Sunday, October 31, 2010

Body of a variety of materials commonly used materials and heat-treatment analysis

Body a wide range of materials for a variety of working conditions.



Body of nine commonly used materials are as follows:



1. Gray cast iron, apply to work in temperature between -15 ~ +200 ℃, PN ≤ 1.6MPa Nominal pressure of low pressure valve.



2. Black heart malleable cast iron, apply to work in temperature between -15 ~ +250 ℃, nominal pressure PN ≤ 2.5MPa in the low-pressure valve.



3. Ductile iron, apply to work in temperature between -30 ~ +350 ℃, nominal pressure PN ≤ 4.0MPa in the low-pressure valve.



4. Carbon steel (WCA, WCB, WCC), applicable to operating temperature -29 ~ +425 ℃ in between, the high-pressure valves, which 16Mn, 30Mn working temperature between -40 ~ +450 ℃, commonly used to replace ASTMA105.



5. Low-temperature carbon steel (LCB), applicable to the work temperature -46 ~ +345 ℃ valve between the low-temperature valve.



6. Alloy Steel (WC6, WC9), applicable to operating temperature -29 ~ +595 ℃ in a non-corrosive medium between the high temperature and high pressure valves; WC5, WC12 applicable to operating temperature in between -29 ~ +650 ℃ the corrosive medium high temperature and high pressure valves.



7. Austenitic stainless steel, for operating temperature -196 ~ +600 ℃ in the corrosive medium between the valves.



8. Monel alloy, the main medium for the valve hydrogen fluoride.



9. Copper alloy, mainly applicable to operating temperature -273 ~ +200 ℃ in oxygen pipe used between the valve.



Body mentioned above is commonly used materials in the major categories, specific for each type of material, many different grades and different grades also apply to a variety of pressure levels. So, the choice of valve body materials, should be based on different uses and different pressure levels to determine the conditions suitable for the needs of the body material.



In addition, the valve body materials are titanium (titanium valves), aluminum alloy (aluminum valves); plastics (plastic valve); ceramics (ceramic valves) and so on.



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. 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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Mill discharge lock overflow valve design and application of

Cement grinding system of air leakage is a common problem. System of air leakage not only increase the specifications of auxiliary equipment to increase the investment and operating costs, and will affect the system operating conditions, the system to increase production to reduce energy consumption. In addition to leakage caused by the reasons for the need for system processes (such as wind volume adjustment device, etc.) is inevitable, the equipment was mainly due to close (lock) closure device performance and caused by improper installation.



Participation in the mill grinding system, lock the end of the wind mill is good or not, with a direct impact on ventilation and grinding mill performance. Therefore, the choice of a good wind-lock device is the key to solve the problem of air leakage. Nanjing Cement Industry Design and Research Institute to develop the design of the mill discharge valve lock overflow with the principle of advanced features such as simple structure, it is more desirable to lock one of the wind plant, a cement plant in use more than the whole result is good, but some manufacturers of less than desired results. In this regard, our investigation and analysis, the main user of the device, the structure of a lack of understanding, together with the installation, improper use. Following on the device structure, principle, main parameters and applications and other matters they should pay attention for an introduction for readers to reference.



1 the main structure and its role



Lock valve by valve, repair the door, adjusting the composition of boards and inflatable box. Body from the middle of a fixed partition will be divided into Ⅰ, Ⅱ room, so that the formation of U-bed structure, to achieve the purpose of locking the wind. Maintenance is mainly used to the adjustment of the door panels to adjust and lock the detection of the effect of the wind. Adjustment plate is mainly used for material flow control and clean-up of iron. Inflatable box by the air layer, porous plates, etc., will the gas from the Roots blower evenly distributed at the bottom of the inflatable bed and the upper part of the material to form a fluidized bed state. In order to feed slag, iron and other coarse particles discharged in a timely manner, the level of inflation as me should be not less than 30 ° angle layout.



2 Working Principle



Lock overflow valve is designed Fluidization. The formation of a fixed fluidized bed process, in general be divided into fixed bed, fluidized bed and fluidized bed for three states. Figure 2 in the three states, the granular layer of the void fraction ε, when the fluid through the granular layer of the flow resistance and fluid u'f loss △ P changes. State in the fluidized bed, fluidized bed voidage with bed height increased with increasing ε, but the fluid bed through the actual velocity and fluidized bed u'f fluid resistance (neglected wall effect) has remained unchanged.



From the characteristics of fluidized bed, we can see that the stability of the flow of material flow conditions should meet the following formula:



F + (L1-L2) ρ g + (P1-P2)-V2 ξ ρ / 2 = 0? (1)



Where: F - per unit area on the momentum material, N/m2;



L1, L2 - Ⅰ, Ⅱ room high-effective material, m;



Ρ - material density after gasification, kg/m3;



P1, P2 - Ⅰ, Ⅱ expected upper chamber static pressure, N/m2;



V - the speed of material flow, m / s;



ξ - flow resistance coefficient, depending on the Ⅰ, Ⅱ Room of the channel between the cross-sectional area, factors such as inflation situation;



G - acceleration due to gravity, g = 9.8m/s2



Similarly, in the balance, the fluid through the fluidized bed pressure drop of △ P, can be obtained in accordance with the bed stress analysis:



△ P = L (1-ε) ρP g = L ρ g (2)



Where: △ P - fluidized bed pressure drop, Pa;



L - height of fluidized bed, m;



Ε - porosity of the fluidized bed.



By (2)-type, we can see that in the approximate pressure drop per unit area equal to the weight of the bed, that is, the static bed pressure drop has nothing to do with the air flow velocity. Lock overflow valve is to use the fluidized bed column resistance of materials to achieve the purpose of locking the wind. So, lock the wind conditions are as follows:



(L1-L2) ρ g ≥ P2-P1



3 Determination of the main operating parameters



Overflow valve lock the main operating parameters, including air pressure, wind and nesting capabilities, is as follows.



(1) air pressure. From the Roots blower and drums lock into the overflow valve to overcome the wind resistance of three, first, the expected effective fluidized bed resistance, and its value per unit area equivalent to the weight of the powder material; Second, Ⅰ, Ⅱ Room partitions resistance following material (including the effects of iron, etc.); Third, breathable layer and into the airway resistance. Practice has proved that the real effective lock wind resistance material used in total for the small proportion of wind pressure, so, regardless of whether the requested lock changes in wind pressure on the blower of choice for small wind pressure. FLS from Denmark provided information, we can see that requests me to the entrance of inflatable pressure 20kPa, and the relevant institutions for the experimental data? (10 ~ 25) kPa. Is therefore recommended that the actual choice of fan, the requirements for wind pressure (20 ~ 30) kPa can.



(2) air flow. From the formation of fluidized bed conditions, we can see that the appropriate cross-section increase in wind speed is essential. In the framework of a certain wind speed, wind speed and the size and the ability of nesting. Therefore, the air volume and air units of the size of the area. Table 1 shows the design parameters of some units. Combination of actual usage, I believe that the overflow valve of the air lock selected powder material per ton (0.35 ~ 0.40) m3 more appropriate range.



(3) discharge capacity. Capacity depends on the nesting material flow velocity and flow through the material, such as cross-sectional area. Expected to flow through the cross-sectional area is easy to determine, from the type (1), we can see that material flow velocity and flow resistance coefficient ξ, and the valve lock ξ with the geometric dimensions, material nature of the situation factors such as inflation, so , this calculation more complicated. Test in accordance with the relevant research institutions believe that the ability to discharge per unit area through the inflatable material to estimate the amount that may be nesting capacity (400 ~ 800) t h-1 m2 selected.



4 in use should be noted that several issues



In addition to understanding the use of overflow when the lock valve structure and principle, we must also pay attention to the following questions:



(1) should be checked prior to installation damage permeability layer, or by rain water and so on. If it exists, should be eliminated, so as to avoid wind or blockage of string. Roots blower away from the overflow valve lock, the connection pipe must be added support to prevent vibration generated.



