What are the common valve failures and their solutions?

Valves are widely used in industrial production, and their failure will seriously affect the normal operation of the system. This article will discuss common types of valve failures and introduce corresponding treatment methods in detail. Whether you are a maintenance engineer, designer, or an individual interested in valve failure, this article can provide you with valuable information to help you identify, diagnose, and resolve valve failures to ensure reliable operation.

1. What are the common valve faults and their solutions?

1. Valve body leakage:

Cause:

1. The valve body has blisters or cracks;

2. The valve body is cracked during repair welding

Treatment:

1. Polish the suspected cracks, Use 4% nitric acid solution to etch and reveal any cracks;

2. Excavate and repair the cracks.

2. The valve stem and its matching nut thread are damaged or the valve stem head is broken or the valve stem is bent:

Reasons:

1. Improper operation, excessive force on the switch, failure of the limit device, and failure of the over-torque protection . ;

2. The thread fit is too loose or too tight;

3. Too many operations and the service life is too long

Treatment:

1. Improve the operation and do not use too much force; check the limit device and check the excessive torque Protection device;

2. Choose appropriate materials and assembly tolerances meet the requirements;

3. Replace spare parts

3. Leakage on the valve cover joint surface: Reason:

1. The bolt tightening force is not enough or the tightening force is biased;

2. The gasket does not meet the requirements or the gasket is damaged;

3. The joint surface is defective

Treatment:

1. Retighten the bolts or make the door cover flange gap consistent;

2. Replace the gasket;

3. Disassemble and repair the sealing surface of the door cover

4. Internal leakage of the valve:

Reasons:

1. Loose closing;

2. Damage to the joint surface;

3. The gap between the valve core and the valve stem is too large, causing the valve to The core is sagging or has poor contact;

4. The sealing material is poor or the valve core is stuck.

Treatment:

1. Improve the operation, reopen or close;

2. Disassemble the valve, and re-grind the sealing surface of the valve core and valve seat;

3. Adjust the gap between the valve core and the valve stem or replace the valve disc;

4. Disassemble the valve to eliminate jamming;

5. Replace or overlay the sealing ring

5. The valve core and valve stem are separated, causing switch failure:

Reason:

1. Improper repair;

2 . The joint between the valve core and the valve stem is corroded;

3. The switch is applied with excessive force, causing damage to the joint between the valve core and the valve stem;

4. The valve core backstop gasket is loose and the connection part is worn

Treatment :

1. Pay attention to inspections during maintenance;

2. Replace the door rod with corrosion-resistant material;

3. Do not open or close the valve forcefully, or continue to open the valve after fully opening it;

4. Check and replace damaged spare parts

6. Cracks in the valve core and valve seat:

Reasons:

1. Poor quality of surfacing on the joint surface;

2. Large temperature difference on both sides of the valve Treatment:

Repair welding of the cracked area according to regulations Heat treated, polished and ground.

7. The valve stem does not lift or switch properly:

Reasons:

1. It is closed too tightly when it is cold and swells when heated or too tight after it is fully opened;

2. The packing is pressed too tightly;

3. The valve stem gap is too small and swells to death;

4. The valve stem and the nut are too tight, or the mating thread is damaged;

5. The packing gland is biased;

6. The door stem is bent;

7. The medium temperature is too high, the lubrication is poor, and the valve stem is severely rusted.

Treatment:

1. After heating the valve body, slowly try to open it or open it fully and tighten it and then close it slightly;

2. Slightly loosen the packing. Test open after gland;

3. Increase the valve stem gap appropriately;

4. Replace the valve stem and nut;

5. Readjust the packing gland bolts;

6. Straighten the door stem or replace it ;

7. The door pole uses pure graphite powder as lubricant

8. Packing leakage:

Reason:

1. The packing material is wrong;

2. The packing gland is not pressed tightly or is biased;

3 .The method of adding packing is wrong;

4. Damage to the valve stem surface

Treatment:

1. Select the packing correctly;

2. Check and adjust the packing gland to prevent pressure deviation;

3. Press the correct button Method: Add packing;

4. Repair or replace the valve stem

Article reference: Eight common valve faults and solutions - China Valve Enterprise Style Platform

2. Common computer host faults and solutions?

First, the problem of leakage. We often get electric shock when touching the host. This is because during the power supply process, some components form a path with the chassis, causing leakage. A common solution is to first check whether there is a quality problem with the power supply. If there is a problem, quickly replace the power supply with a new one. Secondly, if it is not a quality problem, you can connect a ground wire to complete the discharge work.

