In the pneumatic system different period ,it will happen many faults.We can sort out three types period:Initial faults,sudden faults and aging faults.
Initial failure refers to the failure occurred in commissioning stage and within two or three months after starting operation. The causes are:
1) Poor processing and assembly of components, such as unqualified grinding of inner holes of components, incomplete removal of burrs of parts, unclean installation, wrong and reverse assembly of parts, poor centering during assembly, improper tightening torque of fastening screws and unqualified material of parts
Poor quality of outsourced parts (such as seal ring and spring).
2) Incorrect design, improper material selection of parts and unreasonable processing requirements during component design. Inadequate understanding of the characteristics, performance and functions of the components, resulting in improper selection of components during loop design. The designed air handling system cannot meet the requirements of pneumatic components and systems. Loop design error.
3) When the installation is not in accordance with the requirements, the purging in the components and pipes is not clean, so the dust, sealing material fragments and other impurities are mixed, causing the pneumatic system failure. Unbalanced load during cylinder installation. No effective measures have been taken for anti-loosening and anti-vibration of pipes. 4) Improper maintenance management, such as failure to discharge condensate water in time, failure to supply oil to atomizer in time, etc.
Sudden failure
Sudden failure of the system during stable operation is called emergency failure. For example, the oil cup and water cup are made of polycarbonate. If they work in the mist of organic solvent, they may break suddenly; The residual impurities in the air or pipeline mix into the components, and the relative moving parts are stuck suddenly; Sudden fracture of bullet, sudden burst of hose and sudden burning of electromagnetic coil; Circuit malfunction caused by sudden power failure, etc.
Some sudden failures are omens. If impurities and moisture appear in the discharged air, it indicates that the filter has failed. Find out the cause in time and remove it. Do not cause sudden failures. However, some sudden failures are unpredictable, so only safety protection measures can be taken for prevention, or some vulnerable spare parts can be prepared for timely replacement of failed components.
Aging fault
The failure of individual or few components after reaching the service life is called aging failure. It is possible to roughly predict the occurrence period of aging failure by referring to the production date, date of use, frequency of use and some existing signs of components in the system, such as abnormal sound and increasingly serious leakage.
In order to derive the true cause of the failure from the various possible common failures, reasoning principles and methods can be used. The diagram shows the logic logic reasoning diagram for failure diagnosis of valve control cylinder failure
The solenoid valve failure is divided into two parts: one is that the solenoid pilot valve does not reverse, and the other is that the main valve does not reverse.
Five causes for solenoid valve pilot valve not reversing:
·The power is not connected: the possible reason is that the switch is not closed or the wire connector falls off
·Insufficient voltage: the overall voltage of the area is insufficient due to the large environmental factors in the plant area
·The moving iron core is stuck: the iron core is rusted or the valve is blocked by foreign matters
·The moving iron core does not reset: blocked by foreign matters, rusted and possibly broken spring
·The coil is burned: the voltage is too high, the ambient temperature is too high, the operating frequency is too high, the AC electromagnetic iron core is stuck, two electromagnets of the double electric control solenoid valve are energized at the same time and no interlocking circuit is set.
The main reason for the main valve not reversing is that the valve core cannot act or the reversing is not in place. The causes include wrong connection of pipe orifice, too low operating pressure, poor lubrication, foreign matter blockage, damage of sealing element, spring and valve core bushing.
Cylinder failure is characterized by air leakage, excessive load, speed control failure and excessive friction resistance
Excessive load may be caused by excessive external load of cylinder, lateral load and non-coaxial installation.
Speed control failure may be caused by throttle valve opening too small or not open
Excessive friction resistance may be caused by blocking of piston and cylinder barrel due to improper lubrication, poor quality of cylinder barrel and easy corrosion, excessive compression of seal ring and existence of foreign matters. Or the piston rod and cylinder head are stuck due to improper lubrication, foreign matter blockage, deformed sealing ring, deformed piston rod or rust.
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Cylinder Failure Troubleshooting Solutions |
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Failure Symptoms |
Failure Analysis |
Failure Classification |
Failure Elimination |
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Cylinder has no output force |
1.Internal air leakage in the cylinder / Piston seal leakage |
Seal failure |
Replace the piston seal of the cylinder |
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2.Insufficient air supply pressure |
Misoperation |
Increase air pressure, shorten air pipe length |
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3.Air leakage at cylinder fittings |
Fitting failure |
Re-cut and reinstall fittings with burr-free ends |
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How to AvoidThe air pipe and fittings should be cleaned and blown before use; compressed air must be filtered before use. |
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After passing through longer pipelines, there will be air pressure loss. Cylinders should be equipped with a lubricator or FRL unit to ensure sufficient air pressure, and further purify the air source.
