Sunday, August 29, 2010

What is a Self-regulating valve

Self-regulating valve to rely on its own medium flowing through the valve pressure, temperature as an energy-driven valves work automatically and requires no external power supply and the secondary instrument. This Self-regulating valve are making use of valve output feedback signal (pressure, pressure, temperature) through the signal tube passed to the implementing agency-driven valve flap to change the valve opening, to regulate pressure, flow, temperature. This control valve is further divided into direct and indirect effects-action-type two kinds.

     Direct-acting type is also known as spring-loaded type, its structure and flexible components, such as springs, corrugated tube, corrugated tube temperature packs, using elastic force and the principle of balance between feedback signal.

     Indirect effects of type regulating valve, an increase of a command device (pilot valve) it played the role of the feedback signal amplification and then through the implementing agencies, driving the main valve valve valve movement to achieve the purpose of changing the valve opening.

     If the pressure regulator valve, the feedback signal is the valve outlet pressure, the introduction of the implementing agencies through the signal tube.

     If the flow control valve, valve outlet there is a plate (or other resistance devices) removed from the pressure plate at both ends of the signal to introduce the implementing agency.

     If it is the temperature control valve, valve's exports have temperature sensors (or warm pack) through the temperature sensor of the thermal expansion and contraction within the media-driven executive body. ball valve Trunnion Mounted Ball Valve Floating Ball Valve
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Wednesday, August 25, 2010

Common valve fault and the elimination of Method

Safety valve failure is mainly due to the design, manufacture, selection or improper use. These failures, if not promptly removed, it will affect valve efficiency and life, not even a security protection. Common faults and eliminate as follows:



(1) leak. In the device under normal operating pressure, valve flap and valve seat sealing surface between the degree of leakage of more than allowed. The reasons are: valve flap and valve seat sealing surface between the dirt. Wrench can be used to enhance the valve is open several times, the dirt washed out; sealing surface damage. Should be based on degree of injury, using grinding or after grinding method of turning to repair; stem bending, tilt lever with the fulcrum, or skewed, so that spool and the valve flap dislocation. Should be re-assembled or replaced; spring elastic lower or no flexibility. Should be taken to replace the spring, re-adjust the opening pressure of other measures.



(2) to the required pressure is not open. The reason for this result is the constant pressure are not allowed. Should re-adjust the amount of compression spring or a heavy hammer position; valve flap and valve seat stick. Should be placed manually on a regular basis on the safety valve for gas or turn on the water test; lever-type safety valve is stuck or heavy hammer, the lever is moved. Should re-adjust the position of the heavy hammer and to leverage campaign freely.



(3) less than the required pressure to open. Is mainly constant pressure are not allowed; spring decline in the aging stretch. Should be properly tightened screw to adjust or replace spring.



(4) The exhaust back pressure continues to rise. This is mainly due to the use of safety equipment, safety valve to vent emissions Xiaoping contribution, should be re-select the appropriate safety valve; stem rust midline errors or spring, so that valve flap can not be opened to the proper height, should be re-assembled stem or replace the spring; the exhaust pipe cut-off there is not enough, should be taken to comply with the safety area of the exhaust pipe emissions.



(5) The valve flap jump frequency or vibration. Was mainly due to large spring stiffness. Should be replaced by an appropriate spring stiffness; adjustment ring to adjust properly, so that the pressure is too high back seat. Should re-adjust the adjustment ring position; discharge piping resistance is too large, resulting in excessive emissions of back pressure. Should reduce the emission of piping resistance.



(6) The discharge does not return after the flap valve seat. This is mainly spring curved stem, valve installation position is not correct or stuck valve caused. Should be re-assembled. 

  

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Monday, August 23, 2010

Development of 200-inch ROPO Germany 5 m in diameter, the largest butterfly valve

 

July 7, 2008, the German company to produce ROPO and work through the company from top to bottom, 200-inch butterfly valve assembly qualified success. This valve is not only the success of the company so far the largest butterfly valve assembly qualified, is their biggest-ever production of valves, valve industry in China reached the most butterfly valve, the valve also marks the company's manufacturing has been on the a new stage, China is more of a major machinery and equipment has contributed to their own. Butterfly valve for the Russian oil export pipeline valve, the valve of about 60 tons weight.



     ROPO company in the manufacture of this large valve specification process, issued from the task, the close follow-up on and do all the technical, equipment related to preparations for testing the strict control of the Ministry of precision machining parts, while the manufacturing sector arrangements are equipped with the experience of workers in assembly, to ensure that the valve assembly requirements.

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Dynamic flow balance valve performance

 In the air-conditioning and heating system, water system, as energy transmission and distribution of water balance is very important. A balanced hydraulic system is to meet user needs, saving energy consumption basis.

     In the air-conditioning and heating systems, cold (hot)-borne transmission and distribution pipeline system from the closed to the consumers. For a well-designed systems, and all users at the end valve (electronic control valve, temperature control valve, etc.) is 100% opening should have access to the design of water, while the various users at the end of the opening control valve to change the when you can get the required flow again without disturbing each other. This water system is a hydraulic balancing system, otherwise unbalanced hydraulic systems, hydraulic imbalance also known as hydraulic imbalance.

     Hydraulic imbalance is generally divided into two kinds of static imbalance and dynamic imbalance. The so-called static disorder, also known as steady-state offset. The system, each user in the design of state, does not match the actual flow and design flow. This hydraulic imbalance is fundamental, if not addressed, the impact will remain. For constant flow systems, this imbalance can be static or dynamic balance valve balancing valve to solve, the difference is that the former need to use instruments to regulate, while the latter do not need to. The so-called dynamic disorder also known as the stability of the disorder. The system, some users of the water flow when the change (closed or adjustable), the resistance distribution will cause the system to change, leading to the flow of other users with the changes. This imbalance is random changes in hydraulic and dynamic. Static balance valve can not resolve this imbalance can only be resolved using dynamic balancing valve.

     For example: for the six floors of a building, without installation of dynamic flow balance valve, then the water system in actual operation, dynamically disorders. In the air-conditioning cooling season, the first ~ second floor of the room would be too cold, three ~ four comfortable rooms just to meet the design temperature of 5 ~ six layers of the room is too hot. On the contrary, in the heating season, the first ~ second floor of the room would be too hot, the three ~ four comfortable rooms just to meet the design temperature of 5 ~ six layers of the room is too cold. After the installation of dynamic flow balance valve, whether it is a ~ six-room all to use, or only some of the rooms in the use of air-conditioned, all rooms can meet the design temperature. 

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Saturday, August 21, 2010

Valve products to the market trends showing a five

Distribution on the valve market are based mainly on the construction project, the largest user of the valve is the petrochemical industry, power sector, metallurgy sector, the chemical industry and urban construction departments. The main application of the petrochemical industry API standard valve, the globe valve and check valve; the electricity sector with the main power plant using high temperature pressure valve, the cut-off valve, check valve and safety valve and water supply and drainage part of the low pressure valve butterfly valve, gate valve; the chemical industry mainly uses stainless steel valve, stop valve, check valve; metallurgical industry mainly uses low-voltage large-diameter butterfly valve, oxygen valve and ball valve oxygen; urban construction department used mainly low-pressure valve, such as urban water use of large diameter pipe major gateway valve, put the construction of the main floor, the use of the center line butterfly valve, the main city of heating metal sealed butterfly valve; pipeline mainly flat gate valve and ball valve; the pharmaceutical industry mainly uses stainless steel ball valve; the food industry mainly uses stainless steel ball valve and so on.



Valve products on the market trends, according to analysis, the main trends in the coming period as follows:



1. With the development of oil fields to the mainland and the transfer of offshore oil field, as well as the electric power industry from below 300,000 kilowatts of thermal power to more than 300,000 kilowatts of thermal power and hydropower and nuclear power development, and valve products should also be based on changes in the field of device applications change its properties and the corresponding parameters.



