Introduce the common problems of FESTO solenoid valve blockage logistics separately
When the fluid velocity of the FESTO solenoid valve reaches the speed of sound inside the valve or downstream pipeline during the process, gas and vapor will block the flow. When the fluid inside the valve reaches the throttling zone, the pressure decreases and the specific volume increases until it reaches the speed of sound. When there is a blockage in the logistics, the flow rate is limited to the flow that can pass through at that point, and the flow rate cannot be increased unless there is a change in operation.
The presence of vapor bubbles caused by air pockets or flash evaporation in liquid operation of FESTO solenoid valves significantly increases the fluid specific volume, and the rate of increase is faster than the pressure difference. Under the condition of liquid blockage in logistics, if the upstream pressure remains constant, reducing the downstream pressure does not increase the flow rate. In gas operation, the flow velocity in any part of the valve or downstream pipeline is limited to Mach 1 (speed of sound). Therefore, the flow rate of gas is limited to the flow rate at which the valve spool or downstream pipeline reaches the speed of sound.
Cavitation is a phenomenon that can only occur during liquid handling. When observing bubbles generated by ship propellers, it is found that these bubbles seem to reduce the speed of the ship and cause actual damage to the propellers.
Whenever atmospheric pressure equals liquid vapor pressure, bubbles are generated. Obviously, when the liquid is heated and the vapor pressure rises to equal atmospheric pressure, bubbles form at this point. This same phenomenon can also occur by reducing atmospheric pressure to equal liquid vapor pressure. In liquid process operations, when the liquid accelerates through the narrow area of the contraction section, the pressure can drop below the vapor pressure of the liquid, leading to the formation of bubbles. When the logistics continues to pass through the contraction section and the flow area expands, the flow velocity decreases and the pressure rises again, which leads to an increase in pressure recovery and makes the logistics pressure equal to the steam pressure.
When a bubble forms at the contraction section, it moves downstream until pressure is restored and causes the bubble to explode inwardly. These two steps - forming at the contraction section and subsequently exploding inwardly downstream - are called air pockets. Simply put, cavitation is a developmental stage characterized by the fact that the process of liquid vapor liquid is entirely carried out within a small area of the valve and in a subtle manner. Mild air hole injuries can be considered normal for certain conditions and can be addressed during routine maintenance. If ignored, severe air pockets will limit the estimated lifespan of the valve. It can also cause excessive leakage of the valve seat, alter the flow characteristics, and cause damage to the pressure vessel (valve body or pipeline, etc.).
Under certain severe pressure drop conditions, air pockets can damage valve components within minutes.
In short, there are five conditions required for the formation of air pockets: the fluid on both sides of the valve upstream and downstream must be liquid; 2、 When the fluid enters the valve or residual steam is generated by pressure drop downstream of the valve, the liquid must not have reached saturation state; 3、 The pressure drop of the contracted section must be reduced below the vapor pressure of the process fluid; 4、 The export pressure must be restored to the level of liquid vapor pressure; 5、 Liquids must contain certain entrained gases or impurities, which act as crystal nuclei in the formation of vapor bubbles. Crystal nuclei are sometimes called nucleons. Nucleons contained in process fluids resemble microscopic particles or dissolved gases. Because most process fluids contain particles or dissolved gases, there is a high possibility of forming vapor bubbles. In theory, if there are no nucleons in a liquid, some experts believe that air pockets will not form, but this is almost impossible, especially considering thermodynamic effects.
The generation and implosion of air pockets include five stages: when throttling through a valve, the flow rate increases while the liquid pressure decreases compared to the vapor pressure; 2、 Expanding into the vapor around a nuclear crystal nucleus, which can be a particle or carry gas; 3、 The bubble grows until the logistics movement moves away from the contraction section, and the pressure is restored to suppress the bubble growth; 4、 When the logistics movement moves away from the contraction section, the area expands and slows down the flow rate and increases the pressure. The increased pressure compresses or implodes bubbles, causing the vapor to return to the liquid; 5、 If the bubble approaches the surface of the valve, the force of the implosion directly points towards the surface of the valve wall, causing material fatigue.
The bubbles generated by the air pockets of FESTO solenoid valves are smaller and stronger than those generated by normal boiling. The energy released by the implosion bubbles can easily be heard as noise from valves or downstream pipelines, like stones rolling down pipelines. Normal noise is caused by excessive vibration, which can lead to metal or pipeline fatigue or calibration errors and malfunctions of sensitive instruments. In some cases, vibration can be reduced by firmly anchoring valves and pipelines to the ground or wall.
