(Zhejiang Yongyong County Technical Yidu Bureau Zhejiang 325100) (Zhejiang Yongyi Valve Factory) analyzes the spring full-open liquefied gas safety valve sealing structure before improvement. For example, the valve seat sealing surface is a knife-shaped metal sealing surface, and the valve sealing surface It consists of a wide PTFE sealing ring. This type of sealing structure has the following problems: it is prone to leakage, and the sealing property does not meet the requirements of the standard. Under the action of the spring force, the valve flap is pressed against the valve seat against the medium force to form a seal. After the valve disc and the valve seat sealing surface are in close contact, the knife-shaped valve seat sealing surface is pressed into the planar valve-valve sealing surface. 'After a period of time, the valve sealing surface will leave a certain indentation. During the opening, returning and returning of the safety valve, the valve flap may rotate, and the radial relative position of the valve flap and the valve seat may change. Since the center of the valve sealing surface has a coaxiality with the guiding outer circle of l2 mm, the matching clearance between the valve flap and the guiding sleeve is.
170~0.292mm, the integrated offset center amount is about 0.23mm, and the knife-shaped sealing surface is only 3 wide. Therefore, the radial position of the valve sealing surface cannot be returned to the previous sealing position after the safety valve is discharged, and the medium will never be The indentation that is pressed by the knife-shaped sealing surface leaks, and the sealing property is difficult to meet the requirements of GB12243-89 spring direct-loading safety valve.
Short service life. After the safety valve is opened several times, the radial relative position of the valve disc and the valve seat is constantly changing, the indentation of the valve sealing surface is gradually increased, the contact area between the valve flap and the valve seat is gradually increased, and the sealing specific pressure is reduced. The leakage increases continuously, which affects the sealing performance 5~08, 90.) The processing is difficult, and the geometric size and angle are difficult to meet the requirements. Moreover, the grinding method cannot be adopted, and the roughness is preferably only if the processing precision of the sealing surface of the valve seat and the roughness are not met, the sealing performance is directly affected.
Improvements have been made to the problems existing in the safety valve sealing structure. After many design and trial production, the original sealing structure has been improved. The improved sealing structure is, for example, a flat seal type. The sealing surface of the valve seat (hereinafter referred to as the hard sealing surface) is a flat sealing surface of 3.5 to 4 mm wide. The valve sealing surface (hereinafter referred to as the soft sealing surface) is composed of a PTFE sealing ring with a valve flap. The head of the soft sealing surface is 2 mm wide, and the root width b will change with the change of the working pressure level. See Table 1; the outer surface of the soft seal is 2.5mm high and the inner height is 2mm. The characteristics of the improved flat seal structure are as shown in Table 1: The height difference between the inner and outer surfaces of the soft seal is 0. 5mm, the width difference between the head and the root is in the medium force. Under the action, the soft sealing surface expands slightly outward or there is a tendency to expand outward. Therefore, under the action of the spring force, the valve flap overcomes the medium force, and the inner ring of the soft sealing surface is in close contact with the hard sealing surface. Tests have shown that the sealing performance is good, the opening sound is crisp, and the opening performance is good.
Flat sealing structure, wide hard sealing surface and narrow soft sealing surface (upper page 20) Table 1 Working pressure grading MPa valve æ sealing surface root width b, mm Note: valve sealing surface axial outer surface head and root Connection: When b<2mm, connect with smooth arc; Table 1 is divided into Xs. The group of the first group of the root of the tank is severely leaked (not caught). (The chief commander is that the company manager is not in the gas storage. , dispatched by the dispatching staff on duty, after the arrival of the chief commander, the dispatching room attendant assists the chief commander to dispatch the accident report company and the rescue personnel, broadcast the call for help, command the station personnel to eliminate the nearby fire source, set the warning zone, and organize Accident rescue. The guard rang the alarm and reported 119 to open the fire door; it is strictly forbidden to enter any warning zone for the fire and the vehicle. The hydrocarbon pump room attendant starts the small pump of the fire pump and the spare fire pump. The station personnel execute the dispatching instructions and enter the scene to handle the accident. After the manager arrived at the station, as the company's chief commander, dispatched various functional departments to rescue. The deputy manager cooperates with the general commander to organize and liaise with various functional departments. The chief engineer acts as the chief commander of the accident scene and directs the rescue personnel to carry out on-site rescue. The stationmaster cooperated with the chief engineer to organize personnel in the station to rescue the danger. The deputy stationmaster cooperates with the hydrocarbon pump attendant to ensure that the fire pump is running. The electrician ensures that the generator room and power distribution room are operating normally. The team is responsible for transferring the vehicle outside the guard zone. The office cooperates with the doorman for on-site security, personnel management and vehicle grooming. The engineering department entered the scene of the accident and listened to the command of the chief engineer. The porter is responsible for transferring the countertop heavy bottles when necessary. The filling worker entered the scene of the accident and listened to the command of the stationmaster. The user department and the business department cooperate with the protection alert zone.
The water injection system is inside the tank. If the storage capacity of all storage tanks is at a higher liquid level, the liquid phase in the accident tank should be evenly distributed; or the liquid phase in other storage tanks should be poured out by the tank truck, and the liquefied petroleum gas in the accident storage tank should be replaced to the tank. In the process, create conditions for repairing and sealing; C. Flange clamp, high pressure strong injection seal or plugging with pneumatic plugging bag; d. After successful plugging, the tank will be liquefied gas and water drain Empty, repair and replace the damaged parts.
After the accident emergency plan is formulated, on the one hand, the accident emergency plan must be distributed to the relevant personnel (including cadres, employees, etc.), organize them to study, unify their thinking, raise awareness, and enable them to master certain accident emergency handling knowledge; The aspect must regularly organize emergency response drills to improve the emergency response capability and coordination capabilities of employees. At the same time, through the drills, it is possible to check whether the emergency plan for the accident is realistic and feasible; if there is any problem, it can be corrected in time. This will make the accident emergency plan have a meaning of buying.
The sealing surface wears little and the soft sealing surface is evenly polished. The more the opening times, the smoother the soft sealing surface and the better the sealing performance.
After the hard sealing surface is finished, the grinding can be used to meet the roughness requirement. The soft sealing surface is turned into a valve disc after the PTFE sealing ring is inserted into the valve flap to achieve the roughness and geometric size requirements, and the sealing surface is convenient to process without increasing the manufacturing cost.
The flat sealing structure is suitable for a spring full-open liquefied gas safety valve with a nominal pressure of PN16 MPa and 2.
Conclusion The liquefied gas safety valve products with improved sealing structure all meet the requirements of GB12243-89. Since the product was mass-produced and put into use in 1993, there have been no quality problems.
There is a lot of room for it. During the process of opening, discharging and returning the safety valve, the radial relative position of the valve flap and the valve seat will not affect the contact between the hard and soft seals (1999-05-28). Hard seal surface roughness is good (up to /), to soft
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