2. Urban systems generally use a large number of low-pressure valve, and to environmental protection and development of energy-saving, that is, by the use of low pressure over the last steel valve towards environment-friendly plastic valve, balance valve, metal sealed butterfly valve butterfly valve and seal the center line of transition . Oil and gas pipeline projects to the direction of development, which in turn requires a large amount of flat gate valve and ball valve.



3. The other side of energy development is energy conservation, so to see from the conservation of energy, the development of the steam trap to the sub-critical and supercritical parameters of the development of the high.



4. The construction of power plants to large-scale development, it required large-caliber and high-pressure safety valve and pressure relief valve, but also need fast hoist valve.



5. Need to complete the project, the supply valve by a single species to multiple species and the development of multi-specifications. A valve for the project, by a valve manufacturer to provide all of the trend is growing.

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Analysis of body materials and a variety of materials commonly used heat treatment (b)

Blank Body heat treatment process according to different materials are as follows:



1. Gray cast iron heat treatment.



In order to achieve different purposes, gray cast iron casting can be carried out in different heat treatment. Valve production of gray cast iron casting body parts, such as after the heat treatment process often chosen are: the elimination of casting thermal stress limitation and elimination of free cementite of high-temperature annealing. Thermal aging process is essential to work together. High temperature annealing only in the casting as a result of the chemical composition and casting cooling rate controlled, resulting in organizations that exist after casting cementite when the new-born to use it to replace the thermal aging.



2. Carbon steel heat treatment.



After the casting steel casting foundry with a large residual stress, and sometimes the organization of large steel castings, and even organizations overheat. Affect the dimensional stability of steel castings, to reduce the mechanical properties of steel and is not conducive to the conduct of cutting. In order to eliminate casting stress, refined organization, improve the mechanical properties and improved, such as machining, valve of carbon steel production body parts such as casting or after the regular choice of annealing normalizing + tempering processing.



3. Austenitic stainless acid-resistant steel-based heat-treatment.



Type austenitic stainless acid-resistant steel is easy to have a major flaw Intergranular corrosion of steel in general can be taken to impose certain measures to prevent heat-treated. Valve production type of austenitic stainless steel acid-resistant parts of the body such as the heat treatment process often selected were: solution heat treatment (quenching), the stability of the processing and cryogenic treatment.



4. Martensite heat-resistant steel-based heat treatment.



Martensite-type heat-resistant steel in the foundry should be promptly after the annealing, prevent the generation of cracks, and holding time should be sufficient annealing (usually 4 to 8 hours). Martensite-type heat-resistant steel annealed to remove stress, to carry out recrystallization, grain refinement, reduce stiffness, improve cutting performance and is ready to do a good job in the final heat treatment.



Martensite-type heat-resistant steel eventually normalizing + tempering heat treatment used to deal with.



5. High-quality carbon steel heat treatment.



Heat treatment of high-quality carbon steel to steel valve body 35, for example, steel valve body 35 to be normalizing after forging, heat treatment and its ultimate valve manufacturer in accordance with the provisions of technical documents in general to quenching and tempering treatment. 

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Gas cylinder valve working principle and use

    In physical chemistry experiments, often use the oxygen, nitrogen, hydrogen, argon and other gases. These gases are generally stored in a dedicated high-pressure gas cylinders in the. When used through the valve so that gas pressure down to test the required range, and then fine-tuning through the other control valves, so that gas entered the system. The most commonly used valve for the oxygen valve, referred to as oxygen table.

     1. Oxygen valve works

     The high-pressure oxygen chamber and the cylinder valve connected to low-pressure chamber for gas exports and access to use the system. Table showing the value of high-pressure storage of gas cylinder pressure. Low table outlet pressure adjustment screw can be controlled.

     When you first open the cylinder using the master switch, and then the table clockwise rotating low pressure regulator screw to compress the main spring and the transmission film, spring pads, and push-rod and open the trap door. This high-pressure gas imports from the high-pressure chamber through the throttle after decompression into the low-pressure chamber, and the exit leading to the working system. Turn adjustment screw to change the valve opening height, thus regulating the passage of high-pressure gases to achieve the required amount of pressure value.

     Valves are equipped with safety valve. It is to protect the valve and make the safe use of the device, is also a valve failure signal device. If, living doormat, valve damage, or due to other reasons, resulting in increased outlet pressure, and exceeds a certain permission on their own value, the valve will automatically open the exhaust.

     2. Oxygen valve to use

     (1) according to the different application requirements, oxygen valve has many specifications. Minimum inlet pressure of not less than 2.5 times the outlet pressure.

     (2) The installation of pressure reducing valve should be connected to determine whether the cylinder and the use of standard connector systems are consistent. Valve and the cylinder with hemispherical connections, tighten nut to rely on the two fit together well. Therefore, the use of the two hemispheres should be to maintain the smooth surface in order to ensure good gas-tight effect. Before installation can be high-pressure gas blowing addition to dust. When necessary, PTFE and other materials can also be used to make gaskets.

     (3) The oxygen valve should be forbidden contact with grease, so as to avoid fire accidents.

     (4) stop working when the valve should be placed in a net residual gas, and then loosen the adjustment screw so as to avoid long-term compressive deformation of elastic components.

     (5) The valve should be avoided shock vibration, can not be in contact with corrosive substances.

     3. Other Gas Regulator

     Some gases, such as nitrogen, air, argon gas and other permanent gases, oxygen valve can be used. But there are a number of gases such as ammonia and other corrosive gases, you need special valve. Common market are nitrogen, air, hydrogen, ammonia, acetylene, propane, water vapor and other special valves.

     The use of these valve methods and precautions with the oxygen valve basically the same. However, it should be noted: Private valve is generally not used for other gases. In order to prevent misuse, and some special valves and the cylinder using a special connection between the mouth. For example, hydrogen and propane are used thread left teeth, also known as reverse-threaded, the installation should be special attention. 

  

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Solenoid valve Some small sense

  1. Security: pay attention to security will lead to disaster

    1. Corrosive media: should use plastic solenoid valve and all stainless steel solenoid valve; for the strong corrosive medium must be selected isolated diaphragm. Cases of CD-F. Z3CF. Neutral medium, it should use copper alloy for the valve shell materials, electromagnetic valve, otherwise the shell valves are often chip off rust, especially the movements infrequent occasions. Ammonia with the valve can not use copper.

    2. Explosive environments: explosion-proof grade products must be selected accordingly, open-air installation or dust should be used more occasions, waterproof, dust-proof varieties.

    3. Solenoid valve Nominal pressure shall not exceed the maximum working pressure of pipe.

2. Applicability: Not applicable fee equal to money to buy materials, but also trouble

    1. Dielectric properties

    1.1 The quality of gas, liquid or mixed state were selected to different kinds of electromagnetic valve cases ZQDF for air, ZQDF-Y for liquid, ZQDF-2 (or -3) for the steam, otherwise easily cause malfunction. ZDF Series multi-function solenoid valve may be common in the air. Liquids. The best set, went out the state media, install the user no longer modal.

    1.2 Medium temperature products with different specifications, otherwise the coil will be burnt, seals aging, seriously affect the life of life.

    1.3 medium viscosity, usually in the 50cSt below. If it exceeds this value, diameter greater than 15mm Series multi-function solenoid valve with ZDF to make a special order. Diameter of less than 15mm solenoid valve provides a high viscosity.

    1.4 Cleanliness is not high when the media should be equipped with the electromagnetic valve before the filter backflushing valve, low pressure moving fashion can choose straight diaphragm solenoid valve, such as the CD-P.

    1.5 If the directional flow of media, and are not allowed back ZDF-N and ZQDF-N alone. You need to use two-way flow, please make a special request.

    1.6 Medium temperature should be chosen within the allowable range solenoid valve.

    2. Pipeline Parameters

    2.1 According to media flow requirements and pipe connection valve openings and model selection. For example, for a pipeline to the two channels to switch, the small diameter of the election CA5 and Z3F, medium or Chase Drive Please select ZDF-Z1 / 2. Another example is control of convergence of the two pipelines, please select ZDF-Z2 / 1 and so on.

