A globe valve, is a type of valve which belongs to the family of linear valves, they can be manual, using a hand wheel to adjust the linear stroke of the stem, or actuated via pneumatic, electric, or hydraulic means, depending on the application, actuated valves may have a positioner equipped to enable feedback to the controller.
How does a globe valve work?
A globe valve works by raising or lowering the valve plug, which is connected to the stem off, or onto the seat to enable flow of media, or shut off the flow of media, by placing the plug onto the seat, sealing the flow through the valve.
A globe valve is not bi-directional and must be fitted in the direction of flow indicated on the body marking, this is normally by an arrow, depending on the application of a globe valve, it can be flow over, or flow under the plug.
What are the parts of a globe valve?
The globe valve can be broken down into several parts:
- The body, this can be made from various material, carbon, stainless, and other exotic materials.
- The stem, is used to connect to the control device, whether manual handwheel, or actuated
- The bonnet, this houses the packing and sealing material to prevent leakage via the stem, the bonnet can come in a few different types; standard, extended, cryogenic and bellow, all depending on the media, conditions, and specifications required
- Plug, this will determine the flow based on the trim, which can be Equal percentage, Linear or Quick Open, depending on application
What are globe valves used for?
Globe valves are used for the controlled flow of media, to the next process in the line, each valve will have a specific CV value to allow the correct amount of media to pass.
What are the different types of a globe valve?
- Single Seated
- Double Seated
- Split Body
- “Y“ Pattern
- Cage Guided
- Double, Top, Stem Guiding
What is the difference between a gate valve and a globe valve?
The main difference between a Gate and Globe valve is the mechanism used to allow flow of media, the Gate valve, as the name suggests has a flat paddle (gate shape) which will retract into the bonnet when fully open, whereas the Globe valve uses the plug to control the flow of media, and can be shaped like a bath plug for better means of description, these do vary in shape depending on the application and CV required.
Why do globe valves have a higher pressure drop than gate valves?
The globe valve controls the flow of media through the valve, where a gate valve is normally for open or closed application
Globe valve shut off is accomplished by moving the plug against the flow of media rather than across it as in the case with a gate valve. The direction of flow through a globe valve involves changes in direction, resulting in greater resistance to flow, causing high pressure drops across the valve
What are the advantages of a globe valve?
A Globe valve offers the following advantages:
- Tight shutoff, Leakage of less than 0.01% of max Cv (class IV)
- High pressure drop capability, full rated classes
- Low pressure recovery, High flow capacity
Is a globe valve full port?
A globe valve is not classified as a full port valve, as the stem and plug are involved in the path of flow.
How do you install a globe valve?
Globe valves must be installed in the direction of flow according to the indication marker on the valve, it is not recommended to install the valve upside down, as this can cause dirt or impurities to fall onto the bonnet packing.
Can globe valve be used for throttling?
Globe valves are excellent for flow control (throttling), and went used with a positioner and actuator will enable feedback to the control program to allow the correct percentage of flow for the given set value.
How can Flexachem help you?
Flexachem have over 38 years plus experience in globe and gate valves.
Flexachem can provide actuation for all of our valves, including actuated check valves, our main pneumatic actuator is Norbro, with a variety of switch boxes and feed back control, which is application specific to each installation.
We offer and support leading brands – Gestra globe valves.
If you would like to find out more about our globe & gate valve range, why not contact contact one of our valve specialist team?
Brendan Merrigan (External) – mob: 087 2598124
Vicki McGrath – tel: 021 461 7207
Brian Barry – tel: 021 461 7211
Tim Quigley – tel: 021 461 7209
Conor Foley – tel: 021 461 7206
Ross O’Donovan – tel: 021 461 7230
Tel: 021 461 7200