Valve bellowsIt is a valve that uses the lift of the valve stem to drive the valve head to change the distance between the valve disc and the valve seat to realize the opening and closing control. Bellows valve is widely used in chemical production. Valve is mainly used in the actual production of water, steam, compressed air and other pipeline control, but not suitable for high viscosity, easy to crystallize materials.

The structure of the valve bellows is more complex, but the actual operation is simple and labor-saving. It has good regulation flow and cut-off channel performance. The switching speed is very slow, and water hammer rarely occurs. The cut-off valve has a compact structure and obvious appearance. The top of the valve is equipped with a handwheel and stem, and the middle is equipped with threads and stuffing box seals.

During the use of the valve bellows, the main way to judge the opening and closing status of the valve is to observe the height of the valve stem from the valve cover to control the operation of the valve. There may be a gap between the connecting part of the valve stem and the valve cover, which is easy to cause medium leakage. This can be solved by package sealing. The valve stem thread of the small globe valve is arranged in the valve body, so it has a long contact time with the medium in use and is easily corroded by the medium.

Therefore, in order to prevent the short service life of the valve, the manufacturer of the valve bellows believes that the installation of the valve should refer to the direction of the fluid, and pay attention to keep the inlet and outlet of the pipe low, that is, from the bottom to the top through the valve seat port. The purpose of this installation is to reduce the fluid resistance in the valve body, thereby reducing the opening and closing force of the valve. At the same time, when the valve is closed, it can prevent the valve stem and stuffing box from contacting the medium, thereby reducing damage and leakage.

The opening and closing part of the valve bellows is a cylindrical valve disc, the sealing surface is flat or conical, and the valve disc moves linearly along the center line of the fluid. The movement of the valve stem includes the lifting rod type (the valve stem is raised and lowered, the handwheel is not raised) and the valve rotating rod type (the handwheel and the valve stem rotate and rise together to fix the nut on the valve body). The valve bellows is only suitable for full opening and full closing, and allows adjustment and throttling when customized.

When the shut-off valve is opened, when the opening height of the valve disc is 25% to 30% of the nominal diameter, the flow rate has reached the value, indicating that the valve has reached the fully open position. Therefore, the fully open position of the valve bellows should be determined according to the stroke of the valve disc. Bellows safety valve: Bellows can eliminate the impact of back pressure fluctuations on valve performance, and can also protect springs and other internal components from medium corrosion. Can effectively prevent the medium leakage. Bellows globe valve: The bellows and the packing of the valve form a double seal to prevent medium leakage, which is mainly used for toxic media. Bellows drain valve: Bellows are made of heat-sensitive elements, which are used to control the drainage and gas blockage of the valve.