    2.2 In accordance with the value of the selected flow rate and valve Kv DN, but also optional with the pipe diameter. Please note that some manufacturers are not marked with the Kv value, often less than the interface valve hole size diameter, must not covet low price and makes a botch.

    2.3 Working pressure above the minimum working pressure is available in the 0.04Mpa use indirect Pilot; minimum working pressure close to or less than zero must be selected direct-acting type or sub-step direct type.

    3. Environmental conditions

    3.1 environment, the maximum and minimum temperature should be chosen within the allowable range, if the need for ultra-poor special order made.

    3.2 environment, relative humidity is high and there are water droplets and rain and so on, to be elected water solenoid valve.

    3.3 environment, often have vibration, bumps and shocks should be elected special varieties such as occasion, such as marine solenoid valve.

    3.4 in a corrosive or explosive environments should be given priority in the use of security requirements under the optional corrosion-resistant.

    3.5 environmental space if limited, please use multi-function solenoid valve, because eliminating the need for a bypass and three manual valves, and easy online maintenance.

    4. Power Supply Conditions

    4.1 according to power supply types, were selected to AC and DC solenoid valves. Generally speaking, convenient access to AC power.

    4.2 Voltage specification with the best preferred AC220V.DC24V.

    4.3 AC power supply voltage fluctuations are usually chosen +% 10% .- 15%, DC to allow ±% 10 or so, should the ultra-poor, regulators should take measures or make special order requests.

    4.4 The choice should be based on rated power capacity and consumption of power. VA should be noted that the value of the exchange-start high, inadequate capacity should be preferred in the indirect-guided electromagnetic valve.

    5. Control accuracy

    5.1 Common solenoid valve is only opened, closed two locations in the control of high precision and parameters for a smooth when you use a number of solenoid valves; Z3CF three normal open solenoid valve, with Enlight, fully open and close the three kinds of traffic; ZDF -Z1 / 1 combination of multi-function solenoid valve has a fully open, wide open, small open, open all four kinds of traffic.

    5.2 Action Time: refers to connect or disconnect the electrical signal to the main valve movement completion time, it's patented multi-function solenoid valve can adjust the opening and closing time was not only to meet the control accuracy requirements, but also to prevent water hammer damage.

    5.3 leakage leakage given the sample values for common economic level, if too high, please make a special order.

Third, reliability: not reliable, would undermine the entire system

    1, working life, this is not included in the pilot project factory belonging to type pilot projects. In order to ensure quality, brand-name manufacturers should be regular elections.

    2, the working standard: sub-system of long-term, repeated short-term work system and the three kinds of short-term work system. For a long time only a short-term closure of the valve opening of the case, are advised to use normal open solenoid valve. Short-term work system used in large quantities when they can be used as a special order to reduce power consumption.

    3, the working frequency: Action frequency of requests is high, the structure should be preferred direct drive type solenoid valve, power exchange should be preferred.

    4, operating reliability: Well, strictly speaking to the pilot solenoid valve has not yet formally included in our professional standards, to ensure the quality of the brand-name manufacturers should be regular elections. Some occasions the number of actions are not many, but very high reliability requirements, such as fire, emergency protection, must not be taken lightly. Particularly important, should be used in conjunction to take two pairs of insurance.

4. Economy: Not the economy is on the money, energy and even a waste of life

    It is one of the chosen scale, but it must be in a safe, suitable and reliable based on the economy. Economy is not only the product price, but also to give priority to their functions and quality, as well as the installation and maintenance, and other accessories required for the cost. More importantly, a solenoid valve in the whole production line automatic control system, as well as the share of costs are minimal, if the election just for the sake of small cheap and wrong, the damage is enormous.

    In short, the economy not just price, but rather from the product's performance and price the cost price for the comprehensive assessment. 

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Valve leakage and sealing technology

Valve leakage in life, the production is widespread, ranging from lead to waste, or dangerous to life, such as the water valve leakage, the case can lead to serious consequences from occurring, such as the chemical industry's toxic, hazardous, flammable, easy to mediated nature of the explosion and leakage of corrosive and so on, a serious threat to personal safety, property safety and environmental pollution accidents. External rotation on a drive to open and close the valve are designed to have a seal not only used in the Han-Zhong Zhuang fill a certain amount of filler on the seals, as well as achieve the sealing effect, but the situation on how to seal it? The valve is a valve packing leak and the most prone to leakage faults in the site of one, but the reason there are basically two reasons.

     1, packing reasons.

     Fill is now mainly used are:

     1. Asbestos, due to the existence of asbestos materials, corrosive chloride ions on the stem, while asbestos, carcinogenic substances harmful to human health, the state has taken on the part of products banned or less use;

     2. Synthetic resins and synthetic fibers category, and some in the use of such products is subject to restrictions, such as the use of pure PTFE temperature must be ≤ 150 ℃, filled PTFE ≤ 250 ℃, PTFE particles packing compensation performance worse, it only applies to low-pressure valves, PTFE fibers, carbon fiber, or both mixed filler, and the price is too high, the negative extension;

     3. Expanded graphite, the electrochemical corrosion will be severe.

     Second, the amount of a corrosion problem reasons.

     Corrosion are:

     1. Stem natural oxidation corrosion, due to valve stem packing at the table being oxidized to produce four oxidation of three iron (rust), after falling, resulting in stem thinning, caused by leakage;

     2. Asbestos packing leakage caused by corrosion of chloride ions;

     3. Graphite packing pairs of stainless steel corrosion;

     4. Media on the stem of the corrosion and so on. 

  

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Than the infinitely adjustable control valve

    In 1958 designed the first RHWELKER Mr. Xiang Pise only control valve in order to meet the gas industry to the needs of low-noise multi-purpose, such Xiang Pise-type control valve of universal access to worldwide recognition. Then successively made many improvements to become today's WELKER JET control valve. Features: absolute turn-off, large soft sealing surface, even in the face welding slag, relatively large particles can also shut down tight. Minimum flow is absolutely zero.

    Some of the main valve can be individually connected as a direct-action can also be accompanied by indirect effects mediated valve into a style, can also be manipulated by pneumatic control.

    The main valve structure: it and the rubber tube valve principle of folders on the contrary, there is a streamlined channel of hollow rubber plug in the middle of the hollow rubber plug there are hydraulic medium, when the hydraulic medium pressure increases, the rubber plug expansion of the annular channel area is smaller, played the role of closure, medium pressure continue to rise, the rubber plug can be completely enclosed channels. Large diaphragm and the valve stem is composed of gas - liquid pressurization device, the deformation of the rubber plug on stress. Large diaphragm control valve is driven by the export of feedback, with the signal pipe connection. 

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Thursday, August 19, 2010

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

With the rapid development of industrial technology of the valve industry has more stringent requirements, particularly for low-temperature dielectric used in the butterfly valve, in addition to the general valve to meet the performance, it is more important is the state at low temperatures the reliability of the valve seal under the action of low-temperature flexibility, as well as some other special valve requirements. With the rapid development of industrial technology of the valve industry has more stringent requirements, particularly for low-temperature dielectric used in the butterfly, in addition to the general valve to meet the performance, it is more important is the state at low temperatures the reliability of the valve seal under the action of low-temperature flexibility, as well as some other special valve requirements.



As everyone knows, the butterfly valve has a compact structure, small size, light weight the same pressure, the same path of the valve compared to reduce 40% ~ 50%) of small fluid resistance, a series of advantages such as rapid headstock. However, in some low-temperature devices such as day of liquefied fuel equipment, air separation equipment, and pressure swing adsorption equipment used in the chemical industry more than 80% of the valve is shut-off valves, or valve, the use of a small number of butterfly valves. Analysis of its causes have been mainly in low-temperature metal sealed butterfly valve sealing performance under the adverse situation, and other unreasonable due to structural causes, such as medium leakage and leakage, severely affected the safety of these low-temperature equipment and the normal operation, can not meet the low-temperature equipment.