Second, there is a serious smell inside the case. Don't take it lightly, be sure to carefully check each component in the chassis. If there is any burnt phenomenon, it is mostly caused by a power supply problem, because too high or too low voltage will cause the components to burn. Use a multimeter to measure the power supply pins. If there is a problem with the power supply voltage, replace it in time.

Third, it cannot be turned on normally. After booting, only the CPU fan runs. And it often crashes, and the software part has been checked and there is no problem. At this time, it is necessary to check whether there is a problem with the power supply. Similarly, use a multimeter to check whether the voltage and other parameters of its pins are up to standard. If there is a problem, it is best to replace it in time to avoid secondary damage to other components.

Fourthly, pressing the power button will not shut down the device, but selecting the shutdown button in the menu will shut down the device. This is a CMOS setting problem. Just enter the CMOS and select the BIOS option to set it.

Fifth, there is sparking behind the power supply of the host computer. During this period of time, this problem always occurred in our computer room, and after inspection, there was no problem with the power supply. Later, after inspection, it turned out to be a problem with the power cord. The quality of the power cord sometimes directly affects the host power supply. The only solution is to buy new ones, and the price is about 10 yuan a piece.

Sixth, start the fire in the host. It is generally difficult for other components in the host to spark. Most of the reasons occur in the power supply, which is caused by short circuits in the internal components of the power supply. The solution is to send it to a repair shop or replace it with a new one.

Seventh, the fan inside the chassis rotates too loudly. Turn on the host and check. There is basically no sound from the CPU fan and graphics card fan. The sound is undoubtedly coming from the power supply. The solution is to disassemble the power supply and clean the dust on the power supply fan. This problem can basically be solved.

3. What are the common troubleshooting methods for computer keyboards?

1. It’s all the fault of foodies

In the hands of foodies, the keyboard often becomes a collection place for food residues. Some larger food residues, such as melon seed shells, and some sticky objects may fall into the gaps between the keyboards. As a result, the keyboard gets stuck after being pressed and cannot rebound normally. The keys need to be pulled out to reset.

Solution:

This kind of stuck key is also very simple to deal with. After pulling off the keycap and cleaning up the debris at the bottom of the keyboard, the problem can be solved.

2. Unavoidable aging

For mechanical keyboards, aging keys are mainly caused by two reasons. One is that the springs inside the mechanical keyboard are corroded, which leads to a reduction in elasticity. This is true in the south, especially in areas with high air humidity. is a frequently encountered problem. After three to five years of use, mechanical keyboards are prone to key jams caused by spring corrosion.

Secondly, there is the problem of friction and aging between the keyboard cover and the axis core. During the use of a mechanical keyboard, there will be wear and aging between the key cover and the axis core. When the wear and tear reaches a certain level, the friction will increase. In this way, the spring cannot pop out the shaft core smoothly, causing the key to jam.

Solution:

If the above-mentioned aging key jamming problem only exists in a few keys, you can solve it by replacing the spring, adding lubricant to the shaft core, or even replacing the keys.

3. Liquid corrosion is the culprit

The keyboard only reacts occasionally when you tap the keyboard continuously, and this phenomenon tends to become more and more serious. In the early stage, the keys occasionally fail, and in the later stage, the keys only occasionally work or even fail completely. .

When mechanical keyboards have this problem, it is most likely caused by water intrusion: in terms of waterproofing, mechanical keyboards are inherently weak. The keys are not sealed. It is difficult for mid-to-low-end products to have waterproof structures. In this case, a glass of water may kill them. keyboard, and cola, coffee, and juice containing sugar and phosphates are even more powerful.

