Performance comparison of gate valves with different structures
Publisher：Botou Valve
Gate valves can be divided into wedge type, single gate type, elastic gate type, double gate type and parallel gate type according to their internal structure. According to the difference of stem support, it can be divided into open stem gate valve and dark stem gate valve. The main performance advantages of the gate valve are: the valve fluid resistance is small, because the gate valve body is straight-through, medium flow does not change direction, so the flow resistance is smaller than other valves.
Sealing performance is better than globe valve, opening and closing is also more labor-saving than globe valve. It can be used not only in steam and oil, but also in medium with granular solids and high viscosity. It can also be used as vent valve and valve in low vacuum system. Gate valve is a valve with double flow direction, which is not limited by the flow direction of medium, so it is suitable for pipelines where medium may change the flow direction, and it is also easy to install.
The main performance shortcomings of gate valves are: high design dimension, long start-up and shut-down time. When opening, it is necessary to lift the disc to the upper part of the valve chamber, and when closing, it is necessary to drop all the discs into the seat, so the disc has a long opening and closing journey. Because of the friction between the two sealing surfaces of the valve plate and the valve seat in the opening and closing process, the sealing surface is easy to scratch, which has an impact on the sealing performance and service life, and is not easy to maintain.
Performance comparison of several gate valves with different structures: wedge single gate valve, simple structure than elastic gate valve, sealing performance at higher temperature is not as good as elastic gate valve or double gate valve. It is suitable for high temperature medium which is easy to coke. Elastic gate valve is a special form of wedge type single gate valve. Compared with wedge gate valve, it has good sealing performance at high temperature, and the gate is not easy to be stuck after being heated. It is suitable for steam, high temperature oil products and oil and gas media, and for frequent switching parts.
It is not suitable for medium which is easy to coke. Double gate valves have better sealing performance than wedge gate valves. When the inclination angle of sealing surface and seat fit are not very accurate, they still have better sealing performance. After the sealing surface of the gate is worn out, the metal pad at the bottom of the top of the spherical surface can be replaced and used. Generally, there is no need to surfacing and grinding the sealing surface. This is an advantage that the single gate and the elastic gate do not have.
It is suitable for steam, high temperature oil products and oil and gas media, and for frequent switching parts. It is not suitable for medium which is easy to coke. Parallel gate valves, sealing performance is worse than other types of gate valves. It is suitable for medium with lower temperature and pressure. The processing and maintenance of the sealing surface of the gate and seat are simpler than other types of gate valves.