(2) the beginning of use, to observe the material flow through the adjustment plate to adjust material flow through the cross-section size, to achieve the speed of material flow control.



(3) When the value of L1 and L2 is too small, the bed may be expected to penetrate the air or wind run, wind not the purpose of locking. Therefore, at the beginning or in the mill system is not functioning normally, it is possible that this phenomenon of attention.



(4) through the overflow valve at the top of lock repair lock the door to detect the wind effects, if negative pressure here at the micro-state, indicates that the wind a good lock; the other hand, should be adjusted.



(5) of the overflow valve lock plate to adjust the export side of adjustment, can not access all the lower part sealed to avoid long-term operation, the iron will be expected to plug the flow of Road. But they can not be too large in order to prevent short-circuit feed stream, the impact of air lock. 

  

  

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Saturday, October 30, 2010

Smoke damper valve applications in engineering quality requirements (b)

2.2, the regulating role



In ventilation, air-conditioning system piping design, though calculated, but in the actual operation of the project if there is a change in working condition, you need to through the damper parts of the valve system to regulate the air flow for system debugging, the valve fixed aperture, a reasonable allocation to meet the design requirements.



2.3, start the empty role of



Ventilation and air conditioning and smoke extraction systems and fire all centrifugal fans a dedicated exhaust axial flow fan, in the installation and commissioning, in order to ensure safety, so that the minimum starting current motors, are generally no-load start, temporary cut-off line through the valve to achieve .



3, the quality requirements of engineering applications



3.1, product quality requirements



At present, fire prevention, smoke a lot of product manufacturers, we are monitoring the fire, to build trial and the design department should be strictly controlled, so that Party A selection of the "three card" complete, qualified products, the manufacturers have factory certification, organs of public security fire sales permit, the National Fire Protection Building Materials Center for Quality Supervision, Inspection and product inspection reports. Inspection reports from the national-level technical parameters and products that can be reflected in the performance and quality products, on the basis that the national standard "test method damper" GB15930-1995 and "test method smoke damper" GB15931-1995. Quality requirements for their products reflected in five areas:



3.1.1, Temperature Sensor Performance Test action



Of fire dampers, flue gas temperature and valve components, respectively, by the constant temperature water bath, oil bath temperature, through non-action and motion tests, examinations of whether the temperature required to accurately closed.



3.1.2, the closure of the reliability of test



Shut down operation in the test stand 250, the sample from the open position should be flexible and reliable shut down, the parts should be no significant wear, deformation and impact damage to its sealing performance. In order to test the reliability of the closure.



3.1.3, salt spray test



The specimen to spray me in the salt spray test, the sample should be able to reliably shut down the open position in order to test the valve in the actual works in the corrosion resistance.



3.1.4, the air leakage test



Valve pressure differential before and after the required conditions, the sample volume per unit area of air leakage not more than 700Nm3 / (h m2), in order to test the valve closed after the closure of the performance.



3.1.5, the fire resistance test



Through the fire resistance test, in accordance with the provisions of the closure time and the amount of air leakage per unit area of the two indicators to determine the fire resistance of the valve.



In addition the technical parameters from the products of its fire resistance requirements for 3h. 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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How to solve the valves in the course of the common minor problems

1, why is a small two-seater valve opening hours of work likely oscillation?

     Pairs of single-core, when the medium is open-type flow, the valve stability; when the medium is a closed-type flow, the valve of the stability of the difference. There are two spool valve seat, the next spool in the flow of closed, open on the spool in the flow, so that a small opening in the work, the flow of closed-type valve spool is easy to cause vibration, which is two-seat valve can not be used for the work of a small opening reason.

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

     Two-seat valve spool force balance the advantages of the structure, allowing large differential pressure, and its obvious drawback is that two sealing surface can not be good contacts at the same time, resulting in large leakage. If it is artificially Mandatory used to cut off occasion, apparently ineffective, even if it made a lot of improvements (such as the double-sealed sleeve valve), is also undesirable.

3, what straight poor performance, aiming to halt the stroke control valve, angle valve, prevent the travel of good performance?

     Direct travel is vertical throttle valve spool, while the medium is the level of flow into the outflow valve cavity flow channel bound to turn down Shui Po, so that the valve flow path becomes quite complex (shape such as the inverted "S" type). In this way, there are many dead zone, the precipitation of the medium provides a space for the long run, causing blockage. The direction of travel throttle valve angle is the horizontal direction, the level of flows into the medium, the level of outflow, easy to clean media is not removed, flow path at the same time simple and very little room for medium precipitation, therefore, prevent the valve angle stroke of good performance.

4, why do straight stroke adjustment valve stem smaller?

     It involves a simple mechanical principle: sliding friction, rolling friction small. Trip valve stem straight up and down movement, packing slightly pressed a little, it will stem bag tightly, resulting in a larger backlash. To this end, valve stem is designed to be very small, they often fill a small
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How to solve the dynamic sealing valve and static sealing problem?

How to solve the sealing problem can not be ignored, because the valve run, risk, dripping, and drain phenomenon, the vast majority took place here.



Dynamic Sealing



Dynamic seal valve, mainly refers to the stem seal. With the valve stem to prevent movement within the media leak, is the central subject of dynamic seal valve.



Stuffing Box Type



At present, the dynamic seal valve to the main stuffing. Stuffing the basic form is:



(1) gland-type



This is the most used form.



The same form can distinguish many details. For example, from the clamping bolt, the bolt can be divided into T-shaped (for the pressure of ≤ 16 kg / square centimeter of the low-pressure valve), double-headed bolts and bolts of living sections. Speaking from the gland can be divided into integral and modular.



(2) compacting Nut



This form, shape, small size, but the clamping force is restricted to use only in small valves.



Filler



Stuffing in order to fill in direct contact with the valve stem, and filled with stuffing to prevent media leakage. On the filler has the following requirements:



(1), sealing well;



(2) corrosion resistance;



(3) The friction coefficient is small;



(4) to adapt to medium temperature and pressure.



Common fillers include:



(1) packing Asbestos: asbestos packing, heat and corrosion resistance are good, but when used alone, sealing results are poor, it is always impregnated or additional other materials. Oil asbestos packing: its basic structure, there are two, one is a twisted system, the other one is knitting. Also can be divided into round and square.



(2) PTFE braided packing: The packing of PTFE thin braided belt, has an excellent corrosion resistance, but also for deep-cold medium.



(3) Rubber O-ring: In the low state, a good sealing effect. Temperature subject to limitations, such as natural rubber can be used only 60 ℃.



(4) plastic molding packing: General made three-piece, but also can be made into other shapes. PTFE is used in plastics in many, there are nylon 66 and nylon 1010.



In addition, the use of units according to their own needs, often to explore an effective form of packing. For example, in 250 ℃ steam valve, the use of asbestos and lead-lap alternately Diego packing together, the situation would reduce the steam leakage; some valves, media constantly changing, such as asbestos packing and PTFE THREAD SEAL TAPE common use, sealing effect will be better. To reduce the friction between stem, and some occasions, can be added molybdenum disulfide (M0S2), or other lubricants.



Currently, new fillers, are engaged in exploration. Such as using polyacrylonitrile fiber impregnated by PTFE emulsion, but also by the pre-oxidation, in the mold sintering suppression, can be sealed-performance molding filler; Another example is made of stainless steel sheets with asbestos filler waveform can be high temperature , high pressure and corrosion. 

 

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Friday, October 29, 2010

Process control valve should be how to choose (a)

Regulating valve in the role of process control is to accept or adjust the computer's control signal, changing the flow of medium was transferred to be transferred within the required parameters to maintain the framework of the production process so as to achieve the automation. If the automatic adjustment system and the manual adjustment process, compared to detection unit is the eyes, and adjust the control unit is the brain, then the unit is the person's hands and feet, regulating valve is the people's hands and feet. Process to achieve a certain parameters such as temperature, pressure, flow, level of regulation, such as control, are inseparable from the control valve. Therefore the correct choice of control valve automation in the process of great significance.