Solution:

For buttons that are not too severely corroded, you only need to spray a rust-removing lubricant like Philips Water into the disassembled buttons to solve the problem. If the rust is severe, the key body needs to be replaced.

4. Welding and desoldering: common problems of low-cost mechanical keyboards

Nowadays, the workmanship of some low-priced mechanical keyboards is not excellent. They not only use unknown domestic shafts, but also have no bottom iron plate and the circuit board is relatively thin. , even the welding process is not too good.

Solution:

Such a problem is not difficult to solve. Just carefully observe the solder joints under the unresponsive button to see if there is desoldering and perform repair welding. If the copper foil of the circuit board is cracked , which is more troublesome to observe.

However, in this case, most of the problems occur when several keys are unresponsive at the same time. As long as you find the common copper foil of these keys and use a multimeter, you can quickly find the breaking point of the copper foil, and then use a Simply connect the solder joints with a jumper to solve the problem.

4. Common faults of computerized pipe cutting machines and their solutions?

1. The alarm cannot be started at startup: Different stops of the upper cutter will cause the power distance to hit, resulting in an overload alarm. At this time, you need to turn off the power and adjust the screws of the cutter slide, and then restart the equipment.

2. Common alarm faults: Intermittent beeping will occur when the batch is paused. When the batch pause time passes, the buzzer will automatically stop beeping.

3. The length of the cut tubes is inconsistent: the pressing wheel is not adjusted properly. Materials with high elasticity should have low pressure, and materials with low elasticity should have high pressure.

4. The material cannot be fed out: the slide is too loose and the upper knife stops at a too low position, which blocks the material feeding.

5. How to deal with common faults of liquid level gauge?

1. The float level gauge has no liquid level display or the display is minimal

This fault means that the liquid level of the process is normal, but the instrument has no display or the display is minimal, or even displays a negative value. Sewage can be drained to check whether there is scale or blockage in the sampling valves and sampling pipelines; the blockage can be cleared by cleaning and blowing. If the sampling valve is seriously blocked or leaks, it must be replaced. The inside of the outer float can be inspected. If the float is broken or there is material hanging on the float, the liquid level display will become low or appear below zero.

If there is an open circuit in the transmitter connection circuit, abnormal power supply, or damage to the transmitter's amplification board or display board, the transmitter will have no display, or the output current will decrease, and the display does not match the output current. Replacing the circuit board requires resetting the parameters.

The transmitter has no current output, check whether the wiring is correct; observe whether there is a display on the LCD meter. If there is a display but no output current, the output tube may be damaged. You can replace the circuit board to confirm. Damage to the EEPROM will cause the loss of instrument calibration data and may also cause a no-current output failure.

2. The float level gauge displays the maximum liquid level

, which can be checked mechanically first and then electrically. Corrosion, crystallization, and sediment adhesion of the process medium, large changes in the density of the process medium, stuck or falling floats, and unsatisfactory installation verticality will cause the liquid level display to be maximized; the mechanical part is in direct contact with the process medium, resulting in a high failure rate in the electrical part. If the pontoon is stuck, you can disassemble it or clean the dirt on the pontoon. If the pontoon falls off, you need to disassemble and hang the pontoon and adjust it before it can be used. The density of the process medium changes greatly, and the medium temperature exceeds the design value too much. After consultation with the process, it must be recalculated and adjusted according to the new range.

Make sure there is no problem with the mechanical part. You can check the power supply, zero point, and range of the transmitter. Whether the zero point drifts or is too high, and whether the range setting is correct. You can measure the output current of the transmitter to judge the safety of the transmitter. Check whether the grid is normal.

3. The liquid level display of the float level gauge is too high or too low. When there is a deviation in the liquid level display, use the communicator to check whether the parameter settings of the transmitter are correct. There is a deviation in the display of the float level gauge. , it is often related to the measured medium. The density change of the medium is greatly different from the design and set value, and the liquid level display value will be inaccurate. Some gases, gasoline and other media contain high sulfur content, which can easily crystallize or agglomerate at the float boom, causing measurement inaccuracies.

