The piston valve is composed of the valve body, plunger, sealing ring and other parts. Piston valves are divided into plunger gate valves and plunger globe valves. The plunger valve changes the structure of the axial seal of the globe valve in the past, and adopts radial sealing, so that the radial component generated on the sealing ring is greater than the pressure of the fluid, so as to ensure good sealing performance. At the same time, the past metal-to-metal seal is changed, and the seal composed of stainless steel plunger and flexible non-metallic material is adopted, which not only improves the sealing performance. It also does not require packing, and maintenance is very simple, if there is a leak, just close the valve first and tighten the nut of the bonnet symmetrically and properly.
When the plunger is plugged into the inner hole of the sealing ring, the sealing ring around the plunger is pressed firmly by the load applied back to the valve cover by the bonnet nut, so as to ensure the seal, when the valve opens and draws out the plunger, the material of the sealing ring returns to the original state under the action of elasticity. The sealing pair of the plunger valve with hard seal structure is composed of a precision ground and polished plunger and a hard seat surface after surfacing welding. After rough machining, the plunger is subjected to chemical treatment such as carburizing, high-frequency quenching and nitriding, and the hardness can be as high as HRC58 64.
Compared with the globe valve, the piston valve has a long life and saves effort in operation, but the adjustment stroke is longer than the globe valve, so the throttle control is more difficult than the globe valve, and the plunger valve is not suitable for places with clear requirements for adjustment. As a result, a piston valve is a very effective type of valve with a number of advantages. First of all, it has excellent sealing properties and can effectively prevent fluid leakage. Secondly, due to its soft sealing structure, the sealing ring can be automatically adjusted with the movement of the plunger, so it has good adaptability and reliability. In addition, the piston valve has a long service life and low labor operation, and can be suitable for high flow rate and high differential pressure working environment. However, piston valves have a longer adjustment stroke than globe valves, so piston valves are not suitable for locations where precise flow regulation is required.
In practical applications, piston valves are widely used in various industrial fields, such as petroleum, chemical, pharmaceutical, etc. In these fields, piston valves can effectively control the flow of various fluids (such as gases, liquids, etc.) to ensure safety and stability in the production process. At the same time, due to its excellent sealing performance and long life, the plunger valve has also been widely used and recognized.
In conclusion, the piston valve is a very good type of valve with many advantages and practical application value. With the continuous development of industrial technology, the application prospect of piston valves will also be broader.