The composition of a control valve and classification



Also known as the control valve control valve is the main type of actuator, control unit through the acceptance of adjustment of the control signal output, with power to change the fluid flow operation. Regulating valve is usually composed of the implementing agencies and valves. If the use of its executive body with the power to regulate the valve can be divided into pneumatic, electric, hydraulic three, that is the source of compressed air as a driving force of the pneumatic valve to electrical power source for electric control valve to liquid medium (such as oil) pressure-driven dynamic electro-hydraulic control valve, while, according to their functions and characteristics of sub-, and solenoid valve, electronic, smart, on-site, such as bus-type regulating valve. Control valve are many types of products, a variety of structure, but also constantly updated and changes. Generally speaking valve is common, both implementing agencies and pneumatic matching can also be the executing agency and the electrical or other executive body to match.



2 Select the type of control valve



2.1 Control Valve Valve Valve type control valve of choice is to choose the most important aspects. Many different types of control valve body, are commonly used straight-through single-seater, two-seater straight, angular, diaphragm, small traffic, links, eccentric rotation, butterfly, sleeve, spherical, such as 10. Prior to the selection of valves, to control the course of the medium, the process conditions and parameters of careful analysis, to collect sufficient data to understand the system requirements on the control valve, according to the data collected to be used to determine the type of valve. Specific options, available from the following considerations:



(1) spool shape chosen primarily on the basis of the structure of the flow characteristics and to consider factors such as unbalanced force.



(2) abrasion-resistant when the fluid medium containing high concentrations of wear particles of suspension, the valve core, valve seat joints will be shut down every time a serious friction. Thus the valve flow path to smooth, the internal valve to a hard material.



(3) as a result of corrosion-resistant medium is corrosive, can satisfy the regulatory function in the circumstances, the valve structure is simple as we choose.



(4) medium temperature and pressure when the medium temperature, pressure and changes in the high when the valve core and valve seat should be used by the material temperature, pressure changes in the small valve.



(5) to prevent the flash and the flash cavitation and cavitation generated in the liquid medium only. In the actual production process, the flash and the air flow of not only affect the calculation of coefficients, but also the formation of vibration and noise, so that shorter service life of valves, the valve should be in the selection of flash and have a valve to prevent cavitation . 

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Surge irrigation controller control valve and self-development

Surge irrigation systems in general by the surge irrigation control valves, automatic controllers, water pipelines and other equipment, including control valves and the entire system since the controller is the core equipment. The current surge in foreign countries have irrigation control valve market. In recent years China has imported several sets of surge irrigation equipment, as a result of the high cost, only for a limited number of pilot studies. Taking into account the water-saving irrigation and irrigation automation is an inevitable trend of future development, the development of conditions suitable for surge irrigation equipment is very necessary. Conjunction with national "Ninth Five-Year Plan" scientific and technological project, after several years of efforts, has developed a surge irrigation control valves and automatic controllers, the preliminary results achieved.

         1 surge irrigation equipment components

         1.1 Surge irrigation control valve

         Automated irrigation, taking into account the needs of irrigated areas, the development of surge irrigation control valve structure using two-way switch to switch the direction of water flow to promote, in accordance with instructions from the controller to achieve the intermittent water supply to control the process. Especially in unattended mode, after the end of irrigation can be automatically cut off the water quickly to avoid waste caused by excessive irrigation. Control valve materials currently made from iron, the main component elements include: valve, valves and slow down box.

         Body structure similar to three, from three diameter 200 mm (8 ") combination of iron pipe linking one end and water connected to the outlet at both ends. Valve gasket for sealing a periphery of the circular gate, in which upper and lower ends of the central axis by the bearing seal with the body and slow down box to connect. by Gearbox control gates at right angles around the central axis for rotation, to achieve the current state of open and closed. Gearbox closed valve was fixed in on both sides and through the central axis of phase with the gate. box with: (1) transmission, taking into account the work of worm drive with a smooth noise-free, etc. can be self-locking, the design of the ordinary cylindrical worm and worm gear reducer drive; (2 ) drive, the gate valve used to control micro DC motor; (3) Locator by light control and light control panels, designed to determine the status of the valve gate; (4) reducer, high-speed operation motor (3 000 r / min) speed reducer through the levels to 10 r / min or so, and then drives the valve; (5) buffer to prevent motor overload and ensure the valve closed state.

         1.2 Automatic Control

         Since the surge controller is the control center of the irrigation system, control circuit board and software is the core of the controller, it accepts manual input of parameters, surge valve operating instructions issued to achieve the turn of the gate headstock. Location by the photocell gate position controller phototube signal received before deciding whether to hoist motor. Since the main controller of the following parts.

         Control part. 89C518-bit microcontroller used as the core, with the composition of the keyboard and display. Keyboard used to set the system time, starting time for each irrigation time, intermittent time and frequency surge. These input parameters are automatically saved, power down or power-down is not lost. 6 LED display by the digital control of the display parameters and the working hours of state, due to the lower-power scanning. System clock for the 24 h system, the use of back-up batteries, shut down after the clock is still working correctly.

         Part of motor control. 74LS07 driven by 4 relays, push the motor left and right rotation gate. When not working at both ends of the electrical grounding. When the motor is to the left termination +6 V, the right end of the ground, inverted, then left grounded, then the right end of the +6 V.

         Part of the location of sensor. From 4 optocoupler, namely the two gates of the switching instructions, and will return control to receive part of the signal.

         Power part. By the solar panels, 4 Ah / 6 V battery and power supply reverse anti-LDO regulator LM2940 device components. Solar panels normally float on the battery. Surge irrigation system, the batteries provide power for equipment and supplies through the main board after the LM2940 voltage regulator. Taking into account the exceptional circumstances, power is also equipped with the exchange of charging system.

         Function to select some. With "control" button to select the operating mode surge valve, the controller can control the left valve, right valve or double valve, to achieve full clearance, wide-open, single-valve operation of features such as alternate.

         Operation, including the application of controller parameters and control settings to run in two parts. Controlled operation is received after some of the basic input parameters, the operator control procedures, issued a directive by the control center automatically. The operation parameters are as follows: (1) Open the power supply, surge control valve will automatically reset - about the closure of the valve at the same time; (2) select the "control" to determine the work of surge valves, and options are left valve, right valve, double valve; (3) Select "System time" with "hours / minutes / seconds" button to choose the time target, and adjust the system time "+","-"; (4) Select "Start Time "with" hours / minutes / seconds "button to choose the time, using surge irrigation "+","-" adjusted starting time of the incident; (5) Select" water time "with" hours / minutes / seconds " button to choose the time object, identified by a single "+","-" surge irrigation water advance time; (6) select "time interval", the "hours / minutes / seconds" button to choose the time object, use "+", "-" to identify a single time surge irrigation water; (7) select the "surge the number of" surge adjusted by the number of "+","-", every time "+" in the second digital tube plus 1 , the largest to 99, every time "-" in the second tube by a digital 1, the minimum to 0.

         After the above settings, the controller to enter the working state automatically. To show that the dual-valve control means "left-open right off" or "right-open left off" the work of the state of the turn, when the "time interval" greater than or equal to "water time", in a cycle at the end, the two valves will be At the same time, the closure of the closing time for the "time interval" minus the "water time", the second round after the work of the state of the cycle; when the "time interval" less than "water time", two-valve can not work at the same time, the circumstances, the only to single valve operation. Any time, once by pressing the "system reset" button, surge valve around the valve will be shut down, thus the termination of the irrigation.

         1.3 Control valve and self-controller connections

         For ease of use, to avoid illegal or misoperation, surge valve controller and interface standards for the use of industrialization, the connection between the two can use to plug your cable (only can be inserted), simple, safe operation.

         2 device performance and characteristics of

         Developed surge irrigation equipment has the following properties and characteristics of the work.