The signal circuit causes the DCS liquid level display to be too high or too low. The phenomenon is that the display of the float level gauge and the local liquid level gauge are corresponding, but the DCS liquid level display deviates greatly. There are many such faults. It is due to the water entering the terminals and junction box terminals of the signal line that the insulation resistance of the signal line to the ground decreases, or the insulation resistance between the positive and negative electrodes of the signal line decreases; it seriously causes the signal line to be grounded and the short circuit fault between the signal lines; Signal shunting will make the DCS display lower than the field instrument, and the introduction of ground current interference will make the DCS display higher. Faults often occur during the rainy season or after general cleaning. If the terminal box or junction box is not properly sealed, it is easy for water to enter. You can wrap it with plastic sheeting or seal it with explosion-proof cement to make it waterproof.

4. The liquid level display of the float level gauge fluctuates

Observe the historical record curve of the measured liquid level to see what kind of fluctuation it is. Slow fluctuation may be caused by medium fluctuation or mechanical failure of the float. The float immersed in the medium will have a certain degree of inertia and damping, so the fluctuations are unlikely to change suddenly. If there are large fluctuations or sudden fluctuations, most of them are caused by problems with the circuit or signal lines. For example, the wiring of the transmitter is in poor contact or loose. You can judge by measuring the resistance value of the wires in sections. You should also check whether the instrument is affected by electromagnetic interference. interference.

The process liquid level often fluctuates, which can be overcome by increasing the damping time and filtering. If the measured liquid level fluctuates greatly, consider configuring a anti-surge pipe. It is necessary to understand the nature of the medium to be measured in the process. For example, a company uses a float level meter to measure the liquid level of the condenser. The medium is Freon, and the liquid level display often fluctuates. Later, it is found that the cause of the fluctuation is that there are too many bubbles in Freon, causing the float to Fluctuation; it can be seen that production conditions have a great impact on instrument measurement. Therefore, when judging and handling faults, we should not just focus on the instrument, but also consider the impact of the process. There are problems with the design and selection. The calculated density of the float is incorrect and the installation position is not good. The properties of the measured medium are inconsistent with the design values. The process pressure and flow fluctuations are too large, which may cause fluctuations in the liquid level display.

The output current of the transmitter is unstable. Check the measurement circuit of the transmitter, check whether the voltage on the transmitter terminals is stable, and check whether the transmitter connection line has poor contact or grounding. Use the communicator to make the transmitter output a fixed current such as 4mA or 20mA to determine whether there is a problem with the transmitter or safety barrier and deal with it accordingly.

There is a fault in the mechanical part. For example, the working performance of the torque tube is unstable, and the float hook is damaged, which will make the output current of the instrument unstable, cause large fluctuations in the range near zero, and also affect the linearity of the instrument. Mechanical failure can only be determined by disassembly and inspection.

5. The liquid level of the float level gauge changes slowly

When the process liquid level changes, the meter display also changes, but the change speed is inconsistent with the actual liquid level. You can check whether the sampling valve and sampling pipe are clogged by draining the sewage; the liquid level changes slowly Many reasons are due to attachments on the float or friction between the float and the outer sleeve; steam can be used to purge it regularly, or heat tracing can be added to the outer sleeve of the instrument.

If the gas and liquid phase sampling pipes or sampling valves of the liquid level meter are clogged, especially when the gas phase pipeline is clogged, it will cause the pressure imbalance between the measuring cylinder and the upper part of the container, and the upper part of the float will be pressurized, causing the float to move slowly and causing the liquid level display to change slowly. . If the opening of the sampling valve is too small, the liquid level will change slowly and deviate from the actual liquid level. This failure will be more prominent when the gas phase pipe is clogged.