According to the continuous development of low temperature devices, the requirements of the valve on the low-temperature growing, to meet the needs of the development of a market economy, metal sealed butterfly valve on structural improvements in the development of a pure three-eccentric metal high sealing performance of Butterfly valve (Figure 1, has been declared national patent) is the high temperature regardless of medium or low temperature can meet their needs. Is combined with its structural characteristics, low temperature performance for only a brief introduction.

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Typical fault-type pilot relief valve What? How to exclude?

With the construction machinery hydraulic system to move in the direction of high pressure and high pressure, pilot-type relief valve is widely used in construction machinery hydraulic system in the control of asphalt. In use in practice, in order to maximize its effectiveness, protection control system, accurate and timely diagnosis, excluding pilot-type relief valve failure is the key component.



1, out of control, so that the host does not move



Pilot-type relief valve failure, will cause the host can not move. According to the phenomenon, analysis of the reasons are: the pilot valve spool spring break; damping hole plug; pilot valve sealing valve port bad; main spool choked to death and so on. The corresponding exclusion measures are: replacement of broken or in the office plus flat pad for emergency use; clean dredge; grind the asphalt, or open circuit to emergency use; grinding, cleaning.



2, limit voltage instability



Pilot-type pressure relief valve limits instability, manifested as low or high pressure hydraulic system, hydraulic actuator action unable or pipeline, pump, valve burst.



Cause of this failure for two reasons: the pressure to adjust himself; pilot valve spool spring bending or soften; oil too dirty or poor oil flow. The corresponding exclusion measures are: re-adjustment; correction, plus pad, or replaced; replacement, cleaning. Wear-resistant electrode



Limited pilot-type pressure relief valve for the gradual onset unstable failure, more than an hour more in reserve Motorcycle engineering machinery; pilot type relief valve failure as a sudden failure, often seen in the reserve motor works fewer hours machinery. Finished after a fault in the exclusion shall be defined by the machine of the system's pressure on the pilot-type pressure relief valve controls to re-adjust.

 

 

 

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Valve developed technology ideas

 


   Forged Steel Globe Valve   enterprises attach great importance to development of new products. It should be noted that the development of China's valve industry today, although the discrepancy with the international advanced level, but has gone beyond simply be absorbed phase. To seek ways to further develop the technology, it should be the analysis of advanced foreign products, but also, from a deeper level, the valve on the trend of technological development and product development direction of comprehensive analysis and thinking, efforts to develop new products with independent intellectual property rights .

Usually the main consideration in product design is its texture, structure, mechanical strength, work performance, life and other factors, in evaluating the pros and cons of the Cast Steel Globe Valve  , the general also use these targets. With the development of the times and social progress, people-oriented mindset and concepts have infiltrated all areas of social life, from the housing, cars, computers, cell phones, clothing, and a variety of public facilities can clearly feel this change, them from the safety, comfort, energy saving, environmental protection, new and beautiful, and many other aspects in every detail, both nuanced account of the consumer experience, reflecting on the people's love. Clearly, the human design should not be limited to the scope of daily consumer goods,  Y Pattern Globe Valve  , as a TV towers, widely used in industry, agriculture, national defense, and with people closely related to their daily working life of mechanical products, it can not always is confined to the traditional design concepts and design methods, but should explore new ideas and inject new ideas.

Our analysis of foreign advanced products, apart from the technical performance indicators, will be noted that its beautiful shape, structure compact, intracavity clean and elegant details. For example, in order to prevent secondary pollution, even the sewage valve does not use asbestos packing and gasket sealing. Another example is in order to avoid the operator's hands are scratched, the flange connecting bolts are processed into end of the first arc, etc., these specific differences in the details, should provoke us to deeper thought: why does it want to do this? How it think of doing this? conclusions can not be attributed to human-oriented design concept up, from this level up understanding, it will make our product design is no longer stay in the first phase of a simple, but from an ergonomic point of view, from a more secure, reliable, energy saving, environmental protection, clean production, operating comfort and convenience, easy disassembly and maintenance to study many aspects of thinking, to give the  Bellow Sealed Globe Valve   the traditional products with a new concept and image, forming their own characteristics.


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Tuesday, August 17, 2010

Inverted bucket type steam traps

Inverted bucket steam trap is a mechanical-type steam trap, one of the most solid of the trap, and its advantages are: afraid of water hammer, can be a continuous row of non-condensing gas, dirt performance is good; the maximum back pressure ≤ 80%, all inner parts are stainless steel, wear-resistant, anti-corrosion; spherical valve core and valve seat is a line of contact, good sealing performance and long service life; intermittent drainage and continuous drainage, can be ranked near the saturation temperature of condensed water, so that heating equipment to achieve the best good work efficiency. Inverted bucket steam traps in the water seal of the valve seat under the protection of working steam leak-free living, energy-saving effect is good.

     It is suitable for petroleum, chemical, printing, paper making, pharmaceutical and other industrial heating equipment, steam and steam vapor resistance of the drainage pipe network.

     Inverted bucket type steam trap is the use of condensed water and steam density difference between the working principle, the internal structure is connected by a lever system, inverted bucket, to overcome the pressure switch inverted bucket type steam trap is an inverted bucket inside for the level-sensitive parts, inverted bucket openings down. Device just starting when the air inside a pipe and low-temperature condensate, this time the whole trap open, air and cold condensate discharge quickly, installations quickly raise the temperature. When the steam into the inverted bucket, the inverted bucket generate upward buoyancy, inverted bucket link lever driven valve heart valve is closed. Opening a bucket down a hole can be automatically scheduled air, when a part of the steam discharged from the holes, and the other part of the condensation of water vapor generation, inverted bucket loss of buoyancy to the sink, pour bucket valve connecting the heart, opening the valve lever drive. When the steam re-entering the reversing bucket, the valve then closed, circular work, intermittent drainage.

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Valve Maintenance and Maintenance

 Pre-production in the welding of the Swing Check Valve   before and after the commissioning of the professional conservation work for the valve to serve production operations play a crucial role in the proper and orderly and effective conservation and maintenance will protect the valve, the valve to function properly and extend valve life.  Dashpot Check Valve, Slow Close Check Valve   conservation appears to be simple, does not. Work, often neglected aspect.

      First, the valve greasing, it is often overlooked issue of injection fat content. Note grease gun refueling, the operator selection of valves and injection mode coupling grease was conducted after the greasing operation. There are two kinds of situation: on the one hand greasing greasing less inadequate sealing surface and accelerated wear and tear due to lack of lubricant. Note the other hand, excessive fat, resulting in waste. Is no basis for the valve type of categories for different valve sealing capacity of precise calculations. Can be calculated Forged Steel Check Valve   size and type of sealing capacity, and then inject the right amount of grease and reasonable.

                       

      Second, the valve greasing, often ignore the stress. In the greasing operation, the injection pressure grease trough was changed regularly. The pressure is too low, seal leakage or failure, the pressure is too high, fat injection port plug, seal hardening or within the lipid with the valve seal  Pressure Sealing Swing Check Valve   plate Hugging. Typically, grease injection pressure is too low, the injection of grease into the valve chamber at the bottom of many, generally occurs in a small valve. The fat injection pressure is too high, on the one hand fat injection nozzle check and if so, grease hole blocking satisfied that the circumstances be replaced; the other hand, lipid hardening, to use the cleaning fluid, repeated failure to soften the seal fat, and inject new grease replacement . In addition, the seal type and sealing materials, also affect the grease injection pressure, the different forms have different sealing grease injection pressure, generally hard-sealing injection pressure is higher than the soft sealing grease.