Two-valve condition, the single biggest surge over flow valve and the corresponding Q of the irrigated area can be controlled using the following formula to estimate S



         Which

         Where A cross-sectional area for water pipelines; d is the diameter of pipeline; ε for the discharge coefficient; h for Agricultural Drainage Department at the outlet of pressure head; λ for the coefficient of head loss along the way; ξ for the local head loss coefficient; L for length of pipeline; T for rotation irrigation cycle; m fixed for irrigation; t time daily irrigation; η is coefficient of effective use of water. Schedule is given the assumption that crop rotation irrigation cycle for 7 d, the daily irrigation time of 12 h, different pressure pipeline length and head combinations calculated by the single had the biggest surge valve flow Q and the corresponding control of the irrigated areaæ•°è´¨. Irrigation Area on the run, when agricultural drainage outlet at the head of water pressure for Office 30 ~ 50 cm when surge irrigation equipment control area is 4 ~ 6 hm2, in well irrigation area, the control will depend on the size of the surplus pump motor-pumped wells head.

         Schedule single had the biggest surge valve to control flow and the corresponding estimates of irrigated area

         Head H / m pipeline length L / m

         L = 25 m L = 50 m

ε Q/m3.s-1 S/hm2 ε Q/m3.s-1 S/hm2

0.3 0.4 0.030 5 4.61 0.324 4 0.024 7 3.74

0.5 0.4 0.039 4 5.95 0.324 4 0.031 9 4.83

0.8 0.4 0.049 8 7.53 0.324 4 0.040 4 6.11

1.0 0.4 0.055 7 8.41 0.324 4 0.045 1 6.83

1.5 0.4 0.068 2 10.31 0.324 4 0.055 3 8.36

2.0 0.4 0.078 7 11.90 0.324 4 0.063 8 9.65

Note: d = 0.2 m; λ = 0.026; Σξ = 2; m = 750 m3/hm2; η = 0.75.

         Since the controller operating voltage 6 V, the average operating current 2.5 A, switching time T = 3 s, battery energy storage to 4 Ah / 6 V. Theoretically, the work of number of 1 920 times, the corresponding surge in terms of the number of double-valve for 480 times on a single valve is 960 times. By the processing equipment, installation limited accuracy, the actual power consumption will be lower the larger the battery the work of a number of charge. Nevertheless, the volume of a charging or operation to meet the irrigation demand for energy gate valve.

         The size of solar panels for the 152 mm × 152 mm, the corresponding theoretical power of 1 VA, in the normal light of the average voltage of 8 V, the average charge current is 0.1 A. After the battery fully discharge full time for about 30 h, if the effective charge per day calculated 6 h (10:00 to 16:00), then 5 d. It is suggested that each Director prior to use should be placed outdoors since sunlight charging to ensure the safe operation of a week.

Taking into account the structural design of a multi-valve, and can be used as a single-tube system, but also pay for the replacement of two-pipe system to use the equipment to increase flexibility. Equipment with automatic turn-off water features, can be remote controlled and unmanned.

         Controller parameters is simple and involves only the most basic surge irrigation parameters, which will help farmers learn to grasp and easy to promote the use of the field.

         Equipment is simple, users will only power cable and surge valve controller can be put into use to connect, and the controller and the speed of the interface box to protect the use of water-proof dust-proof, and suitable farmland in the field of climate and environment conditions.

         3, the initial field test

         Developed surge irrigation equipment in 1998 was well irrigation and drainage Irrigation District irrigation of winter wheat trials conducted a preliminary field evaluation. Surge intake valve and low pressure hoses used PE aqueduct or agricultural drainage outlet connected at the outlet, and the two surge outlet valve from the hole with the many farm gates hose system. Hole on the brake hose directly into the furrow irrigation water. Experimental design is a single-wide flow of 0.003 m3/sm, furrow length of 150 ~ 200 m, test results show that the work of the whole equipment running well and Surge gate valve to the normal free variable, the accuracy of the flow switching time, the effect of the gate seal better achieve the original design requirements and performance indicators, with a strong practical field.

         Assessment results also indicate that the equipment can be very convenient in well irrigation area in the application, on the one hand, the existing low-pressure pipelines can be a convenient outlet and inlet valve surge phase, the surplus on the other hand well pump pressure head for water hose by the PE to provide sufficient power to ensure that a surge into the furrow irrigation methods on the request of discharge. Irrigation Drainage surge valve used will be the two factors. One from the Department of agricultural drainage water head pressure at the outlet of the restriction, when the head must, the water hose and the head loss along the way Surge irrigation equipment produced by their own local head loss will lead to reduced flow into the plot, can not satisfy the wave Chung irrigation requirements of technical parameters. Based on the test results, channel outlet pressure head Department should at least be greater than 30 cm, surge valve pipeline length and it is not too long. The second is the need for the existing agricultural drainage outlet to the appropriate transformation of the structure so that its intake valve surge convergence.

         4 Conclusion

         Conditions suitable for the development of surge irrigation equipment is to achieve large-scale application of this water-saving irrigation methods, one of the necessary conditions. Has developed a surge of irrigation control valves and automatic valve controller has a multi-purpose, easy to operate features. Preliminary assessment field trial results show that the equipment has reached the design requirements and performance indicators, with a strong practical field. On this basis, will further enhance and improve the control valve and controller since the quality and standards, the use of lightweight materials to replace existing materials, to reduce equipment weight and easy to field mobile and flexible. In addition, the development of surge irrigation equipment and matching the field and the corresponding aqueduct pipe fittings such as gate-hole, thereby providing a good performance, modest prices surge irrigation system complete. Reason to believe that, with the surge irrigation equipment to improve the success of the development and improvement of irrigation system, as well as surge production series surge irrigation technology will be able to water-saving irrigation cause in our country to play its due role. 



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New materials and new technologies


The above described sealing washer is far from comprehensive, Moreover, sealing technology is in rapid development. The following examples of a number of new materials and new technologies.



(1) Liquid Seal: As the polymer industry, the rapid development of organic synthesis in recent years emerged liquid sealant, used in static seals; this new technology, often called the liquid seal. Fluid sealing principle is the use of liquid sealant adhesion, mobility and single-molecule membrane effects (the thinner the membrane the greater the tendency of the natural reply) and, where appropriate under pressure, making it the same way as the washer works. Therefore, the use of a sealing adhesive, also known as liquid gasket.



(2) PTFE sealing raw materials: PTFE is also a high molecular organic compounds, it is sintered into a product before, called the raw material, texture soft, there are single-molecule membrane effect. Using raw materials made of raw materials with a known band, long-term preservation can be rolled into a plate. Are free to use shape, any joints, as long as a pressure, this will form an evenly played the role of ring sealing membrane. As the valve body and valve cover gasket, you can not remove the valve flap or damper circumstances, forced open a gap, into the raw material brought on the list. Clamping force is small, non-stick in hand, but also non-stick flange, the replacement is very convenient. Mortise the most suitable for the flange. PTFE raw materials can also be made of tube and rod for sealing use.



(3) Metal hollow O-ring: good elasticity, clamping force is small, there is self-energizing effect, the choice of a variety of metal materials, resulting in low temperature, high temperature and strong corrosive media can adapt to.



(4) graphite plate seals: in people's minds, graphite is a brittle material, the lack of flexibility and toughness, but after special treatment of the graphite, but it is soft, flexible sound. In this way, graphite heat resistance and chemical stability, they can be displayed in the gasket material; and this washer clamping force is small, a very favorable sealing effect. This also made of graphite tape, with the metal strip with the form-performance wound gasket. Graphite plate seals and graphite spiral wound gaskets ---- The emergence of high temperature corrosion-resistant sealed a major breakthrough. Such washers have a large number of overseas production and use.



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Thursday, October 28, 2010

Depth analysis: China's solenoid valve technology, the new development (a)

Solenoid valve as an automatic instrument actuator, the amount of a sharp increase in recent years. This paper analyzes the main characteristics of the solenoid valve and the angle of focus on the domestic application of mature technologies for a brief overview of developments, namely in the streamlining, intelligence, common and dedicated direction of study, and a little of the impact of solenoid valve technology development point to explore the social factors.