If the pipe length cannot be shortened and the air pressure is insufficient, a booster valve can be used to compensate for the loss.
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Before using the cylinder, check all sealing parts to ensure there is no obvious air leakage in the pneumatic system. |
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The resistance of the cylinder piston increases, after running for a period of time the cylinder heats up. |
Insufficient piston lubrication |
Operational error |
Lubricate with an oil mist lubricator |
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How to Avoid：Cylinders are pre-lubricated before leaving the factory and can be used without oil. However, once oil mist lubrication is applied, it must not be stopped, as the oil mist will wash away the internal lubricant. After stopping the oil supply, the cylinder will be left in a non-lubricated state. Similarly, if the compressed air contains water, it will also wash away the lubricant. Therefore, an oil mist lubricator should be used to maintain lubrication. |
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After carrying a lateral load for a period of time, the cylinder experiences increased operating resistance and weak output. |
Lateral load causes cylinder barrel damage. After disassembly, single-sided or double-sided scratches and wear can be observed on the cylinder barrel. |
Operational error, mechanical damage, sealing failure |
Replace the cylinder barrel and seals |
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How to Avoid：Cylinders without lateral load capacity must not be subjected to any form of lateral load. If the design cannot avoid it, a guide rail should be installed for the load to prevent the cylinder from directly bearing the lateral load. |
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The cylinder cannot fully extend, and operation encounters resistance. |
The cylinder barrel has been damaged due to impact, preventing the piston from passing through the damaged area. |
Mechanical damage |
Replace the cylinder barrel, and if necessary, replace the piston seals. |
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How to Avoid：During storage and transportation, cylinders should be protected from impact. In equipment design and operation, potential collisions should be avoided. If the cylinder barrel is already damaged, do not force the cylinder to operate, otherwise the piston and seals may suffer secondary damage. |
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The cylinder retracts weakly, while extension is normal. |
1.Seal failure between the front end cap and the cylinder barrel |
Seal failure |
Replace the sealing components |
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2.Dust seal failure at the rod exit of the front end cap |
Seal failure |
Replace the sealing components |
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How to Avoid：Do not disassemble the cylinder’s end cap and barrel without authorization. Avoid using the cylinder in harsh environments. Welding slag, iron chips, wood debris, glue, dust, and other contaminants can enter along with the piston rod movement, wearing out the dust seals, which may result in seal damage, failure, and air leakage.
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Cylinder cushioning issue |
1.For adjustable cylinders, the piston cushioning sleeve may prevent the piston from reaching the cushioning area, resulting in no cushioning. |
Operational error |
Not a fault |
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2.Leakage at the needle valve due to needle valve sealing failure. |
Seal ring failure |
Replace needle valve seal ring |
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3.Damage to the cylinder cushioning seal ring. |
Seal ring failure |
Replace cylinder cushioning seal ring |
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How to Avoid：Adjust the stroke accordingly. If adjustment is not possible, cushioning can be disabled.If cushioning is necessary, an external hydraulic cushion or other external cushioning device can be added. |
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In order to reduce the above faults, we should pay more attention to selecting high-quality solenoid valves and cylinders when selecting pneumatic components. High-quality components not only reduce the failure rate, but also improve the stability and service life of the system.
Choosing a professional solenoid valve or cylinder manufacturer offers several key advantages:
Production strength and technical support: professional manufacturers have powerful processing equipment and perfect production process, and are equipped with experienced technical teams to ensure stable product quality and performance.
Rich product experience: Enterprises engaged in the pneumatic industry for a long time have accumulated rich product experience. For example, a professional solenoid valve manufacturer usually can provide a complete valve product range, including the full range of 3V and 4V solenoid valves，4A air control valve , as well as various mechanical valves, reciprocating valves, etc., with excellent manufacturing.
Matching of parts and components with the supply chain: the solenoid valve design involves a large number of spare parts, such as: mechanical button head size and color, dust cover size and screws of various sizes, etc. When developing new products, professional manufacturers can quickly and accurately match suppliers to ensure that customized products are produced efficiently and accurately.
Speeding up the manufacturing and delivery cycle: Due to rich experience in product development, professional manufacturers can accelerate the product manufacturing cycle and delivery cycle to meet the industrial production requirements.
Perfect after-sales service: when customers encounter problems, the manufacturer's quality inspection and technical team can quickly determine the root cause of the problem, propose improvement plans, and ensure that the problem is solved in time.
OLK has become a reliable brand of high quality pneumatic solenoid valves. Through 22 years of industry deepening, OLK team provide customers with durable, efficient and innovative solutions to meet diversified industrial needs and make the system operate more stably and reliably.