                       

      Third, the valve greasing, the attention to the switch places the valve problem. Valve conservation in general are in the open position when the state of special circumstances, choose to close maintenance. Also should not be any other valve to open a bit punished. Valve in the conservation time must be turned off to ensure that grease seal along the seal is full of trenches. In the open position, sealing grease directly fall into the flow channel or valve cavity, resulting in waste.

                       

      Fourth, the valve greasing, often ignore the effect of injection fat problem. Greasing operation, the pressure, injection fat content, the switch position are normal. However, in order to ensure that the valve greasing effect, and sometimes need to open or close the valve, for lubrication checks to confirm the surface of the valve gate valve ball or even lubrication.

                       

      Fifth, note grease must pay attention to sewage and wire blocking the pressure relief valve problem. Valve pressure test, sealed valve chamber cavity gas and water due to environmental temperature and the step-up, when to conduct the sewage grease injection pressure relief in order to facilitate the smooth progress of the work of greasing. After injection grease seal cavity of air and moisture to be fully replaced them. Time to vent off valve cavity pressure, but also protects the use of safety valves. After greasing, be sure to tighten the wire blocking drainage and pressure relief to prevent accidents from happening.

                       

      Sixth, note grease must pay attention to even out the fat problem. Note the normal fat, the fat from the injection port nearest hole, first-out fat out of fat, then to low, and finally a high point, successive out the fat. If you do not follow the law, or no fat, prove the existence of congestion in a timely manner Kiyomichi treatment.

                       

      Seventh, note that even the observation of grease and seals the valve seat diameter flush the problem. For example, ball valve, if there is to open up the interference can be adjusted to the inside to open up stopper, confirmed after the lock straight path. Adjust the limit is not only the pursuit of open or closed one location, to be whole. If you open up flush, Guan is not in place, will cause the valve off lax. Similarly, adjust the customs are in place, we should also consider to open up accordingly. To ensure that the right-angle valve stroke.

Eighth, greasing, be sure a good seal grease injection port. To avoid impurities to enter the mouth or injection fat lipid oxidation, rust-proof seal to smear grease to prevent rust. In order to apply the next operation.

                     

      9th, note grease, they should also consider the future delivery of oil in order to treat specific issues. In view of the different quality of diesel and petrol should be considered the ability of gasoline erosion and decomposition. Valve operation at a later encountered when operating gasoline segment replenish grease to prevent wear and tear from happening.

                       

      Tenth, greasing, do not ignore the stem parts of the greasing. Parts of a sliding sleeve valve shaft or packing, but also the need to maintain lubrication to reduce friction during operation, if they can not ensure that the lubricant, then the electric operation, increased torque, wear and tear parts, manual operation switches effortlessly.

                       

      11th, some marked with arrows on the valve body, if not accompanied by English FIOW writing, for the sealing seat role in the direction of the flow of information not as media, since the vent valve in the opposite direction. Under normal circumstances, two-seater with a two-way flow valve seal.

                       

      12th, Butterfly Swing Check Valve  maintenance, also pay attention to the first and the transmission of electric water problems. In particular, infiltration of rain during the rainy season. First, institutions or shaft sleeve make transmission rust, and second, to freeze in winter. Caused by electrical valve operation torque is too large, damage to transmission components will protect the motor no-load or super-jump torque electric operation can not be achieved. Transmission component damage, manual operation is also impossible. In the ultra-torque protection action, the manual operation is also unable to switch, such as the forced operation, the damaged parts within the alloy.

                       

      To sum up, Double Plate wafer type Check Valve   maintenance is a science, its results can not see or touched. Truly scientific attitude in order to make the valve maintenance work to achieve the desired effect and application purposes.


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Sunday, August 15, 2010

Enhance the research and development capabilities to ensure business degree valve Wenzhou crisis

From the first two months of 2009 the situation, the financial crisis on the valve industry in Wenzhou, the effect of deepening trend, some small and medium enterprises is likely to close down, how to deal with the crisis of survival, is the industry's enterprises face a common problem.



     Wenzhou ball valve production and marketing enterprises better last year, but the situation in the first two months of this year, bad, and the financial crisis to the valve industry in Wenzhou is to deepen the impact.



     "Wenzhou gate valve key state enterprises to pay attention to engineering, research and development applicable to a number of nuclear power, oil and gas products and other aspects of the pump." March 29 in order to "address the financial crisis" as the theme of the valve industry development strategy seminar in Wenzhou City, Zhejiang Province. Chief Engineer of China Machinery Industry Federation Sui foreshore at the seminar for business ideas Wenzhou globe valve.



     Impact is steadily deepening



     According to statistics, in 2008 in Yongjia County of Wenzhou City in Zhejiang Province completed a total industrial output value and the associated pump 16.6 billion, an increase of 28%, paid 688 million yuan revenue, an increase of 33%, check valve exports 267 million U.S. dollars, 061 million U.S. dollars export pump , these two indicators Wenzhou exports account for more than 60%.



     "From last year's statistics, the enterprises in Wenzhou valve production and marketing situation is relatively good, but the first two months of this year can not be optimistic about the situation, the financial crisis to the valve industry in Wenzhou City, the impact is steadily deepening . "Yongjia Wenzhou Valve Association, chairman of Sun Group, said Sun Ye occasion.



     He analyzed that the international financial crisis to the whole of the butterfly valve industry in Wenzhou impact mainly in the following major areas:



     First, the enterprises, especially small and medium-sized orders of orders has declined markedly. Valve Wenzhou enterprises in late October last year to begin to feel the financial impact of the crisis, by the beginning of this year, this influence more apparent, with the exception of ultra-tat, Founder of individual enterprises, such as has not been affected, the vast majority of enterprises are feeling up.

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Characteristics of hydraulic control valves, repair and maintenance

Hydraulic control valve is pressure-controlled valves, hydraulic control valves from a main valve and its attached catheter needle � � � Introduction Ball valves and pressure gauges and other components. � Function in accordance with the purpose and the use of different sites can be turned into a remote control relief valve floating ball valve � � � Slow Close Check Valve Flow Control Valve pressure relief valve � � electric hydraulic control valves, control valves, pumps and so on.



Hydraulic control valves to be installed before the filter, and should facilitate the requirements of the sewage.



Hydraulic control valve is a type of water body from the run without additional lubrication oil, the main valve in the event of damaged parts, please follow the instructions to demolition. (Note: with valve damage goods for general consumption and the mid-ring diaphragm, little damage other internal parts)



1. First valve before and after the end of the main valve to close.



2. The main valve cover screws loose connector piping, pressure relief valve.



3. All the screws removed, including the need to control the line of the brass nut.



4. Check valve cover and spring.



5. The shaft core, diaphragm, piston, etc. removed and not damage patch.



6. All these things will be removed after the patch and check whether the mid-ring damage; If there is no damage on its own again Do not fight its internal parts.



7. If patch or mid-ring is damaged, please axle nut loose on the core, gradually break down or the patch-rings, out again after the patch or a new mid-ring.



8. A detailed view of internal main valve seat, such as whether the core axis is damaged, if other objects in the main valve to clean up the internal.



9. In accordance with the reverse is the order of replacement parts will be installed combination of the main valve, the valve can not pay attention to the phenomenon of resistance cards. 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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Heating valves commonly used in engineering works What is this?

Many different types of valves, using a wide range. Sometimes it is in the pipeline is the main device for control purposes; Sometimes it is a secondary device, play a supporting role. If used improperly, we will have "run the risk, dripping, and drain" phenomenon, light those affecting the production, in serious cases lead to accidents. Therefore, understanding and correct use of the valve is a very important issue.



In the heating system, use the valve there are many. Such as gate valve, globe valve, ball valve, butterfly valve, check valve, safety valve, regulating valve, balance valve, Self-balancing valve and so on. The following elaborate.



Valve



Also known as gate valve, gate valve, is widely used as a valve.



How it works: gate valve seat sealing surface with a high degree of sealing surface clean, smooth, consistent, processed into a fit, tight seal pair. Gate through the upper valve stem put down pressure on the media to form turn-on and turn-off. It is played in the pipeline shutdown role.