First, the main characteristics of the solenoid valve



(1) no leakage plugging, easy to control with the leakage, the use of security. Internal and external leakage is a factor likely to affect safety. Other controlled valve stem out usually by electrical, pneumatic, hydraulic spool control the implementation of the rotation or move. This action should address the long-term dynamic stem seal leakage problems of the outside; only electromagnetic solenoid valve is sealed in the following works for the magnetic core within the casing to complete, there is no dynamic seals, the leakage can easily block. Electric torque control valve is not easy, prone to leakage, and even pull off the head stem; the structure type solenoid valve with easy to control the leakage until zero. Therefore, the use of special safety solenoid valve, in particular, applicable to corrosive, toxic or high temperature media.



(2) the system is simple, will take computers, low cost him. Solenoid valve itself simple structure, low prices, compared to other types of control valve actuators, such as easy installation and maintenance. More significant is the composition of the automatic control system is much simpler, much lower price. Solenoid valve is switched due to signal control, and industrial control computer is very convenient to connect. Universal in today's computers, an era of declining prices, the solenoid valve on the more obvious advantages.



(3) Action Express, power tiny, lightweight form factor. Solenoid valve response time can be as short as a few milliseconds, even if the pilot-type solenoid valve can be controlled within a few dozen milliseconds. As the self-loop, other than more responsive control valve. Properly designed coil of solenoid valve power consumption is very low, an energy-saving products; action could also be just the trigger to automatically maintain valve position, usually is not power. Small size solenoid valve, saving space and beautiful light.



(4) regulation accuracy is limited, restricted the application of media. Solenoid valve switches are usually only two states, two spool limit has been placed in a position, not for regulation, (trying to break through a lot of new ideas, but also are in the pilot phase of the trial), so regulation accuracy is also subject to certain restrictions.



Solenoid valve on the media have a higher cleanliness requirements, including granular media can not be applied, in the case of least squares must impurities. In addition, the viscous-like medium can not be applied, and applies to specific products relatively narrow range of medium viscosity.



(5) models of diversity, a wide range of uses. Notwithstanding the inherent electromagnetic valve, the advantages are still very prominent, so a wide range of products designed to meet the different needs of a wide range of uses. Solenoid valve technology is also centered on how to overcome the deficiencies, how to give better play to the inherent advantage to start.



Second, technological development solenoid valve solenoid valve technology More About



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Traps the correct selection of conditions for

1. Trap the sparse amount of water:

     Use traps, you must press equipment, the consumption of steam per hour multiplied by the selected magnification 2-3 times the maximum condensation of water, to select the trap displacement. Can we ensure that trap while driving discharge condensate as soon as possible, rapid increase in the temperature of heating equipment. Trap emission energy is not enough will cause condensation of water can not be discharged in time to reduce the thermal efficiency of heating equipment. (When the steam started to send steam heating equipment, the device is cold, inside filled with air, need to trap the air quickly discharged, and then row a large number of low-temperature condensation of water, gradually heat up the equipment, and equipment in normal working condition. As the car When a large number of air and low-temperature condensation of water, a lower inlet pressure, so that overload trap to run, this time Trap than normal working hours require a displacement of large, so use magnification by 2-3 times to select the trap.)

2. Trap working pressure:

     Selected trap, the trap can not be selected nominal pressure, as nominal pressure can only say that traps body shell pressure rating, trap nominal pressure and work pressure varies greatly. Therefore, according to the work of pressure to select the trap displacement. Working pressure is the pressure minus the pre-trap trap the difference between exports of backpressure. After the back-pressure steam trap is calculated by: (when condensed water is discharged into the atmosphere after the steam trap, the trap back pressure is zero exports. If the concentration of traps discharge condensate recovery, this time, the export of back-pressure steam trap is a return to the resistance of pipes, water pipes back to a high elevation, the second evaporator (back to tank) and the internal pressure of the three.)

3. Mechanical-type steam traps Seat number:

     Mechanical-type trap according to different working pressure section of the valve seat aperture is divided into a variety of specifications of "seat number", each segment of work pressure and the "seat number" composed of a coordinate displacement curve, different "seat number "of the sparse amount of water are very different. Mechanical-type traps should be based on process conditions of the maximum working pressure and the maximum displacement of the two curves corresponding to the coordinates of the election the right "seat number." Can not be determined nominal pressure to "seat number", if the wrong "seat number", there may be water in traps do not work or equipment, affecting the normal operation of equipment.

4. Trap operating temperature:

     Use traps when the maximum temperature according to the steam pipes to choose the process conditions to meet the requirements of traps. The maximum temperature of more than nominal pressure steam pipe that corresponds to the saturated steam temperature referred to as superheated steam, superheated steam pipe selection in the trap, they should use special high-temperature high-pressure superheated steam trap.

5. Trap connection size:

     The decision process conditions trap after the trap before and after the work under the pressure to drain water and the "seat number", according to the technical parameters of trap manufacturers to choose the size of trap specifications. (Can not connect the device size of random matching according to the same size of the trap, trap connection caliber can not represent the sparse amount of water the size of the same caliber of the trap, the hydrophobic capacity may vary widely; So when you use traps must be based on the device process conditions, in the light trap manufacturers matching parameters provided by the trap is the correct choice.) ball valve Trunnion Mounted Ball Valve Floating Ball Valve Top Entry Ball Valve ball valve V Type Ball Valve
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Widespread use of pneumatic control valve and routine maintenance of

   Pneumatic control valve is widely used in petroleum chemical industry is one of the instrument. It is precisely to work properly in ensuring the normal operation of process plants and production safety have an important significance. Therefore, strengthening the pneumatic valve repair is necessary.

First, repair parts, when the focus of inspection



Check between the body wall: In high-pressure differential and corrosive media of the occasion, body wall, diaphragm of the diaphragm often media impact and corrosion, we must focus on examination of pressure decay;



Check Seat: Due to the work of media penetration, fixed seat screw used in the inner surface susceptible to corrosion Ershi seat relaxation;



Check spool: spool valve to regulate one of movable parts, subject to more severe erosion of the medium, repair should be careful when you check the valve core ministries is corrosion, wear and tear, especially in the case of high-pressure differential, spool of wear due to cavitation caused by cavitation phenomenon is even more serious. Were seriously damaged valve core should be replaced; check Filler: Check the packing asbestos rope is dry, such as the use of PTFE packing, should pay attention to check whether the aging and its mating surface is damaged;



Check the executive body of the rubber membrane is aging, whether the cracking phenomenon.



2, pneumatic control valve with daily maintenance



When the control valve using graphite asbestos as a filler, the filler should be about three months to add a lubricant to ensure the control valve and flexible easy to use. Found filling pressure cap low, should be added fillers, such as found in the dry filler PTFE B sclerosis, should be promptly replaced; should pay attention to inspection tour of the operation of control valve, check valve position indicator and regulator the output is consistent; to have locator control valve should always check the gas source, identify problems and timely treatment; should always maintain a control valve components of health as well as a complete easy to use.



3, common faults and their causes



(A) the control valve does not move. Phenomenon and the reasons for failure are as follows:



1. No signal, no gas source. ① gas source is not open, ② gas supply due to water freezing in the winter, leading to blocked ducts or filters, valve block failure, ③ compressor failure; ④ source of mains gas leak.



2. There is gas source, no signal. ① regulator failure, ② the signal tube leakage; ③ bellows leak locator; ④ regulate film damaged retina.



3. No gas source locator. ① filter plugging; ② valve failure I ③ pipeline leak or blockage.



4. Positioning device has gas supply, no output. Locator orifice plug.



5. There is signal, no action. Spool off ①, ② spool with the social or stuck with the valve seat; ③ stem bending or breakage; ④ spool seat block of frozen or coke dirt; ⑤ implementing agencies do not have the spring due to the long-term rust die.



(B) the control valve moves instability. Phenomenon and the reasons for failure are as follows:



1. Pressure gas source of instability. ① compressor capacity is too small; ② valve failure.



2. The signal pressure instability. ① control system time constant (T = RC) inappropriate; ② regulator output instability.



