Globe valves and gate valves are used for different applications. This article discusses about the topic globe valve vs gate valve in detail.
Globe valves are used for regulating the flow whereas the gate valve is used to completely shut off the flow. Lets see more differences in detail in further sections of this article.
A globe valve is a type of control valve that is used for regulating or controlling the flow in a pipeline.
It is different from a ball valve. It consists of movable plug and a stationary ring seat fitted generally inside a spherical body.
Image: Globe valveImage credits: Wikipedia
A ball valve is also a type of control valve that is used to regulate or control the flow in pipeline.
It is different from a globe valve. It has a hollow or perforated ball which is used for controlling the flow of fluid in the pipeline.
Globe valve finds its applications in more areas than a gate valve does as it can be used for regulating flow and pressure as well.
Globe valves are most commonly used in plant piping. They can be used as a pressure relief valve or a check valve and they are also suitable for manual and automatic operations.
A gate valve may be cheaper but it has many disadvantages over ball valve. So application wise, ball valve is superior than a gate valve. Although in high pressure applications, gate valve is desired more. Lets see why.
A globe valve consists of a stem, bonnet and plug. The relative positions of these can determine whether the globe valve is open or not.
If the stem is completely inside bonnet, then the plug will rest on body where a hole is given for the water to flow. This means the globe valve is closed. If the stem rises from the bonnet then it is in open condition.
To open or close, one has to rotate the handle as done with screws.
First we need to understand what is isolation valve, it is simply a valve that can stop the fluid flow process to given location.
A typical globe valve can be used for lowering the pressure as well as isolation purposes. But globe valves show higher pressure drop than straight through valves (I.e ball valve, gate valve etc). So, a globe valve can be used for isolation when pressure drop is not a controlling factor of the flow.
Absolutely yes. Every mechanical component has a life expectancy and so does a gate valve. Following are the cases where it can fail-
Normally gate valves are used when the liquids need to be shut off rather than being regulated.
Gate valves can be used in following scenarios-
Yes, a gate valve can reduce pressure if a bypass controller is attached to it.
The gate valves with larger diameters are fitted with a bypass controller. This way the pressure is reduced by a significant value before even reaching the valve itself. Pressure is reduced because in high pressure, the friction becomes a significant problem.
There is no visual indicator that indicates whether the gate valve is open or closed. However, the position of knob can be used to determine whether the valve is open or closed.
A gate valve consists of a knob which when rotated counter clockwise, opens the valve and closes when turned clockwise. As it opens the valve, knob rises up indicating that the valve is open and closed when the knob is resting on the bonnet.
A globe valve can be called as a control valve.
Globe valve can be used to regulate or completely stop the flow making it a control flow valve.
Yes, a globe valve is unidirectional. Unidirectional means that it allows flow in only one direction, it cannot change the direction of the flow completely.
When compared to other valves, only gate valve is bi directional whereas globe and check valves are uni directional.
A gate valve can be jammed if not used over several years. It has to be tested after certain period of time else it will be damaged and we would not even know.
To open up a jammed valve, we can simply try moving the knob back and forth slowly with a plier. This way the jamming will open up gradually. Remember not to do it very fast else it might get damaged.
It is very easy to adjust a gate valve or rebuild it again after dismantiling it. First we check the position till where the knob goes inside.
If the knob goes completely inside then the valve need not be fixed. If it goes upto only a certain length, then we will have to flush it out. Flushing means getting rid of excessive or unwanted materials lying inside the valve. This can be done by loosening one of the screws in the body.
Each and every mechanical component has its own advantages and disadvantages.
The advantages of gate valves are-
The disadvantages of gate valves are-
Number of turns required for closing or opening a gate valve can be found out using the AWWA formula.
Number of turns is equal to three times the nominal valve size plus two or three turns of the operating nut.
For example 5 x 3= 15 plus 2 or 3= 17 or 18 turns.
The function of globe valve and gate valve are given in the table as shown below-Globe valveGate valveRegulates, starts and stops the flow of fluid.Used for completely shutting off flow of fluids rather than regulating.Can be used as ON/OFF valve.Used in heating circuits and sewer piping.Can be used for throttling purposes.They are used with large pipe diameters because they are easy to construct.Table: Functions of globe valve and gate valve
The term globe doesnt necessarily mean that the valve will have a round shape. In addition to that, it comes in various types. They are-
The differences between a globe valve and butterfly valve are given below-Globe valveButterfly valveThe disc of the globe moves in a straight line.Butterfly valve has a plate shaped disc that rotates around its own axis.Main parts are bonnet, stem, body and handwheel.Main parts are valve body, stem, butterfly plate and sealing ring.Can be used for cutting off or regulating the flow of fluid.It is used for flow regulation mostly for throttling purposes.Table: Difference between globe valve vs butterfly valve
These valves work by inserting a gate (mostly rectangular) or wedge between the path of flow. This plate is actuated by threaded stem which itself is actuated by hand or electric motor.
A directional valve is designed to work only in three functions.
The three functions in which the directional valves work are- stop the fluid flow, start the fluid flow or change the direction of fluid flow.
Lubrication is necessary else the ball inside the ball valve will jam and the valve will be rendered useless.
We can lubricate the ball valve by spraying penetrating lubricant around the ball valve handle precisely between the coloured handle and the pipe portion of the ball valve. After applying lubricant, turn the knob back and forth so that the lubricant can pass through the tight crack and enter the body of the valve.
This way the lubricant can penetrate inside and lubricate internal components of the valve too.