Advantages and disadvantages of globe, plug, safety, check valves
Posted: 05/11/2020 12:43:55 Hits: 93
1. Globe valve:
A globe valve refers to a valve in which the closing member (valve flap) moves along the center line of the valve seat. According to the movement of the valve flap, the change of the valve seat port is directly proportional to the stroke of the valve flap. Because the opening or closing stroke of the valve stem of this type of valve is relatively short, and has a very reliable cut-off function, and because the change of the valve seat port is proportional to the stroke of the valve flap, it is very suitable for adjusting the flow rate. Therefore, this type of valve is very suitable for shut-off or adjustment and throttling.
① During the opening and closing process, the friction force between the disc and the sealing surface of the valve body is smaller than that of a gate valve, so it is wear-resistant.
② The opening height is generally only 1/4 of the valve seat channel, so it is much smaller than a gate valve;
③ Usually, there is only one sealing surface on the valve body and valve disc, so the manufacturing process is relatively good and it is easy to maintain;
④ Because the filler is generally a mixture of asbestos and graphite, the temperature resistance level is higher. Generally, steam valves use globe valves.
① Since the flow direction of the medium through the valve has changed, the minimum flow resistance of the globe valve is also higher than that of most other types of valves;
② Due to the longer stroke, the opening speed is slower than that of the ball valve.
2. Plug valve:
A plug valve refers to a rotary valve with a plunger-shaped closing member. Through the 90 ° rotation, the channel port on the valve plug is connected or separated with the channel port on the valve body to realize opening or closing. The shape of the valve plug can be cylindrical or conical. The principle of a plug valve is basically similar to that of a ball valve. The ball valve is developed on the basis of a plug valve, which is mainly used for oilfield exploitation, and used in petrochemical industry.
3. Safety valve:
A safety valve refers to the overpressure protection device on the pressure vessel, equipment or pipeline. When the pressure in the equipment, container or pipeline rises above the allowable value, the valve automatically opens, and then discharges in full to prevent the pressure in the equipment, container or pipeline from continuing to rise; when the pressure decreases to the specified value, the valve would be automatically closed in time to protect the safe operation of equipment, containers or pipelines.
4. Steam trap:
In the transportation of steam, compressed air and other media, some condensate will form. In order to ensure the working efficiency and safe operation of the device, these useless and harmful media should be discharged in time to ensure the use of the device. It has the following functions: ① can quickly remove the condensate produced; ② prevent steam leakage; ③ remove air and other non-condensable gases.
5. Pressure reducing valve:
A pressure reducing valve is a valve that reduces the inlet pressure to a certain required outlet pressure through regulation and depends on the energy of the medium itself to keep the outlet pressure stable.
6. Check valve:
A check valve is also known as reflux valve, cut-off valve, non-return valve, back pressure valve and one-way valve. These valves are automatically opened and closed by the force generated by the flow of the medium in the pipeline, which belongs to automatic valves. Check valves are used in pipeline systems. Their main functions are to prevent backflow of the medium, to prevent the pump and drive motor from reversing, and to prevent the medium in the container from releasing. Check valves can also be used on the pipelines that provide supplementary to auxiliary systems where the pressure may rise above the system pressure. Check valves can be mainly divided into swing type (rotating according to the center of gravity) and lifting type (moving along the axis).