Benefits: fluid resistance is small; full-time sealing surface from erosion; can be a two-way flow of media use, there is no direction; strong and durable; is not only suitable for small valves, and can be bigger valves.



Disadvantages: high large; open and close a long time; heavy; repair is difficult; if it is large-diameter valve, manual operation is relatively more laborious.



Valve stem according to the different distinct rod and dark rod; by gate construct different sub-parallel and wedge-type; there is a single gate, Shuangzha divided board. Heating engineering, commonly used in the Ming-style single-pole wedge gate valve (Z41H-16C) and dark pole wedge single-gate valve (Z45T-10), the former station installed on the primary side of heat, which is loaded thermal stations in the secondary side. It generally play two roles: as a master switch from the role; as an auxiliary equipment for maintenance before and after the main device used.



Valve installation, not to hand wheel in a horizontal line below (flip), otherwise it would be medium in the long-term retention in the valve cover, easy to stem erosion. In the heat supply project, the gate was once the main force of the valve. Now, with the widespread adoption of butterfly valves, gate valve butterfly valve has been replaced.



Valve



Is also widely used as a valve. General caliber 100mm below. It works closely with the gate, but shut down parts (flap valve) the valve seat along the center line of movement. It is played in the pipeline shutdown, and may regulate flow of crude.



Advantages: create easy, easy maintenance, strong and durable.



Disadvantages: only allows one-way media flow direction when installing. Flow resistance big, bad seal.



Points according to different structures of straight-through type, rectangular type, DC type, balanced. Projects generally used straight-through flange (J41H) and internal thread straight through processing (J11H). Directional valve can not be under the anti-. We should not down-an.



In our production, life, in the past used straight-through processing, small-diameter cut-off valve, ball valve is now gradually being replaced.



Ball



Compared with gate valve, globe valve, ball valve is a kind of new, increasingly widely used valve. It works are: valve core cavity for a ball pass through the control spool valve stem for 90 ° rotation, so that the valve flow or occlusion. It is played in the pipeline shutdown role.



Benefits: In addition to a gate valve, globe valve advantages, there are small, sealed good (zero leakage), the advantages of easy to operate. Currently in the petrochemical, electric power, nuclear power, aviation and aerospace sectors such as widely used.



Disadvantages: repairs difficult.



Valve has two forms: floating ball and fixed ball type. In the heating project, a number of key positions, such as the important branch of the then population of thermal stations, DN250 below, often imported ball. Domestic ball with a different structure: Domestic valve in the valve body is generally two type, 3 type, flange connection;, while import valve in the valve body are one type, welded connections, less the point of failure. It is the Nordic country of origin, such as Finland, Denmark, heating technology, the more developed countries. Such as Finland, NAVAL, VEXVE, Denmark DAFOSS so. Because of its excellent sealing and operating reliability, long popular users of all ages. No directional valve can be installed at any angle. The level of welding ball valve installation, the valve must be open, to avoid the welding of the EDM hurt ball surface; When the vertical pipe installed, if the welding on the interface, the valve must be opened, if soldering the next interface, the valve must be closed in order to avoid valve internally heat burns.



Butterfly



In the heating system, is currently the most widely used, type is also up to a valve.



How it works: valve flap is a disc, through the stem rotation, valve flap in the seat for 90 ℃ within the rotation, to achieve the valve switch. It is played in the pipeline shutdown role.



May regulate traffic.



Advantages: simple structure, is lightweight, easy to operate and good sealing.



Disadvantages: full-time, valve plate (seal) by the media erosion.



In the heating project, there are three eccentric butterfly valves used metal sealing butterfly valve, rubber soft sealing butterfly valve.



Three eccentricity metal sealing butterfly valve



The so-called "three eccentric" refers to the valve shaft, valve plate in the relative position of the valve within the offset. Is a common eccentric butterfly valve, that valve shaft centerline and the centerline of the sealing surface (valve plate centerline) deviation; high performance coupled with an eccentric, or valve shaft centerline and the centerline of the valve (pipe centerline) deviation; double eccentric aim is to make the valve wide open to 20 °, after sealing off between the vice so as to reduce friction (cam effect). Three eccentric butterfly valve in the above-mentioned pairs of eccentricity to add on the basis of a unique eccentric - inclined cone, that is, valve plate offset (vertical pipe sealing surface with a tilt angle). This allows the valve in the 90 ° travel range are completely divorced from Sealing not only strengthened the cam effect, but also completely eliminates friction; the same time, the valve is closed, when the seal pair gradually closed, have a "wedge effect" in order to the minimum torque to achieve the most rigorous off.



The so-called "metal seal" refers to the valve seat, ring of wear resistant, corrosion-resistant, high-quality high-temperature alloys; the same time, seal with the valve seat in order to avoid head-on, designed to be flexible between the sealing contact with the Deputy that the formation of "flexible metal seal "to ensure that off too tight, open without friction. With the "three eccentric" structure, and then supplemented with "flexible metal seal" so that the valve operation of lightweight, durable and a good seal.



Three eccentricity metal sealing butterfly valve usually used in the heating system on the trunk and main branches. DN300 diameter and above.



Import three eccentricity metal sealing butterfly valve without directions, but generally recommend that you install direction, not anti-loaded; homemade directional, general reverse worse than being poor grades or a leak pressure of grades 1-2, can not be reversed. As in the horizontal pipe welding, the valve should be closed to protect the seals; such as in the vertical pipe welding, the valve should be closed, and in welding catchy board when the water valve to extinguish welding slag. In the horizontal pipe installed, it is recommended direction for the stem horizontal or vertical direction with a certain tilt to ensure the bearing at the bottom clean.



Rubber Soft Seal Butterfly Valve



Butterfly plate is generally plating ductile iron, rubber seals for. Sealing material used in a different performance is different. Commonly used are:



Dengqen rubber, for a temperature of 12 ℃ 1 +82 ℃; ethylene-propylene rubber, a temperature of 45 ℃ for 1 +135 ℃; heat-resistant ethylene-propylene rubber, a temperature of 20 ℃ for 1 +150 ℃.



There are commonly used in heating project on the clip-on (D371X), flange (D341X). DN125 can handle the following driver (D71, D41X). Pairs of clip-on butterfly lightweight, open and close fast, easy operation, and good installation, and easy maintenance, sealing and adjusting performance is superb, cost-effective, it should be vigorously used. Soft sealing butterfly valve no direction, can freely install.



Butterfly valve in storage, the valve plate to be opened 4 ° 1 5 °. So as to avoid prolonged pressure on the deformed ring affect the seal.



Check



Also known as check valve, single-stream door. Play a supporting role of a common valve.



How it works: to rely on its own strength as well as the fluid valve weight valve, automatic open and close the valve. As the name suggests, its role is to prevent the media back. Usually installed in the pump exit to prevent water hammer damage to the pump.



Heating projects are commonly used in the level of lift (H41H), Rosa xanthina Swing (H44H), double valve butterfly (H77H).



Directional valve, absolutely can not hold against. Different forms of check valve, according to their structure, have a fixed installation, must not be installed wrong. The level of lift can only be installed in a horizontal tube on the road, and ensure the valve flap in a vertical state; Rosa xanthina Swing can only be installed in a horizontal tube on the road, and ensure the valve flap shaft at the level of state; pairs of butterfly valve can be any installation.



Valve



Also called the throttle. Secondary heating system is a network of commonly used valves.



How it works: form, structure and similar cut-off valve. Sealing is only different from control valve valve seat valve and vacuum bottle like a cork and the bottle, through the valve flap movement changed to regulate the traffic flow area. In the valve axis, said there is a corresponding flow of the ruler.



Role: regulating pipe flow distribution between the media in order to achieve thermal equilibrium.



Heating projects have been using a straight-through (T41H), but it has some drawbacks: large flow resistance, not vertical installation. So as technology advances, balancing valve (PH45F) instead of the control valve.



