Analysis of advantages and disadvantages of valve and Globe Valve
Gate valve The gate valve controls the valve opening by the up and down movement of the valve plate. The valve plate is like a gate. When the gate valve is closed, the sealing surface can be sealed only by the medium pressure, that is, the sealing surface of the gate valve can be pressed to the valve seat on the other side only by the medium pressure to ensure the sealing of the sealing surface, which is self sealing. Most gate valves are forced sealed, that is, when the valve is closed, the gate shall be forced to the valve seat by external force to ensure the tightness of the sealing surface. The types of gate valves can be divided into wedge gate valve and parallel gate valve according to the configuration of sealing surface. Wedge gate valve can be divided into single gate plate, double gate plate and elastic gate valve; Parallel gate valves can be divided into single gate plate and double gate plate. According to the thread position of the valve stem, it can be divided into rising stem gate valve and Non rising stem gate valve. There are many domestic manufacturers of gate valves, and most of the connection sizes are not unified.
Advantages of gate valve 1. Low flow resistance. The medium channel inside the valve body is straight, the medium flows in a straight line and the flow resistance is small.
2. It is labor-saving when opening and closing. Compared with the Globe Valve, the movement direction of the ram is perpendicular to the medium flow direction whether it is open or closed.
3. High height and long opening and closing time. The opening and closing stroke of the ram is large, and the lowering is carried out through the screw.
4. Water hammer is not easy to occur. The reason is that the shutdown time is long.
5. The medium can flow in any direction on both sides, which is easy to install. Both sides of the gate valve channel are symmetrical.
6. The structural length (the distance between the two connecting end faces of the shell) is small.
7. The utility model has the advantages of simple shape, short structural length, good manufacturability and wide application range.
8. Compact structure, good valve rigidity, smooth channel, small flow resistance, stainless steel and cemented carbide sealing surface, long service life, PTFE packing, reliable sealing, light and flexible operation
The disadvantages of gate valve are that the sealing surfaces are easy to cause erosion and scratch, and it is difficult to maintain. The overall dimension is large, which requires a certain space for opening and closing, and the opening and closing time is long. The structure is complex.
Globe valve The Globe Valve moves up and down by the circular valve core to control the valve opening. Globe Valve, also known as Globe Valve, is one of the most widely used valves. It belongs to forced sealing valve. Therefore, 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 the valve from below the valve disc, the resistance to be overcome by the operating force is the friction between the valve stem and 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 diameter of the valve stem should be larger, otherwise the failure of valve stem jacking will occur.
Advantages of Globe Valve 1. Double sealing design (bellows + packing) if the bellows fails, the valve stem packing will also be avoided;
2. Leakage and meet international sealing standards;
3. No fluid loss, reduce energy loss and improve plant equipment safety;
4. The structure of Globe Valve is simpler than that of gate valve, and the manufacturing and maintenance are more convenient.
5. The rugged bellows seal design ensures zero leakage of the valve stem and provides maintenance free conditions.
6. The bellows seal Globe Valve adopts the design of bellows seal, which completely eliminates the shortcomings of rapid aging and easy leakage of ordinary valve stem packing. It not only improves the use of energy efficiency, increases the safety of production equipment, reduces the maintenance cost and frequent maintenance, but also provides a clean and safe working environment.
7. The sealing surface is not easy to wear and scratch, with good sealing performance. There is no relative sliding between the valve disc and the sealing surface of the valve body during opening and closing, so the wear and scratch are not serious, with good sealing performance and long service life.
Disadvantages of Globe Valve 1. Large fluid resistance and power consumption.
2. It is not suitable for media with particles, high viscosity and easy coking.
3. Poor regulation performance.
4. When fully opened, the valve disc is often eroded.
5. The opening and closing torque is large, the opening and closing is laborious, and the opening and closing time is long.