6. The liquid level display of the float level gauge does not change

The process liquid level is normal and changes, but the liquid level display does not change for a long time. The DCS liquid level trend curve is a straight line. The problem can be found through sewage discharge. It can be knocked when sewage is discharged. The outer float, sometimes the float is stuck, and the float collides with the outer float. It is possible to return to normal by knocking the outer float; if there is no problem with the mechanical part, you should find the cause on the circuit of the transmitter, the display panel of the transmitter or If there is a problem with the amplifier board, spare parts can be used to determine the fault. Replacing the circuit board requires re-entering parameters and making linear adjustments.

If the gas or liquid phase sampling pipe or sampling valve of the liquid level meter is blocked, or the opening of the sampling valve is too small, the measured liquid level will not change for a long time, and the liquid level trend curve is a straight line, especially the liquid phase sampling pipe. It is often clogged by impurities in the pipeline, and the probability of blockage is higher when the pipeline is long. If the gas phase sampling pipe or sampling valve is blocked, and the opening of the sampling valve is too small, the liquid level will change slowly and deviate from the actual liquid level.

The measuring medium is easy to crystallize, or changes in temperature and pressure cause the material to crystallize, and the crystallized material will float. A stuck torque tube or hook will cause the liquid level display to remain unchanged. This type of fault can only be dismantled and repaired. There is no good way to completely eliminate it. However, some measures can be taken to reduce the impact, such as wrapping the outer pontoon with insulation material to reduce the impact of external temperature and eliminate the crystallization of volatile matter in the pontoon. Coking phenomenon; if the measured medium can be blown with steam or hot air, the purging method can be used to reduce crystallization and coking phenomena. When you are still stuck with crystallization problems after taking the above measures, you can only consider using other measurement methods.

6. How to deal with common problems of poppet valve?

How to deal with single-machine dust collector:

　①Add a set of oil-water separators, one is on and the other is in standby. When it is found that the filter element is dirty, you can replace it with another set and clean the dirty set;

　　② In addition to replacing the poppet valve seal in time, the following measures should also be taken: Adjust the poppet valve air supply pressure to 0.25~ Between 0.5MPa, each poppet valve can operate within the specified time. The pressure should not be too high, otherwise it will easily cause the cylinder seal to age. When the air leakage point increases, the air supply pressure can be appropriately increased; oil and water separation The oil supply speed should not be too small to avoid oil loss. In addition, add a certain amount of grease to the valve stem of the lifting cylinder.

7. How to deal with common faults of Huawei inverters?

1. Initial startup settings of the inverter (the fault phenomenon is usually no alarm, no startup and frequent alarms about abnormal grid voltage) 1. V1 machines with screens (8-28KTL) 2. V2 and above machines without screens (33KTL and above)

2. Data acquisition login password and initial power-on settings 1. V1 has a screen data collector (SmartLogger1000) 2. V2 does not have a screen data collector (SmartLogger2000)

3. Basic troubleshooting and processing skills for insulation resistance (residual current) alarms 1 , V1 machine with screen (8-28KTL) 2. V2 and above machine without screen (33KTL and above model) 3. Huxiao SUN2000L machine (

8. How to deal with common faults of dental handpieces?

Fault 1: Water supply occurs Undesirable phenomena.

　Including: (1) Insufficient water supply; (2) Uneven water supply; (3) Water supply is not mist-like; (4) No water comes out at all.

　 Check the parts where the water is blocked:

　 (1) Pipeline: Remove the turbine handpiece and check whether the appropriate amount of water flows out of the pipe. If no water flows out, there may be a problem with the water pipe or the water supply system of the integrated treatment unit (poor contact or malfunction, and insufficient water pressure in the water source).

　(2) Interface: Connect the interface wire for test operation. If there is no appropriate amount of water flowing out, it indicates that there is a problem at the interface (scale or the like has blocked the water supply system or the interface is loose, causing insufficient pressure)

　) Mobile phone body: After removing the shaft core from the turbine, install the interface and run it. If the appropriate amount of water does not flow out, there is a problem within the turbine handpiece body (the water supply hole is clogged with dirt or the turbine handpiece

) The water supply system is blocked).