The long-term damage caused by FESTO solenoid valve cavitation is due to the deterioration of the material inside the valve body caused by the internal explosion of bubbles. When bubbles expand at the contraction section, they move downstream of the valve and then implode when pressure is restored. If bubbles are close to a metal surface, such as the valve body wall, they have a tendency to release implosion energy towards the valve wall. This phenomenon occurs when unequal pressure is applied to the bubble, because on the side of the cavity bubble adjacent to the object, the liquid pressure is lower, and the energy of the implosion is directed towards the surface (Figure 1). This principle is the same as that of deep load explosion in anti submarine warfare.
This valve is used in liquid systems. The machine equipment used to control the location, pressure, and flow rate of liquids is a machine equipment that enables the flow or stoppage of raw materials (liquids, vapors, powders) and their equipment and machinery in pipelines, and can manipulate the flow rate. Valves are important automatic control systems in liquid transportation systems.
Before operating the FESTO solenoid valve, please read the operating instructions carefully. In the operation process, it is necessary to eliminate the injection of steam and pay attention to checking the opening and closing signs of the valves. Check the appearance of the valve to see if it is wet and cold. If it is damp and cold, it must be treated with dryness and agitation. If other difficulties are found, they must be handled properly. Do not operate under common problems. If the electric control valve has been out of use for more than 3 months, check the clutch before starting. After confirming that the seesaw is in the manual position, check the cable sheath of the motor, the transformation and path of the electrical equipment.
FESTO solenoid valve is a widely used valve. Fully considering the tensile strength of the protruding surface and the necessary closing force, the rocker or remote rod is designed and manufactured based on general human resource management schemes. Therefore, it cannot be moved with a long pole or a long wrench. Some people are accustomed to using a wrench and should be careful. When opening the valve, the force should be stable to avoid excessive force to open and close the valve. It should be stable and not harmful. Some components of pressure valves with impact power switches have already fully considered that such impact forces cannot be the same as general valves.
backflow preventer
When the FESTO solenoid valve is opened, the joystick should be slightly flipped over to tighten the middle of the British thread to avoid loosening and damage. For the dark brown valve seat, remember to press the gate valve at the opening and closing positions to avoid collision between the bottom dead center and the liquid being opened. *Checking if everything is normal after turning it off is also very helpful. If the valve seat falls off or there are many stains in the sealing ring of the valve core, it is necessary to change the position of the gate valve when it is closed. Damaging the protruding part of the valve or the valve rocker.
Valve opening indication: When the pipe groove at the top of the gate valve wall of the globe valve, disc valve, and plug valve is parallel to the safety outlet, it indicates that the valve is in the fully open position; When the gate valve is rotated 90 degrees to the left or right. When the pipe groove and safety outlet are vertical, it indicates that the valve is in the closed position. Some globe valves, disc valves, and plug valves open based on the parallel surface of the wrench and safety outlet, and close when vertical. The operation process of three-way valves and four-way valves should be carried out based on the signs of opening, closing, and commutation. After the operation process, a movable operating handle should be selected.
The correct operation process of FESTO solenoid valve
The FESTO solenoid valve has undergone pressure testing before installation and is symmetrical. When the valve is in long-term operation, the operating personnel should pay attention to inspecting the valve. During the entire inspection process, everyone should avoid the import and export trade of the valve, inspect the seal of the valve, pull out the valve with a wrench, open it every once in a while, drain the stains, and inspect the coordination of the valve.
The correct operation process of FESTO solenoid valve
A steam trap is a valve that is easily clogged by waste such as water and waste. When opening, open the flushing valve and clean the pipeline. If there is an intake valve pipe, the bypass valve can be opened for temporary cleaning. For steam traps without cleaning pipes and inlet valve pipes, they can be removed, opened and cleaned, the shut-off valve closed, the steam trap installed, and then the shut-off valve opened to open the steam trap.
The correct operation process of FESTO solenoid valve
Before opening the pressure regulating valve, please open the bypass valve or flushing valve to clean the pipeline. After cleaning and clearing the pipeline, close the bypass valve and flushing valve, and then open the pressure regulating valve. Some steam pressure reducing valves contain steam traps, which must be opened. Then, slightly open the shut-off valve after the pressure regulating valve, and open the shut-off valve before the pressure regulating valve. Pay attention to the pressure gauge around the pressure regulating valve, adjust the adjusting screw of the pressure reducing valve to achieve the predetermined pressure after the valve, and slowly open the shut-off valve after the pressure regulating valve, and calibrate the pressure after the valve until it is satisfactory. Fix the adjustment screw and cover it with a maintenance cover.