Valves



Improved control valve. Flow channel using DC type, PTFE valve seat changed;



Overcome the shortcomings of a large flow resistance, while two additional advantages: seal more reasonable, both cut-off function.



Heating project in the second-line use of thermal stations, with excellent flow regulating characteristics, especially suitable for variable flow systems.



Directional and can be installed level can also be installed vertically.



Self-balancing valve



Also known as flow control valves. Its working principle is: there is a valve spring and the rubber membrane formed by the body, it is connected with the stem. If the flow rate increases, would generate an unbalanced force on it, making valve flap to close the move to reduce the flow area, reduce traffic, so that return flow settings. And vice versa. After the flow of this valve has always been to maintain the same, to control flow purposes.



Installed in the heating system, hot people, the branch point. Automatic elimination of hydraulic imbalance, improve system performance and achieve economic operation. Self-balancing valve directional, do not install anti-.



Valve



When the medium pressure exceeds the value, the valve automatically opens and pressure relief, when the pressure is normal, but also self-closing, in order to ensure normal operation of the system has played such a role is called the valve safety valve.



Divided by the structure: spring-type, lever type, pulse type.



The amount of points according to Action: Open the valve flap seat height and diameter ratio of 10% or less is called Enlight-type, 20% a 30% called the full-Kai style.



Excretion by way am: medium discharged through a pipe called a closed, directly discharged into the air called open type.



Now in order to make a brief spring, for example: the spring force acting on the valve flap and the media of normal pressure equilibrium, so that the sealing surface is closed; when the medium pressure is too high, the spring being compressed, valve plate to open the medium from escape; When the pressure back down to normal, the spring force turn the valve off.



A large number of valves used in pressure vessel.



Valve in the use of common problems



a) To maintain the cleanliness inside the valve.



b) lifting, the rope not tied on the hand wheel or valve stem.



c) before installation to confirm the valve is working correctly.



d) welding, the welding machine ground to ride in the welded joints of steel pipes on the same side, preventing damaging current valve.



e), small-caliber valve welding process cooling measures should be taken on the valve.



f) the pipeline does not always open and close the valve to rotate on a regular basis.



In addition, there is the use of environment on corrosion and protection of valve problems, media on the valve's internal corrosion and protection problems, temperature and pressure sealing and leakage problems and so on. In short, the valve is small, learning a great, yet we go to continuous learning summary. 

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Saturday, August 14, 2010

On the installation of regulating valves

With the scientific and technological progress, the production process automation used to control the fluid flow control valve has been widely used in various industries. For the thermal, chemical control systems, as the ultimate control of the process of media production targets of the quality and safety control valve, in the stable production, optimal control, maintenance and repair cost control plays an important role. In the regulation of valve applications, the calculation and selection is the prerequisite, installation and commissioning is the key, use and maintenance is the purpose. Regulating valve case of improper installation, or debugging is not good, not even come into the role of regulation, and even become a drag on the system.

     Valve Installation

     An installation of the basic principles of

     Regulating valve installation should follow the relevant national standards, in accordance with design drawings and design documents provided strictly enforced. For example, the construction and installation, inspection and evaluation of quality standards, industrial automation instrument construction and acceptance specifications, electrical equipment installation engineering construction and acceptance of standards, etc.; to install the required equipment, auxiliary equipment and key material should be consistent with the relevant provisions of existing national standards.

     2 pre-installation inspection

     Regulating valve and accessories from the factory to the installation before, during transportation by carriers excited by the random vibration and handling is subject to a variety of shocks, as well as in transport and storage process, the environment temperature, humidity and other changes, which can result in the performance of control valve and accessories change. Therefore, it is necessary to carry out part of the performance of pre-installation testing.

     Regulating valve pre-installation inspection includes the following elements: appearance, static characteristics, leakage volume, load the whole journey time, compressive strength, insulation performance, air tightness and sealing and so on, which will check for the previous five items. Of course, the test sites have certain requirements. For example: ambient temperature requires 10 ~ 35 ℃; air relative humidity of not more than 75%; the venue has sufficient space and adequate light or lighting conditions; around the local oscillator can not have sharp and strong magnetic field interference; power supply, gas supply meets the requirements.

     3 Installation Notes

     Regulating valve installation, the need to ensure safety, ensure the use of performance, ease of operation and maintenance, saving installation costs. Here's for the installation of these four points now need to pay attention to specific issues.

     3.1 to ensure the safety of

     1) To prevent leaks

     The installation process does not allow control valve leakage generated. The use of process, if the filling-han, flange gaskets and other parts of the formation of cracks or micro-leakage may arise. If the fluid medium harsh operating conditions, such as high temperature, high pressure, corrosive fluid, then the damage will be aggravated and the greater the risk of leakage. There are many ways to prevent the leakage in the installation process, the choice of filling and sealing method of choice, choose a good valve sealing performance, are all factors that must be considered.

     2) installation of relief valve

     Any one pipeline design and installation, cut off the plot when they inevitably have high-pressure fluid, if significant accumulation of fluid in the potential energy should be installed on both sides of valve relief valve, so that the system cut off, the control valve in the residual energy of high-pressure fluid can be released, to protect the safety of personnel is conducive to the maintenance of control valve may also be considering the selection to limit traffic relief valve.

     3) the safety of pipeline

     Before installing the valve, all fittings and pipeline installation should be clean, purge, because pipes in the sand, scale, iron filings, etc. may damage the inner surface of valve, particularly in demanding sealing surface. When the system pressure fluctuation in severe cases, it is recommended to install a buffer in the pipeline facilities. If the emission of harmful gas or liquid fluid is then used to discharge fluid piping must be connected to a safe location, you can also connect to the security of a specific container, so that can protect workers from harm, while it will not cause environmental pollution.

   3.2 ensure the use of performance

     Install control valve, you should try to ensure that its performance is not affected. This effect would undermine the control valve selection taken into account various factors.

     1) control valve on the upstream and downstream shut-off valve and bypass valve installation

     Upstream and downstream shut-off valve and control valve length of straight pipe between the pipe should be considered fluid flow resistance and the impact of the state. The length of straight pipe length is conducive to flow through the shut-off valve after the stability of steady fluid flow can reduce the impact of turbulent flow and reduce noise; straight pipe lengths short, the fluid through the shut-off valve after the valve has not yet entered a stable, so that the noise increase large, but the short length of straight pipe pipe helps reduce resistance, improve the control valve pressure drop at both ends, so that the distortion of reduced flow characteristics are conducive to the stability control system operation. Therefore, we should balance, comprehensive consideration. In accordance with experience, usually the upstream side due 10D ~ 20D of straight pipe upstream and downstream side of a 3D ~ 5D of the straight pipe section (D is pipe diameter), if necessary, should be set up rectifier unit.

     Valve demolition maintenance, the bypass valve can be used to operate the production process. When charged with the amount of traffic, with the regulating valve can not be properly adjusted, as a contingency measure, can also be used as a control valve bypass valve in parallel connection scheme, the process control. In order to reduce the cost of installing large-diameter hand wheel valve enforcement agency can replace the bypass valve to operate. Bypass valve installation should be easy to operate, with control valve and the upstream and downstream shut-off valve with integral regulator valve. Therefore, the control valve should be installed with shut-off valves and bypass valves matching considerations, and at the same time to complete construction and installation. Bypass valve nominal diameter and nominal diameter pipe the same pressure level pressure level is also consistent with the process.

     2) The discharge valve, venting valves, valve installation of sewage

     In order to facilitate control valve demolished, the demolition must be carried out before the valve before and after the pressure discharge valve, bleed valve should be installed in the control valve and the upstream and downstream between the shut-off valve. Venting valves and valves for the discharge of sewage flow in the entrainment of the non-condensable gases and condensate, if the installation was charged with the fluid is gas or steam, the condensate order to facilitate the discharge of sewage valve regulating valve installed in the appropriate minimum Department; when charged with fluid is a liquid, in order to facilitate the non-condensable gases, venting valve should install the highest office in the regulation valve.

