Pneumatic valves should be stored in a dry and ventilated room, and both ends of the passage must be blocked. Valves that have been stored for a long time should be inspected regularly to remove dirt. Pneumatic valves should be coated with anti rust oil on the machined surface. In addition, after the installation of pneumatic valves, regular inspections should be carried out, mainly including:
(1) Wear condition of sealing surface; (2) Wear of trapezoidal threads on the valve stem and valve stem nut; (3) Whether the filler is outdated and ineffective, and if there is any damage, it should be replaced in a timely manner; (4) After valve maintenance and assembly, a sealing performance test should be conducted.
The maintenance and upkeep of pneumatic valves during grease injection plays a crucial role in serving the valve in production and operation. Correct, orderly and effective maintenance and upkeep will protect the valve, ensure its normal function, and extend its service life. Valve maintenance may seem simple, but it's actually not. There are often overlooked aspects in work.
Firstly, when injecting grease into pneumatic valves, the issue of the amount of grease injected is often overlooked. After refueling the grease gun, the operator selects the valve and grease connection method before proceeding with the grease injection operation. There are two situations: on the one hand, the amount of grease injected is insufficient, and the sealing surface accelerates wear due to a lack of lubricant. On the other hand, excessive fat injection can cause waste. The reason is that the sealing capacity of different valves is not accurately calculated according to the type and category of pneumatic valves. The sealing capacity can be calculated based on the size and type of the valve, and an appropriate amount of lubricating grease can be injected reasonably.
Secondly, when injecting grease into pneumatic valves, pressure issues are often overlooked. During the grease injection operation, the grease injection pressure exhibits a regular peak valley variation.
Pneumatic valve pressure is too low, seal leakage or failure, pressure is too high, grease injection port is blocked, grease inside the seal hardens, or the sealing ring is locked with the valve ball or valve plate. Usually, when the grease injection pressure is too low, the injected lubricating grease mostly flows into the bottom of the valve chamber, usually occurring in small gate valves. If the grease injection pressure is too high, on the one hand, check the grease injection nozzle and replace it if the grease hole is blocked; On the other hand, lipid hardening requires the use of cleaning fluid, repeated softening of failed sealing grease, and injection of new lubricating grease for replacement. In addition, the sealing model and sealing material also affect the grease injection pressure, and different sealing forms have different grease injection pressures. Generally, the grease injection pressure of hard seals is higher than that of soft seals.
Thirdly, when applying grease to pneumatic valves, pay attention to the issue of the valve being in the on/off position. Ball valves are generally in the open position during maintenance, and in special circumstances, they should be closed for maintenance. Other valves cannot be treated solely as open positions. During maintenance, the gate valve must be in a closed state to ensure that the lubricating grease fills the sealing groove along the sealing ring. If it is opened, the sealing grease will directly fall into the flow channel or valve chamber, causing waste.
Fourthly, when injecting grease into pneumatic valves, the issue of grease injection effect is often overlooked. The pressure, grease injection volume, and switch position are all normal during the grease injection operation. However, to ensure the effectiveness of valve lubrication, it is sometimes necessary to open or close the valve and check the lubrication effect to confirm that the surface of the valve ball or gate is evenly lubricated.
Fifth, when injecting grease, attention should be paid to the issues of valve body drainage and plug pressure relief. After the valve pressure test, the gas and water in the sealing chamber valve chamber increase in pressure due to the increase in environmental temperature. When injecting grease, it is necessary to first discharge and relieve pressure to facilitate the smooth progress of the grease injection work. After grease injection, the air and water in the sealing chamber are fully replaced. Timely release of the pressure in the pneumatic valve chamber also ensures the safety of valve use. After the grease injection is completed, it is necessary to tighten the drain and pressure relief plugs to prevent accidents.
Sixth, when injecting fat, attention should be paid to the issue of even fat production. During normal grease injection, the grease outlet closest to the grease injection port first releases the grease, then to the low point, and finally to the high point, gradually releasing the grease. If it does not follow the rules or does not produce fat, it indicates the existence of blockage, and timely cleaning treatment should be carried out.
Seventh, when injecting grease into pneumatic valves, it is also necessary to observe the issue of the diameter of the pneumatic valve being flush with the sealing ring seat. For example, for a ball valve, if there is an opening interference, the opening limiter can be adjusted inward to confirm that the diameter is straight and then locked. Adjusting the limit should not only focus on opening or closing one position, but also consider the overall situation. If the opening position is flush and cannot be closed in place, it will cause the pneumatic valve to not close tightly. Similarly, when adjusting the closing position, it is also necessary to consider adjusting the opening position accordingly. Ensure the right angle travel of the valve.
Eighth, after grease injection, be sure to seal the grease injection port properly. Avoid impurities entering or lipid oxidation at the grease injection port, and apply anti rust grease to the cover to avoid rusting. So that it can be applied in the next operation.
Ninth, when injecting grease into pneumatic valves, specific issues should also be considered in the future sequential transportation of oil products. Considering the different qualities of diesel and gasoline, the ability of gasoline to wash and decompose should be considered. In the future valve operation, when encountering gasoline section operation, timely supplement lubricating grease to prevent wear and tear.
When applying grease, do not ignore the grease on the valve stem. There is a sliding shaft sleeve or packing at the valve shaft, and it is also necessary to maintain lubrication to reduce friction resistance during operation. If lubrication cannot be ensured, the torque of the worn parts will increase during electric operation, and the switch will be laborious during manual operation.
Eleventh, some ball valve bodies are marked with arrows. If there is no English FIOW script attached, it indicates the direction of the sealing seat and does not serve as a reference for the flow direction of the medium. The valve's self discharge direction is opposite. Normally, a double seat sealed ball valve has a bidirectional flow direction.
When maintaining pneumatic valves, attention should also be paid to the issue of water ingress in the electric actuator and its transmission mechanism. Especially the rainwater that seeps in during the rainy season. One is to rust the transmission mechanism or shaft sleeve, and the other is to freeze in winter. Causing excessive torque during the operation of the electric valve and damaging the transmission components can cause the motor to be unloaded or the overtorque protection to trip, making it impossible to achieve electric operation. The transmission components are damaged and manual operation is not possible. After the overtorque protection action, manual operation of the pneumatic valve also cannot be opened or closed. If forcibly operated, it will damage the internal alloy components.
