In piping systems, globe and gate valves are two common types of valves. There are some differences between them in terms of structure, flow direction, sealing surface, opening and closing parts, and flow direction. This article will introduce the differences and advantages and disadvantages of globe valves and gate valves in detail to help you better understand the differences and application scenarios of these two types of valves.
First, the structure is different.
The structure of the globe valve is relatively simple, the size is small, the weight is light, the material consumption is less, and the installation and maintenance are more convenient. However, the tightness of the globe valve is poor, and if its working principle is to rely on the stem pressure to press the disc, its tightness is not very ideal.
The structure of the gate valve is more complex than the globe valve, the volume is larger, it has greater resistance to the water flow, and there are many types of gate valves, which can be divided into two kinds according to the length of the valve stem: open rod type and dark rod type. The handwheel is not exposed, and the bracket must be opened and closed as usual, which is not light enough.
Second, the flow direction is different.
The globe valve can only flow in one direction in the pipeline, so it is also called a one-way valve. The flow resistance of the globe valve is not large, and it is labor-saving to open and close without support. However, the shut-off type control valve consisting of a shut-off valve may oscillate when flow regulation is used.
Gate valves can flow in both directions in the pipeline, so they are also called two-way valves. The flow resistance of the gate valve is not large, and it is labor-saving to open and close without support. However, the gate type control valve composed of a gate valve may oscillate when the flow rate is regulated.
Third, the sealing surface is different.
The sealing surface of the globe valve is the general name of the static (line) seal of the disc and the valve seat and the dynamic (line) seal of the stuffing box (sleeve). The shape, material and processing quality of the sealing surface directly affect the sealing performance and service life of the globe valve.
The sealing surface of the gate valve generally adopts a metal-to-metal sealing structure. In some cases, non-metal-to-metal and metal-to-metal sealing structures can also be used. The sealing pair of the gate valve (gate plate and valve seat) is in the periodic opening and closing process in the closed state, due to periodic friction and impact, the metal-to-metal sealing method is easy to cause the abrasion of the sealing surface and the surface fatigue failure, resulting in the decline of sealing performance.
Fourth, the opening and closing parts are different.
The opening and closing parts of the globe valve are plug-shaped disc and disc-shaped valve seats, and their main function is to cut off or connect the medium flow. In the fully open position, the weight of the medium tends to fall, which automatically prevents the vivid compression of the closing and ensures re-opening.
The opening and closing parts of the gate valve are the gate (the general name of the opening and closing parts), and the direction of movement of the gate is perpendicular to the direction of the fluid, and can only be fully opened and closed. It cannot be adjusted and throttled. The ram has two sealing surfaces that can act at the same time (machining) or separately (processing and forming). If the processing material for the two sealing surfaces is the same (the same material is processed at the same time), a good sealing effect can be obtained.
Fifth, the flow direction is different.
The structure of the globe valve determines that it is clockwise to close the valve (in order to facilitate the user's operation, the pneumatic actuator is driven by a clockwise rotation direction, and the valve is rotated 90 degrees to close the valve). Its flow direction is that the pressure of the medium decreases the higher (left) it goes. Its flow direction is perpendicular to the direction in which the medium changes.
The structure of the gate valve determines that the higher the pressure of the medium is (right) the greater (i.e., the greater the pressure to the right). Its flow direction is that the pressure of the medium decreases the further down (left) (i.e., the further to the left, the less pressure). Its flow direction is parallel to the change direction of the medium.
Hopefully, through the introduction of this article, you have a deeper understanding of the difference between globe valves and gate valves. In practical applications, the appropriate valve type can be selected according to different needs and occasions to achieve better use results. If you have any further questions or need further assistance, please do not hesitate to contact us.