3. A stable gas supply pressure, the signal pressure is stable, but still stable valve action. ① Locator amplifier ball wear off by the dirt loose, especially with increasing gas consumption will produce the output shock; ② Locator amplifier nozzle baffle is not parallel to baffle nozzle cover not live; ③ Output Pipe, line leak; ④ executive body rigidity is too small; ⑤ stem movement friction large parts of a block in contact with the phenomenon.



(C) regulating valve vibration. Phenomenon and the reasons for failure are as follows:



1. Regulating valve opening at any vibration at all times. ① supporting instability; ② near the source of vibration; ③ spool and bushing wear serious.



2. Regulating valve near the fully closed position vibration. ① big selection valve, often used in small openings; ② single-seat valve media flow on and off in the opposite direction.



(D) regulating valve movements slow. Slow phenomenon, and the following reasons:



1. Stem only in one direction when the slow movement. ① pneumatic membrane leakage of the implementing agencies in the membrane damage; ② implementing agencies in the "O" type seal leakage.



2. When the stem at reciprocating movements are slow phenomenon. ① valve body with sticky material to plug; ② sclerosis or graphite PTFE packing deterioration of asbestos packing a dry lubricant; ③ packing too tightly increases, friction increases; ④ stem not directly lead to friction due to large; ⑤ No The pneumatic control valve positioner can lead to slow movement.



(E) increase the amount of valve leakage. Leakage of the following reasons:



1. Valve fully closed when the leakage of large quantities. ① spool is worn to a serious internal leakage, ② strictly off valve is not a good tune.



2. Valve fail to fully closed position. ① medium pressure too great, the executing agency rigidity is small, loose valve closed; ② of a foreign body within the valve; ③ sintered bushing.



(F) adjustable flow range becomes smaller. The main reason is corrosion smaller spool, so that the minimum flow rate adjustable larger.



Pneumatic control valve failure to understand the phenomenon and the reasons to be symptomatic to take measures to resolve it.

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Wednesday, October 27, 2010

Solenoid valve and the structure of knowledge of the Selection Principle (b)


Third, security



Solenoid valve generally not waterproof, when the conditions do not allow selection of waterproof type, the factory can be customized.



The highest calibration solenoid valve Nominal pressure must exceed the maximum pressure within the pipeline, otherwise life will be shortened, or have other unforeseen circumstances.



Corrosive liquids should use the whole stainless steel type, strong corrosive fluid should be selected plastic Wang (SLF) solenoid valve.



Explosive environment must choose the appropriate explosion-proof products.



Fourth, economic



There are many general-purpose solenoid valve can be, but can satisfy the above three points should be chosen based on the most economical products.



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The structure of the principle of the solenoid valve



A: Direct acting solenoid valve



There are normally closed and normally open type two kinds. Type normally closed when power was turned off, when the coil electromagnetic force generated when power to overcome the spring force moving core static core with a direct pull-open valve, media access was; When the coil power disappear when the electromagnetic force, moving iron core in the spring under the force reduction, direct closure of valve port, media access. Simple structure, reliable action, in the zero-pressure and micro-vacuum work. Always the opposite type. If the path is less than the φ6 flow solenoid valve.



Second, step-by-step direct acting solenoid valve



Open the valve using a valve and secondary valve to open even in the one, the main valve and the step-by-step guide so that the electromagnetic valve and differential pressure to open the main valve port directly. When the coil power, the generated electromagnetic force so that core dynamic and static pull-core, I open the valve guide and valve guide I set up on the main valve port, and moving the main spool core together, when the main valve on the Introduction of the pressure chamber through the unloading valve port in the pressure difference and the electromagnetic force at the same time under the spool so that the main upward movement, the main valve to open the flow of media. When the coil power disappear when the electromagnetic force, when the moving core in the self-determination and the role of the spring force to close the valve guide hole, when the media balance the hole in the spool on the main chamber, so that increased pressure on the cavity at this time reduction in the spring and the pressure to close the main valve, drying medium. Reasonable structure, reliable action, zero pressure and reliable when the work. Such as: ZQDF, ZS, 2W, etc..



Third, pilot-type solenoid valve indirectly



This series solenoid valve by the pilot spool valve and main contact channel with the formation of a combination; type normally closed when no power, was switched off. When the coil power, the generated magnetic core so that dynamic and static pull-core, I open the valve guide, the flow of exports of medium, when the main spool to reduce pressure on the cavity, which is lower than the pressure of the import side, the formation of pressure to overcome the spring resistance and the subsequent upward movement, reaching the main valve to open the mouth of the purpose of the flow medium. When the coil power, the magnetic force disappears, the spring force in the core activities under the pilot shut down the mouth reset, when the medium flows from the balance of holes, the main chamber pressure on the spool, and the role of the spring force of the downward movement, Close the main valve port. The principle of open-type is just the opposite. Such as: SLA, DF (φ15 caliber above), ZCZ, etc..


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Principle and types of solenoid valve

History dating back solenoid valve, so far, at home and abroad from the principle of the electromagnetic valve is divided into three categories (ie: direct-acting type, straight moving step by step guide type), while the valve flap from the different structures and materials with the principle of distinction on the branches are divided into six sub-groups (direct-acting diaphragm structure, step by step straight action film structure, the pilot membrane structure, and straight-acting piston structure, step by step straight-acting piston structure, the pilot piston structure).

     Direct Drive Type Solenoid Valve:

     Principle: power, the electromagnetic coil of electromagnetic force to close the piece from the valve seat on the raised, the valve open; power, the electromagnetic force disappears, the spring pressure in the valve seat to close the cases, the valve closes.

     Features: In the vacuum, negative pressure, zero pressure when normal work, but the path is generally not more than 25mm.

     Distribution of Direct Drive Type Solenoid Valve:

     Principle: It is a direct-acting and pilot-style combination of theory, when the entrances and exits when there is no differential pressure, electricity, the electromagnetic force directly to the pilot valve and main valve off the small pieces in turn brought up, the valve to open. When the entrances and exits to start pressure, the electricity, the electromagnetic force pilot a small valve, main valve cavity under the pressure of increasing the cavity pressure drops, thus the use of upward pressure to open the main valve; power, the pilot valve with a spring or to medium pressure to promote off pieces, moving down, so that the valve closed.

     Features: In the zero-pressure or vacuum, high pressure can also be * when the action, but the power of a larger, which calls for horizontal mounting.

     Pilot solenoid valve:

     Principle: electricity, the electromagnetic force the pilot hole opens, the chamber pressure to drop rapidly to form the closure around the lower parts of high pressure, the fluid pressure to promote off pieces of upward movement, the valve open; power, the spring force to pilot hole closed, the inlet pressure chamber through the bypass hole quickly formed around the closed valves on the high-low under the pressure difference, the fluid pressure to promote off pieces of moving down, close the valve.

     Features: limit the scope of a high fluid pressure can be arbitrarily install (need to customize), but must meet the conditions of fluid pressure. ball valve Trunnion Mounted Ball Valve Floating Ball Valve Top Entry Ball Valve ball valve V Type Ball Valve
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Typical type pilot relief valve fault diagnosis and troubleshooting

With the hydraulic system of construction machinery moving in the direction of the development of high-pressure and ultrahigh-pressure pilot relief valve type widely used in construction machinery hydraulic system in the control circuit. In the use of the practice, in order to maximize their effectiveness, the protection control system, accurate and timely diagnosis, rule out the possibility of pilot-type relief valve failure is the key element.



1, control failures, so that the fixed host



Pilot-type relief valve failure, the host can not result in action. According to the phenomenon, analysis of reasons: the pilot valve spool spring break; damping plug hole; pilot valve sealing valve port bad; the main spool, such as card dead. Excluded from the corresponding measure is: to replace or in the break pad Jiaping Department to emergency use; cleansing clear; grinding or the circuit breaker to the emergency use; grinding, cleaning.



2, limit pressure instability



Pilot-type pressure relief valve limits instability, the performance of the hydraulic system for low or high pressure, hydraulic actuator, or inability to move the pipeline, pump body, valve burst.



