1. The function of gate valve:
The opening and closing part of the gate valve is the gate plate. The movement direction of the gate plate is perpendicular to the direction of the fluid. The gate valve can only be fully opened and fully closed, and is not suitable for adjustment and throttling. The gate has two sealing surfaces. The two sealing surfaces of the most commonly used wedge gate valve form a wedge shape. The wedge angle varies with the valve parameters, usually 5o. The gate plate of the wedge gate valve can be made into a whole, called a rigid gate; it can also be made into a gate that can produce slight deformation to improve its craftsmanship and compensate for the deviation of the sealing surface angle during the processing. This kind of gate The plate is called an elastic gate. When the gate valve is closed, the sealing surface can be sealed only by the medium pressure, that is, the medium pressure is used to press the sealing surface of the gate plate to the valve seat on the other side to ensure the sealing surface sealing, which is self-sealing. Most gate valves adopt forced sealing, that is, when the valve is closed, external force must be relied on to force the gate plate to the valve seat to ensure the sealing performance of the sealing surface.
2. The function of the stop valve:
Quality comes from professionalism, and service lies in fulfillment. Manual stop valves and electric stop valves are easy to control, and the valve bodies are made of high-temperature and wear-resistant products such as cast steel, stainless steel, and ceramics. Taking advantage of the big stage of Shanghai, it attracted many elites in technology, sales and management. The company made a great leap forward and attracted some elites in technology, sales and management from other countries. As a result, the company gained popularity at home and abroad. With rapid development, some products have applied for patents, won the favor of municipal governments and users, and are exported to Southeast Asia and Europe.
A globe valve refers to a valve in which the closing member (valve disc) moves along the centerline of the valve seat. According to this movement form of the valve disc, the change of the valve seat opening is proportional to the valve disc stroke. Since the opening or closing stroke of the valve stem of this type of valve is relatively short, and it has a very reliable shut-off function, and because the change of the valve seat opening is proportional to the stroke of the valve disc, it is very suitable for regulating flow. Therefore, this type of valve is very suitable for use as a cut-off or regulating as well as throttling.
3. The function of butterfly valve
Compared with the above-mentioned valves, butterfly valves are lighter, larger in diameter, and cheaper. In the early 1980s, some gas companies once adopted butterfly valves. After about ten years of use, it is generally believed that the effect is not good. First, the sealing and isolation width of the butterfly valve is too narrow, which can easily cause the valve disc to overshoot or not be in place during closing, affecting the sealing; second, the valve disc is in the middle of the valve cavity, with large flow resistance and cannot pass through the cleaner; third, due to The central part of the seal is made of rubber or polytetrafluoroethylene, which is easily damaged or fallen off during gas erosion and has a short service life. Practice has proved that except for special locations, butterfly valves should not be used on gas pipelines. Some gas companies that have already used butterfly valves are (or considering) replacing other valves;
4. Function of flat gate valve:
The flat gate valve is a general valve that has only been used in gas pipelines in recent years. The flow resistance is small when the diameter is full. The seals on both sides are formed by PTFE or rubber O-rings pressed against the gate plate. This kind of valve is fully closed or When fully open, the middle cavity cannot be airless, which makes it difficult for users to quickly judge whether the valve is tightly closed during emergency repairs. If the middle cavity is airless, the opening and closing torque will increase rapidly; some manufacturers have reduced diameters, such as DN200 caliber. The inner diameter is only 150mm, so users should pay special attention. Therefore, this kind of flat gate valve is suitable for occasions with low pressure level and small nominal diameter.
5. Function of ball valve:
Ball valves are widely used because of their small flow resistance, small structural height, and good sealing performance. They have developed rapidly in recent years.