Author:Site Editor Publish Time: 2018-10-07 Origin:Site
The structure of piston(lift) check valve is similar to globe valve,but these two kinds of having some differences between globe valve and piston check valve,the operation of piston check valve is flow automatic,the globe valve have a handwheel to operating,this is most difference of valve's type.
The opening and closing part of the globe valve is a plug-shaped valve flap having a flat or tapered surface, and the valve flap moves linearly along the center line of the valve seat. The movement of the valve stem is a lifting rotary lever type that can be used to control the flow of various types of fluids such as air, water, steam, various corrosive media, mud, oil, liquid metal and radioactive media. Therefore, this type of globe valve is well suited for globe or regulation and throttling. Due to the relatively short opening or closing stroke of the valve stem of this type valve, and the very reliable cutting function, and because the change of the valve seat opening is proportional to the stroke of the valve flap, it is very suitable for the adjustment of the flow rate.
The sealing pair of the globe valve is composed of a valve sealing surface and a valve seat sealing surface, and the valve stem drives the valve flap to move vertically along the center line of the valve seat. During the opening and closing process of the globe valve, the opening height is small, the flow rate is easy to adjust, and the manufacturing and maintenance are convenient, and the pressure is applicable to a wide range.
The globe valves are divided into three categories: straight-through globe valves, right-angle globe valves, and oblique globe valves.The most obvious advantage is that during the opening and closing process, the friction between the valve flap and the sealing surface of the valve body is smaller than that of the gate valve, so it is wear-resistant. The opening height is generally only 1/4 of the diameter of the seat channel and therefore much smaller than the gate valve. Usually there is only one sealing surface on the valve body and the valve flap, so the manufacturing process is better and easy to repair.
Piston(Lift) check valve: The check valve that slides along the vertical center line of the valve body. The internal thread check valve can only be installed on the horizontal pipe. On the high pressure small diameter check valve, the valve can adopt the ball. The butterfly check valve has the same valve body shape as the globe valve, so its fluid resistance coefficient is large. Its structure is similar to the globe valve, the valve body and the valve flap are the same as the globe valve. The upper part of the valve flap and the lower part of the valve cover are machined with a guide sleeve, and the valve guide can be easily lifted and lowered in the valve guide. When the medium is downstream, the valve flap is opened by the medium thrust.
When the medium stops flowing, the valve flap is self-retained. The drooping falls on the valve seat to prevent the medium from flowing back. The direction of the inlet and outlet passages of the straight-through butterfly check valve is perpendicular to the direction of the valve seat passage; the vertical lift check valve has the same direction of the medium inlet and outlet passages as the valve seat passage, and its flow resistance is smaller than that of the straight-through type.