Caused by this failure include: improper pressure adjustment; pilot valve spool bending or soft spring; oil or dirty oil flows have been impeded. Excluded from the corresponding measures are as follows: re-adjustment; correction, plus pad, or replaced; replacement, cleaning.



Pilot-type pressure relief valve limits the gradual onset of instability for the failure, more than an hour in the reserves more motorized mechanical engineering; pilot-type relief valve for the sudden failure of failure, more than an hour in the reserves with less motor works machinery. After the failure in the end rule out the possibility, should the local system to limit the pressure on the pilot-type pressure relief valve to control re-adjustments. 

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Yee-day life of the valve Innovation













1.3 billion U.S. dollars in cash and 88.9% market share of a valve sufficient to allow any company is only as strong Mammoth - of course you know, I am talking days, Yee valve company, and the ultimate extinction of the mammoth.



Not the same as that day also had the opportunity to save Yee valves themselves, and to prove to the world, it is still the world's most clever companies. (Cast Steel Gate Valve

) Is a valve-day counter-qi Velan, to save his own best example. June 2, Tian-qi valve in the global launch of its own (Cast Steel Gate Valve

), In China, it has been translated into ""--。 This is indeed a lucky name. May Feiyang valve market share in the United States has only 8% (4 years to reach the middle back there too), to the first week of new product releases on the sharp rise to 11.1%, followed by the second weeks, and increased the proportion of 1%.





It's refreshing. Almost ten years, the product just out on a burst of applause Velan has become an almost-hyun, such as the company's patents, and Tian-qi valve products? Sorry, that is too complex to have further comment on the trial for six months.



(Cast Steel Gate Valve

) Does not look the same. This may be the days of the valve core products Yee. Engineers have been informed that those who can give up their traditional strengths, and in accordance with the product as a true to develop. As the product itself, it is everywhere and competitors and to avoid similar tit-for-tat. The most direct change is in (Cast Steel Gate Valve

) Interface, there will be a day to update the background image - Tian-qi valve set up a working group to carefully selected these pictures. Velan or whether it is a large number of imitators, all believed in the "less is more" aesthetic principle, only put in the valve nameplate simple.







"In 5 years ago, we (Cast Steel Gate Valve) In fact, the first generation of the structure and any of the companies are doing almost the valve, and now is different." Tian-qi valve, executive vice president of the Institute said. He used a lot of terminology to explain the new (Cast Steel Gate Valve) apart, put it in simple language, if it is that he believes that qi is a new structure of the valve, and can provide more specific functionality.



Velan used to the users the feeling that some of this unique product. And all point to the unique characteristics of an intimate, in many people easily lose sight of the small corner of the world, Tian-qi valve consistent with its developers have not lost sight of rigorous and often surprises people. Familiar with the idea of Tian-qi valve observers will find that the significance of this change is that of an Internet product, the cost is no longer a core - since the after-sales service are free of charge - replaced by the user experience. The same as the free, users are no longer loyal to the users who can surprise (even if very small), who will be able to win market overnight.



"Dear! Days qi valve is not to give up this game, even though it was such a proposal. To allow these companies to each other to fight for each user calls go, I am sure we will see more in this area of innovation." SEO Savage company and feiyang in velan said after doing a comparison.



This is the day you want the effect of valve-qi. Tian-qi CEO valve products for the new five million U.S. dollars approved the promotion of the cost, he said that he signed all the time shaking hands. But to spend more still to come, Tian-qi valve will be in the next 5 years at least annually to the (Cast Steel Gate Valve) in 5-10% of operating profit. Yee valve to-day in 2008 the income of 2.5 billion U.S. dollars, the Tian-qi valve in the next 5 years (Cast Steel Gate Valve) to invest from 500 to 1300 million U.S. dollars.



Being laughed at for a long time, the day this time Yee valve finally full strength.



Almost from the beginning of the birth of velan, Tian-qi of the large valve, slow, or even the sacred orthodox industrial culture of the industrial sector has become the object of ridicule. A whole decade, the new company from Asia have continued to use some small creative harassment this monster, was a great success, Tian-qi these valves are still only seen as the provocative frivolous. Tian-qi Valve certainly feel strongly that, until his own hand, the market will easily pocket income, or those who can not explain it in the slow years.





Talking about (Cast Steel Gate Valve) is a big success too early, but Powell is right, Tian-qi valve is a major mistake not to enter as soon as possible (Cast Steel Gate Valve) the field. And now, despite the lateness of the hour, day-qi valve disease has finally begun to own the.





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The structure and application of safety valve

Used to prevent the boiler, pressure vessel or piping and other equipment incurred damage due to overpressure valve. When the fluid pressure to protect the body slightly higher than the normal operating pressure to achieve a certain specified value (ie, the valve opening pressure), the safety valve automatically opens, emissions part of the fluid, so that pressure drop. When the pressure drops to a slightly lower than the normal operating pressure of a certain value (that is, the pressure valve back seat), the safety valve closes automatically stop the discharge of fluids and remain sealed. 



 



Safety valve of the valve flap according to the different loading methods are divided into two types of heavy hammer type and spring-loaded (see Figure [safety valve structure]). Hammer-type was divided into direct heavy hammer type and lever-type heavy hammer. Direct heavy hammer-type safety valve is the first use of a safety valve, only a simple low-voltage small-scale equipment (such as domestic pressure cooker), there are still used. Hammer lever-type safety valve structure is simple, load adjustment, reliable, can be used for low-pressure boiler fixed, but great shape, for vibration-sensitive and the use of some disadvantages such as limitations in industry has been rarely used. The most widely used in industry is the spring-loaded safety valve. It can be designed into many kinds of structural patterns in order to meet a variety of application requirements, such as for large displacement, high pressure, high temperature, there is back pressure on the sealing particularly demanding and so on occasions. Figure [safety valve structure] is a very simple structure, a common spring-loaded safety valve. Relief valve is usually by the use of fluid phase behavior were divided into two categories: one category is used for liquids, and import and export of the same size as the opening height of the smaller flap valve; the other is used for steam and gas export size of large on the import of size, valve flap to open a high degree of large, open very quickly. Valve flap valve can be opened by a high degree of emission classification of space conditions.



 



If the poor performance of safety valve, or the selection, improper installation can cause a serious accident or economic losses. Therefore, we must strictly comply with the relevant standards and safety monitoring body of the laws and regulations. After a good safety valve adjustment should be locked or seals, reckless unauthorized personnel is strictly prohibited. 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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How to choose Temperature Control Valve

 With the heating system reform, household heat metering and sub-room temperature control has entered the implementation stage, the temperature control valve is installed in the radiator is already very popular, and with the temperature control valve to achieve sub-room temperature control, both the maximum energy conservation, but also satisfy different user needs for indoor temperature regulation is a good thing benefits the country, but how to select temperature control valve did not fully allow users to grasp, if not the right choice of products, not only to can not meet demand, and may give users an unnecessary economic losses, for which the author according to their own application experience, in which published some of my views, designed to give colleagues and users some useful help.

     Temperature control valve is installed on the water pipes in the radiator temperature regulation (actually flow regulation) of a device. Manual and automatic temperature control valve is divided into two kinds of temperature control valve, automatic temperature control valve is also called Self-operated temperature control valve or automatic thermostat valve, are also referred to as the thermostat valve. Automatic temperature control valve is a temperature sensor Self-executing agencies and special supporting temperature control valve body composition.

     Thermostatic valve valve's structure often straight, angle valve two of the most common two-way valve. Two-way valve is mainly used for two-pipe system or a specially designed a new single-pipe system. In recent years, according to single and double pipe system differences, but also post-graduate output of a single-pipe system specifically applicable to the three links-style temperature control valve and the use of covert installation of suitable single-, double-tube system, a special four-way valve. The four-way valve is currently more common in imported products, such as Italy Jiekemini (GIACOMI-NI) of the four-way valve, which applies not only to all kinds of radiators, and it applies to single and double control systems, but also the ability to to meet the dark filled with a variety of pipe connections.

