Globe valves are handwheel operated and can moderate water flow. But, as a trade-off, they also cause higher pressure loss.
Choosing the appropriate valve for the appropriate job is paramount, as different variants offer different services and features. Currently, most of these kinds of products are originally manufactured by China globe valve manufacturer because of the cost consideration.
What is a globe valve, and how does it work?
To decide if a globe valve is right for you, consider its three main features. Firstly, they are the LATERAL MOVEMENT VALVES, which if you don’t already know, means that they open or close, depending on the up and down motion of a stem. Secondly, they can allow or stop fluid flow, or sometimes even throttle fluid flow.
Some valves, such as gate valves, only possess an open or closed status, however, globe valves can throttle flow without fully stopping it. Lastly, they can cause significant head losses, as a comparison to the other valves.
How globe valves work?
On the exterior, globe valves have three components: a handwheel, a bonnet, and a body. The bonnet houses a stem when the valve is attached to the main valve, and when the handwheel is turned clockwise, it opens the valve and vice versa. The stem screws up and down in the bonnet based on which direction you turned the handwheel. On the end of the stem is the small, yet no less important part called a plug, or a disk, which is classified into metallic and non-metallic.
The valve also has another part that plays a small role when the valve is in action. The seat is a metal frame that segments the body in two chambers and has a hole, which is designed for fluid to pass through. When the valve is open, fluid flows up through the opening of the seat. To shut it up, the stem is screwed down until the disk blocks the seat’s opening, thus losing the valve, and disallowing the fluids to flow through.
One of the primary advantages of globe valves is their mastery to throttle or regulating flow. Apart from being only just closed or open, they can be half-closed or half-open (What do you see?). This allows to change the status and flow velocity of the fluids.
However, despite looking like a great valve, there are slight disadvantages to this valve. The biggest disappointment about globe valves is that they have higher pressure loss rates, and there are many head losses they create. Head loss, better known as pressure loss, is referring to the amount of resistance a fluid finds as it moves through the pipeline. The more backflow, the more pressure gets lost. Gravity and friction and turbulence can all cause pressure loss. Turbulence is usually the main factor in creating pressure loss.
Globe valves force fluids to change their direction as it passes through the seat, creating head loss and turbulence. The exact amount of heat loss is always swayed, and there are many influences to this unit. However, it is still possible to preview the pressure losses from the many variants of different valves using a metric system dubbed the L/D Coefficient.