     3) regulating valve and pipe connections

     Regulating valve and pipeline connection with threaded connections, flanged and welded connections distinction. Threaded connections for small-caliber valve installed, you must also install the activities of removable connector; flange connections of ordinary-type flange connection and two kinds of gripper-type connection, pipe connection flange nominal diameter should be adjusted valve diameter consistent pressure levels should also be level with the pressure regulating valve in line with the pipe flange vertical axis degree of allowable deviation of l °; try to avoid the use of welded connections. Regulating valve connection, should not link the emergence of new pipelines within the projections, for example, gaskets, welding seam should not have the inner bulge in the pipeline. At the same time, should pay attention to the flow of fluid within the valve body should be marked on the arrow in the same direction, in special circumstances may from time restriction.

     4) The installation of the implementing agencies

     In general, the implementing agencies directly connected with the regulating valve body, but the hydraulic implementing agencies, implementing agencies and other long-stroke and valve body separately, the installation of the implementing agencies should pay attention to the executing agency of the connecting rod and mechanical moving parts should be flexible, non - twist phenomena such as loose or card; rod length of appropriate, to ensure travel within the movement in the whole stable, flexible and reliable; hand wheel implementing bodies have two kinds of side-loading and top loading, the installation should be left room for maneuver, hand-wheel operation should be flexible , there is no stuck or reverse the phenomenon, there are hand-wheel rotation direction and the valve opening marked the relationship, limit devices should be adjusted to fit, has protective effects; hydraulic controller, implementing agencies should be lower than the installation, if the controller must be higher than the installation, the height difference should not exceed 1.0m, and shall remain in gas gathering pipelines to install exhaust valve, close to the controller, to install automatic shut-off valve.

     5) The installation of the valve positioner

     Valve positioner of the valve position detecting device and control valve stem or valve shaft directly connected, therefore, should ensure that feedback signals can be installed correctly in a timely manner to reflect valve position signal and change. Typically, the valve positioner and the control valve supporting supply, from factory to complete the connection between the two. When the production process control valve positioner needs to be added, should ensure the valve positioner valve position detecting device action is correct, reliable and flexible, mechanical feedback rod pivot gap should be as small as possible, valve positioner signal lines should be properly connected , gas pipelines and export pipelines source, enter the pipe should be marked; valve positioner valve position display signal should be conducive to the operation and maintenance personnel observations. 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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Metal seal butterfly valve in low-temperature device which practical application?

With the rapid development of industrial technology, for the valve industry, made more stringent requirements, especially for low-temperature media used in the butterfly, in addition to possess to meet the general performance of the valve and, more importantly, in low temperature under the valve seal reliability, flexibility of movement as well as a number of other low-temperature valve special requirements.



As we all know, Valve has a compact structure, small size, light weight (with the same pressure, the valve diameter compared to the same reduce the 40% ~ 50%), fluid resistance is small, open and close rapidly and a series of advantages. However, some of China's low-temperature devices such as days of burning liquid equipment, air separation equipment, and pressure swing adsorption equipment, valves used in chemical industry has more than 80% cut-off valve or gate valve, using a small number of butterfly valves. Analyze the main reason is too metal sealing butterfly valve at low temperature sealing performance under adverse conditions, as well as other irrational structure caused by internal leakage and dielectric leakage, serious implications of these low-temperature equipment, safety and normal operation can not meet the cryogenic equipment.



According to China's continuous development of low-temperature devices, the requirements for low-temperature valve and increasing the development of market economy to adapt to the needs of the metal sealing butterfly valve structural improvements, developed a three eccentric high-sealing properties of pure metal butterfly valve (Figure 1, has been declared national patent), whether the medium is high or low temperatures can meet their needs. Is combined with its structural characteristics, only the low-temperature performance, make a brief introduction.



1, for low-temperature disc valve sealing performance requirements



Produce low-temperature valve, there are two main reasons for the leakage of the situation, one internal leakage; second is leakage.



1) generated within the valve seal leakage mainly due to the Deputy at low temperatures caused a state of deformation. When the medium temperature dropped to produce the material phase change caused by volume change, so that the original seal with high precision surface grinding produces warpage caused by low-temperature seal bad. We have proposed to DN250 valves for low-temperature test medium is liquid nitrogen (-196 ℃) butterfly plate material 1Cr18Ni9Ti (not subject to low temperature treatment) found that the sealing surface warpage amounted to about 0.12mm, which is the main reason resulting in leakage .



The newly developed valve seals replaced by a flat cone seal. Is an oblique elliptical cone seat sealing surface, and embedded board is mounted on butterfly seal ring composed of circular elastic seal pair. Seal ring in radial floating butterfly board tank. When the valve is closed, flexible sealing ring first and the sealing surface of the short axis of contact ellipse, with the stem of the rotating seal ring gradually pushed inward, forcing elastic ring again and the long axis oblique cone surface contact, eventually leading to elastic sealing ring with an oval all contact with sealing surface. It relies on elastic sealing ring deformation and to achieve. So when the butterfly valve or plate deformation at low temperatures, when the seal ring will be flexible to absorb the compensation, will not produce the phenomenon of leakage and choked to death. When the valve opens, the elastic deformation disappear, in the process of basically not open and close relative friction, so long service life.



2) The leakage of the valve: one is the use of valves and pipe flange connections, because connections litter, connecting bolts, and connectors under the material at low temperatures are not synchronized between the contraction and relaxation lead to a leak generated. So we put body in connection with the pipeline replaced by a flange welded structure, avoiding the low-temperature leakage. The second is the stem and packing at the leakage. In general the majority of the valve filler with F4, because of its good performance from the sliding friction coefficient (for steel friction coefficient f = 0.05 ~ 0.1), but also has a unique chemical stability, so widely used. But the F4 is also inadequate, first cold flow tendency to large; second is linear expansion coefficient, at low temperatures lead to leakage resulting shrinkage, resulting in a large number of frozen stem Department to open the valve malfunction. To this end developed by low-temperature valve seal structure of a self-shrinkage expansion coefficient, namely the use of the characteristics of F4, through the gap to the left to reach room temperature, low temperature can be sealed purpose.



2, valve body, stem bushing design requirements



1) The low-temperature structure and shape of the shell valves. The correct choice of material or failure of the normal valve has an extremely reliable and important work. The structural characteristics of butterfly valves and globe valve, gate valve, compared not only to avoid a result of irregular shape, uneven shell thickness, at low temperatures resulting from shrinkage, thermal stress caused by the deformation, and because small butterfly , body shape is basically about is called, and thus heat capacity is small; to the consumption of cooling capacity is also small; shape of the rules would facilitate the valve cold measures. If the new model developed DD363H valve disc valves ensure reliable at low temperatures, the use of cryogenic valves in full accordance with the particularity of the design and manufacture, such as: shell material selection of a cubic lattice of 1Cr18Ni9Ti austenitic stainless steel.



2) The stem bushing choice: according to the user to reflect, and some low-temperature valve in the running among the rotating parts of the valve occurred viscous, occlusal phenomena have occurred, mainly due to: matching material selection reasonable, I stay in the cold gap is too small, and processing precision 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 selected with friction coefficient and self-lubricating properties of SF-1-type composite bearings, so that can be applied to some of the special needs of low-temperature valve.



Metal Sealed Butterfly Valve has the features of an ordinary valves do not possess. In particular, flow resistance is small, sealed, reliable, open and close rapidly, and long service life. The company developed three eccentric butterfly valve sealing ability of metal sealing ring from the elastic deformation to achieve sealing, thus eliminating the need with medium force, it can be done with a two-way seal. According to some characteristics of butterfly valves will be more people paying attention to. Butterfly in the future there will be more applied to the low-temperature devices. ball valve Trunnion Mounted Ball Valve Floating Ball Valve Top Entry Ball Valve ball valve V Type Ball Valve
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