What are the advantages and disadvantages of oxygen shut-off valves?

What are the advantages and disadvantages of oxygen shut-off valves? The types of oxygen shut-off valves are divided into external thread type and internal thread type according to the position of the valve stem thread. According to the flow direction of the medium, there are straight-through type, direct-current type and angle type. The globe valve is divided into sealing form, including packing seal globe valve and bellows seal globe valve.
The structure of the oxygen globe valve body includes straight-through, straight-through and right-angle types. The straight-through type is the most common structure, but its fluid resistance is the largest. The direct-flow fluid resistance is small, and it is mostly used for fluids containing solid particles or high viscosity. The right-angle valve body is mostly forged, which is suitable for the globe valve with smaller passage and higher pressure.
The oxygen shut-off valve is a forced-sealing valve, so when the valve is closed, pressure must be applied to the valve disc to force the sealing surface not to leak. When the medium enters valve six from below the valve disc, the resistance that the operating force needs to overcome is the friction force between the valve stem and the packing and the thrust generated by the pressure of the medium. The force to close the valve is greater than the force to open the valve, so the valve The diameter of the stem should be large, otherwise the failure of the top of the valve stem will occur.
After the appearance of the self-sealing valve, the medium flow direction of the oxygen shut-off valve is changed from the top of the valve disc into the valve cavity. At this time, under the action of the medium pressure, the force to close the valve is small, but the force to open the valve is large, and the diameter of the valve stem can be reduce accordingly. At the same time, under the action of the medium, this form of valve is also tighter. my country's valve "Three Chemicals" once stipulated that the flow direction of the globe valve should be from top to bottom. When the oxygen shut-off valve is opened, when the opening height of the valve disc is 25% to 30% of the nominal diameter, the flow rate has reached the maximum, indicating that the valve has reached the fully open position. Therefore, the fully open position of the globe valve should be determined by the stroke of the valve disc.
First, the advantages of oxygen shut-off valve:
(1) Good sealing performance, small friction between sealing surfaces, and long service life.
(2) The structure is simple, and the manufacture and maintenance are more convenient.
(3) The working stroke is small and the opening and closing time is short.
2. Disadvantages of oxygen shut-off valve:
(1) The adjustment performance is poor.
(2) The fluid resistance is large, and the force required for opening and closing is large.
(3) It is not suitable for media with particles, high viscosity and easy coking.