Figure 1: Globe valve (left) and gate valve (right)
Despite their similarities at first inspection, globe and gate valves have significant differences that make each suitable for their applications. When choosing between these two valves for an application, understanding the application's pressure, sealing, and flow requirements can ensure the correct valve is selected. This article discusses the differences between globe and gate valves to allow an educated decision before choosing between the two valves.
Globe valves and gate valves are multi-turn, linear motion valves, meaning both valves require multiple turns to open or close. The closing mechanism moves up and down in a straight line to turn open or close the valve. At this point, similarities between the valves begin to diminish.
The globe valve differs from most valves because its name derives from its body shape (rounded) rather than its disc, which is the gate valve's convention. Its disc moves up and down to allow or block the flow, similar to a gate.
Read more on globe valves and gate valves to get a comprehensive understanding of both.
As seen in Figure 2, a gate valve is a straight-through, bi-directional valve, meaning its design permits flow directly through it in both directions. The only change to the flow occurs when the gate valve is closed, and the flow stops.
Figure 2: A gate valve flow properties when it is closed (left) and open (right).
A globe valve, on the other hand, has more turns for the flow path. As seen in Figure 3, the flow can take a z-shaped path (T- or Z-valve), an oblique path (Y-valve), or a 90° turn path (angle valve).
Because a globe valve diverts flow in a specific way, it has an inlet and an outlet port. Typically, an arrow on the outside of the valve's body will indicate the valve's flow direction. Also, the flow diversion causes a significant pressure drop through the globe valve. In contrast, a gate valve's pressure drop is nearly non-existent.
Figure 3: Globe valves' flow paths: T- or Z-valve (left), angle valve (center), and Y-valve (right)
Both gate valves and globe valves can operate as on/off valves. A gate valve is not meant to bused to throttle flow, but a globe valve can. Flow diverts within the globe valve and becomes parallel to the valve seat. This design makes globe valves efficient flow throttlers. Globe valves become unsuitable for throttling flow at larger diameters (above DN 150). Gate and globe valves can be operated mechanically, pneumatically, or electrically.
Note: With other factors equal, Y-valves are the least efficient at throttling flow because the valve seat is not parallel to the flow direction. However, this also means that Y-valves have the smallest pressure drop.
At a quick glance, gate valves and globe valves are not easy to tell apart. The following traits are what to look for to tell the difference:
Globe and gate valves may have similar or different materials for their housing and seals. Read our chemical resistance guide to learn more about the advantages and disadvantages of the various materials. See the following chart to learn about more advantages and disadvantages.
Globe valve Gate valve Application Used for flow regulation (e.g., cooling water systems and fuel oil systems) More suitable for slurry due to less space in the valve's body for sediment to get stuck and build up Flow control Can be used or on/off control and can throttle flow Can be used for on/off control and cannot regulate the flow Flow capacity Lower Higher Flow direction Unidirectional Bi-directional Flow restriction/pressure drop Flow diversion within the valve's body creates significant pressure drop Full-bore valve, meaning there is no reduction to flow and pressure drop is insignificant Power requirement Needs a large amount of force or an actuator to close under high pressure Needs less power to close under high pressure Operating conditions Can operate at higher temperatures Can operate at higher pressures Cost More expensive than a gate valve due to its complicated structure Cheaper Leakage More effective sealing because force is applied to the disc when closed Good sealing properties Installation space Takes up less vertical space, but requires more horizontal space If a rising-stem style, needs more vertical space, but less horizontal space Weight Heavier Lighter Ports Can have a 3-port configuration for straight-through flow Two portsTable 1: Globe valve and gate valve advantages and disadvantages chart
Gate valves and globe valves are both excellent shut-off valves. However, when choosing between them, neither valve will outperform the other in every single application. Consider the following factors:
The above variables are typically the most important when selecting a shut-off valve. Refer to Table 1 for further information.
Globe valves
Gate valves
Globe valves have better sealing than gate valves and last longer. However, gate valves have significantly lower pressure drop.
One significant advantage of gate valves over globe valves is that they require significantly less power to close since they close perpendicular to flow rather than parallel as globe valves do.
For more information difference between gate valve and globe valve, please get in touch with us!