　　(4) Axis core: If the water supply in the above three items flows out normally, it is a problem with the axis core (the water supply nozzle is clogged).

　Fault 2: The axis core water spout is clogged.

　Solution. Method:

　(1) Remove the end cover and take out the shaft core.

　(2) Remove the nozzle cleaning needle from behind the brush and insert the needle straight into the water nozzle.

　(3) The nozzle cleaning needle is required. Insert it into the upper groove (the needle passes through the air jet groove). Use a special brush to clean the dust from this part.

　　(4) Use a three-purpose gun from the needle side.

　　(5) Blow the shaft clean. When the core is installed on the machine head, be sure to install the O-type sealing ring correctly.

　Fault 3: The needle is easy to fall off, the needle cannot be pulled out, and the axis vibrates.

　(1) When selecting the needle. , you must confirm the allowable speed range specified by the turning needle manufacturer, otherwise the turning needle will easily fall off when the cutting load is greater than the clamping force of the chuck

　　 (2) The mini machine head should use a short-handled turning needle and a long-handling turning needle. Easy to fall off

　　(3)不可使用磨損變細的車針、彎曲的車針、缺刃的車針，否則會影響軸承的耐久性。

　　(4)車針安裝後必須拉拔車針，確認確實已裝牢固，如果未插到深處，插的太淺，會造成車針飛出的危險。

　　故障四:手機不轉或轉速慢。

　　解決方法:(1)手機頭碰撞、跌落變形，使風輪運轉受到阻力。只要用合適的工具讓其復原，就能讓風輪運轉靈活。

(2)軸承缺油潤滑。加手機潤滑油潤滑即可。

(3)軸承損壞。只要更換相同型號的軸承即可。

(4)氣壓低。達不到2.0－2.5kgf/cm2，調整氣壓，使氣壓穩定在2.0－2.5kgf/cm2，轉速就會

九、銑床常見故障及處理方法？

銑床常見故障包括刀具磨損、零件鬆動、傳動系統故障等。處理方法包括更換刀具、緊固鬆動零件、檢查和修理傳動系統等。

在維護銑床時，需要經常進行清潔和潤滑，以確保設備的正常運作和延長使用壽命。同時，定期檢查設備的各項指標和參數，及時發現故障並進行處理。

十、製磚機常見故障和處理方法？

製磚機使用常見故障：

1、系統產生噪音：

產生噪音的原因主要是因為液壓泵吸孔，因為液壓泵進油口漏氣，吸油管路太長，管徑太小，油管吸油面太低，液壓泵吸油口太高，濾油器變形，流通面積小，油箱不透氣，油液黏度太大等。

2、液壓泵的故障：

是因為齒輪泵齒形精度低，導致液壓泵軸的隙磨損增大，再加上輸油量不足，從而導致液壓泵出現故障，溢流閥失靈，雜質沉澱物堵塞管道，導致彈簧變形損壞。

3、機械振動：

這主要是因為油管相互或跟支撐壁碰撞，油管振動，液壓泵和電動機安裝不同心，溢流閥振動等引起的;針對油泵和馬達的流程脈動，困油現象沒有及時消除，葉片或活塞就會卡死，從而出現噪音和振動，這個時候拆開清洗並檢查製造質量，對於不符合要求的零件，需要及時修理和更換。

當吸油路當中有氣體存在的時候就會出現嚴重的噪音，這個時候需要具有針對性的緊固每個結合面以及連接管道的螺絲，接頭以及接口螺母，清洗濾油器，補充油箱內的油液到油標的位置，讓濾油器浸沒在油液裡面，為了預防空氣混入系統當中，大家需要及時的把混入系統當中的空氣排出。

4、液壓系統壓力不足

出現故障的主要原因就是系統的壓力油路和會有路短接，或者是有非常嚴重的洩漏情況，也可能是油箱裡面的油根本沒有進入液壓系統或者電動馬達功率不足等。

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