     Thermostatic valve usually have manual, automatic two kinds, the principle of the valve movements are very different. Manual temperature control valve usually spiral lift spool, rotating handle designed a straight line through the spiral into a spool displacement. And automatic temperature control valve in order to meet the temperature sensor specific self-implementing agency of the straight-line moves, spool movement is usually designed to automatically reset the direct linear displacement, therefore the body under normal circumstances are not interchangeable. But there are also interchangeable, a specially designed valve can be generic, that is, automatic temperature control valve of the valve, attach a suitable manual screw lifting mechanism, can be realized manually, automatic common exchange between the two. This is particularly suitable to improve the situation in China have great practical value, in the present, many projects, developers in order to save the initial investment, first install a valve with automatic temperature control feature along with the spiral movements with special handles, so that both the achieved with 1 / 3 the cost of automatic temperature control valve (the price of basic equivalent to manual temperature control valve) for a manual temperature control valve, and gave the user automatic temperature control in the future to upgrade the space left behind. Even in the imports of this product is also rare in this area of Italy Jiekemini walk in front of the market provides such a range of manual, automatic temperature control valve between a known pairs adjustable temperature control valve, eight stalls setting, the indoor temperature as you set up, extremely convenient. Worthy of the world's larger HVAC valve suppliers. It is this range of manual and automatic temperature control valve of the valve between the particularity of, so choice will be complex, this complexity is not fine for some business people and caused speculation salesman "Fish-in-Water-Belt-Buckle-246.html' target='_blank' class='infotextkey'>fish in" The opportunities. In this I remind that, in the current market there are a lot of automatic temperature control valve suppliers salesman will carry a simple adjustment handle automatic temperature control valve body of the net charge as a dual regulatory function of the temperature control valve to the user recommended, and some users to use such a temperature control valve, which is not very appropriate, there are great risks, so that although the automatic temperature control valve body with a simple adjustment on the handle, but the handle design idea of the automatic temperature control valve in order to meet the valve before the first installation of temporary works for the system adjusted to meet the test of water pressure test only, test the water pressure in the test process is completed, be replaced by automatic temperature control valve valve head, because it temporary, so the easy adjustment of the valve handle on the original loan for a fixed temperature control valve head for helical screw lifting the ordinary use. We all know that simple adjustment handle because of its temporary, one-time, generally use plastic, if used as the final frequency adjustment, the thread wear is very fast, not to mention working in the heating system, the spool up and down movements where there is a certain pressure circumstances, even in the absence of pressure systems, the spool itself alone will greatly speed up the spring pressure on the thread handle wear and tear, so use this product as can be upgraded to automatic temperature control valve of the Manual temperature control valve is not appropriate.

     I studied Italian Jiekemini that can be upgraded to automatic temperature control valve known as the double-adjustable temperature control valve, and other brands the biggest difference is that it is not a temporary one-time adjustment handle products, but specially designed application of the final product has a durable, spiral-shaped teeth thread lift is a special wear-resistant trapezoidal force, pitch up to 4.5mm. There is no worry about long-term use is, of course, temporary use of more no problem. The general regulation of the handle of the temporary borrowing of the thread teeth fixed for the fine thread, thread for general triangular-shaped teeth, the pitch of only 1.5mm. Such temporary handle to rotate three times the displacement of spool 4.5mm pitch with trapezoidal thread lap rather, it means that you will open the valve from the smallest to the largest three times the time required, which often need to adjust the temperature and control valve for regulating the inconvenience is obvious.

     Let's look at automatic temperature control valve, automatic temperature control valve is usually divided into two parts, valve and valve head, valve commonly used method of production of copper casting or hot forging, valve head temperature sensors are generally divided liquid and solid: solid is divided into two kinds: one is the La-system, a hot-memory alloy. Currently on the market the popular media, most of paraffin solid sensor, with little heat memory alloy. Here's the market that are common to the respective valve and valve head to make a simple introduction to automatic temperature control valve for selection for reference.

     Temperature Control Valve Body: Copper casting has the advantage of casting-shaped cavity can be complex products, mold cost less, lower production costs, but the drawback is more than casting defects, materials, compressive strength is poor; In contrast, the copper body by forging dies high value and complexity of forging equipment, production costs are high, but was able to obtain high-strength products, pressure capability is also much higher than the casting, while effectively avoiding casting defects. Thus less complex shape of the body, the professional manufacturers adopt traditional methods of forging body. But there are also some manufacturers to use traditional methods of casting, this requires the user to distinguish carefully. I think the use of a radiator temperature control valve on the valve body are simple, using hot forging is very appropriate.

     In the selection body should pay attention to detail when there is a lot of valve design in order to be more simple, straight-through valve body inlet and outlet in the same axis, so that while the design is simple, but the displacement of spool space will be subject to We, therefore, the general type of valve spool displacement is only 2-3mm. I studied Italian Jiekemini automatic temperature control valve body, its straight-through body design is very unique, guaranteed entry and exit axis in the same circumstances, with the dislocation channel cavity design, effectively increase the displacement of the spool space, makes the spool displacement of up to 4-5mm, which in a recent design of an automatic temperature control valve is rare. Spool displacement increases the more dirty HVAC water is very beneficial, too small spool displacement in a relatively dirty water and scale HVAC serious cases will be very prone to gridlock.

     Thermostatic valve head: Temperature Control Valve head temperature sensor inside the inner filling of liquid and solid media are generally two types of liquid and solid production process due to different manufacturers in general are usually a result of restrictions by the scale of production, often using only one A process to produce liquid or solid valve head, only a few large-scale production of both types of valve head chamber of commerce to facilitate customer choice. As for the difference between the two valve head, I think it should be said in HVAC applications, there is not much difference, if we must point out the difference of the Department, I think in the following aspects: First, different size. Generally speaking, the liquid to achieve the same thermal expansion, a larger displacement of the liquid, so temperature sensor larger, so larger valve heads, with a small proportion of valve sets a little after the lack of coordination, so is preferable to use solid-type valve something more beautiful head. Second, fluid sealing technology to be more complex, the production costs are relatively solid to be a little higher, so sales prices are often higher. 3, the liquid valve head to be a little more sensitive than the solid and this is the only liquid and solid advantages in comparison, but in the HVAC field in terms of a typical large-delay system, this advantage is not much effect. All in all, whether liquid or solid thermostatic valve head, as long as a qualified product, can fully meet the EN215 standard in the time sensitive requirements. I had two Italian Jiekemini medium temperature sensor in nation-building project quality inspection center to compare measurements and found no significant differences.

     It is worth mentioning that the Italian Jiekemini the installation of thermostatic valve head is also very unique, the general temperature control valve installation of the first threaded connections are used, rather Jiekemini they used their own patented technology, fast card pressure-type connections, fast and safe, effective and easy to avoid the loose screw connection manually defects.

     In the body of the connection alive Festival Jiekemini also has its own patent, that is connected to hot on the live festival PTFE self-dense material, to facilitate the installation or hemp rope without wrapping raw materials, effectively increasing installation of efficiency, and achieve an effective seal.

     To sum up, when you want to use temperature control valve should be careful when you transfer the election, so that money can at least make the best choice, whether it is manual, dual-adjustable or automatic temperature control valve, Italy Jie Kemi Nepal can be said is the perfect choice of partner, and complete products, attentive service, all so you can get satisfaction.

     Generally speaking, if the most efficient as a choice for investment principles, without regard to the benefits of energy-saving automatic temperature control valve does not consider future upgrades for automatic temperature control valve, then you can choose a purely manual temperature control valve.

     If, for with very little investment, taking into account the future by the owners themselves to upgrade to automatic temperature control valve, then the optional dual-adjustable temperature control valve, a dual-adjustable thermostatic valve with pure manual temperature control valve is basically the same price.

     If you want to make a one-stop choice, then can choose automatic temperature control valve, generally prices are about three times the manual temperature control valve. 

  

 

ball valve Trunnion Mounted Ball Valve Floating Ball Valve Top Entry Ball Valve 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