in resistance value caused by the small-signal non-action, large-signal full-hazards. Therefore, in order to ensure the reliability and intelligent positioning device availability, they must be frequently tested.

     By regulating valve failure cause analysis and take appropriate treatment, improved methods will greatly enhance the utilization of regulating valve to reduce instrument failure rate, the process technology to improve production efficiency and cost-effective and energy consumption all have an important role in reducing can effectively improve the quality of conditioning systems, thereby ensuring long-cycle production plants running. 

  ball valve Trunnion Mounted Ball Valve Floating Ball Valve Top Entry Ball Valve Three way ball valve V Type Ball Valve
We can offer more Knife Gate Valve Information.If you need us according your spcification to produce the Knife Gate Valve .
Need, please e-mail to valve401@gmail.com