Globe valves are closing-down valves with a linear motion closure member that moves squarely on and off the seat. Regardless of its shape, the closing member is usually referred to as a disc.
The disc travel is proportional to the seat opening—this proportionate link between valve opening and disc motion works in a flow rate change. Globe valves are best for throttling and controlling fluid flow in small pipe systems.
The design of a globe valve needs two changes in the flow direction. This results in resistance in liquid lines and an unfavorable pressure reduction. The flow is directed up through the seat ring and against the bottom disc when the globe valve is installed. This keeps dirt and debris from accumulating above the disc.
Globe valves are suitable for various tasks in fluid handling process piping systems. But, a globe valve works as a block or isolation valve. Its primary function is to control flow in half an open state. Because maintaining a tight seal against the strong force pressing up on the disc is challenging. Design selection is essential when considering globe valves for on-off isolation service. The globe valve has a shorter stem movement between open and closed positions and is easier to repair.
Principles of globe valve working:
The actual work of a globe valve is to stop, start, and regulate flow. A usually spherical body consists of a moveable disc and a stationary ring seat. A globe valve’s seat is in the middle of and parallels the pipe, and the disc closes the opening in the seat.
The valve stem lowers or raises a disc when the handle twists, either manually or with an actuator. The fluid flow is turned off after the disc is completely lowered. The fluid flow is at its highest when the disc is completely lifted. When the disc rises to a lower level, the fluid flow regulates the disc’s vertical journey.
Types of globe valve:
There are three significant types of globe valves.
- Angle type
y-type globe valve:
They-type valve rectifies the high-pressure loss problem related to the Z-shape valve. The Y valve’s stem and seat form a 45-degree angle. It provides a straight flow path with minimal flow resistance when completely expanded. It can stay open for a long time without sustaining significant erosion.
This valve is typically used for throttling during startup or seasonal operation. Garbage is usually removed from drain lines using Y-valves. It’s employed in services with a high head and those with pressure drop problems.
Z-type globe valve:
These globe valves have the most straightforward design. As a result, these valves are often used in the manufacturing business. The Z-type separation has a seat in the spherical body. The valve disc and stem move vertically to the pipe axis. The valve seat is seated, resulting in high-pressure drops. There are two sorts of valves: T type and Z type valves.
The seat is accessible from the hood. This bonnet is connected to the valve body by a large opening on the top. The stem acts as a gate valve through the bonnet. These globe valves have an enormous pressure loss and flow rate.
In closed throttling systems, Z-type valves are very helpful. These globe valves are ideal for applications that need throttling and do not require pressure loss.
Angle globe valve:
This globe valve is an upgraded version of the Z-type globe valve. These valves may change the flow direction by 90 degrees without extra pipe bends or welds. In the opposite direction of the flow, the disc opens. These water valves handle the slugging effects. They’re also suitable for use with varying flow rates. It has a somewhat lower flow coefficient than Y shut-off valves.
Applications of globe valve:
- Cooling water systems that need flow regulation
- A fuel oil system with a regulated flow focused on leak-tightness.
- When leak-tightness and safety are top priorities, use high-point vents and low-point drains.
- Feedwater, chemical feed, air extraction from the condenser, and extraction drain system
- Turbine seals and drains
- Turbine lube oil system and others
A ball valve is a device that rotates a ball-shaped disc to control the flow of various substances. It’s open when the hole in the ball stands up with the flow entering. The valve closes when the handle is rotated 90 degrees, stopping the flow. When the valve is open, the handle becomes parallel to the flow. Here When it’s close, it’s still perpendicular to it.
This allows for easy visual validation of the valve’s condition. In closed settings, the 1/4 turn has two functions. It is possible in two ways clockwise or counterclockwise. These valves have a long lifespan. To turn it on or off, a slight motion is required. They have a lengthy lifespan.
How ball valve work:
Multiple ports, or apertures in the valve, are possible with ball valves. Two-way ball valves are often used for classic on/off control and have two ports. Multi-port valves are used in applications that need more than one media source.
A ball valve’s port can be manually or automatically opened or closed to control media flow. You’ll need handles or levers and an operator to control the valve manually. The valve can be maintained without an operator using electric using pneumatic actuation. Actuation is appropriate for complex control systems or those located in difficult-to-reach locations.
Applications of ball valve:
Ball valves are used in every aspect of our life. Following are some of the prominent applications.
- Washing machine
- Outdoor hoses
- Vehicle wash system
- Biopharma industry
- Oil and gas
- Food and beverages
Globe valve versus ball valve :
The primary distinction between a globe and a ball valve is opening and closing the flow. A globe valve controls and throttles the flow, but a ball valve does not control the flow and only closes it. It can regulate the flow with a globe valve. Ball valves are well-suited to shutting the flow without causing any pressure drops.
Another distinction is that a ball valve has a rotating stem and ball horizontally. In contrast, a globe valve has a vertically moving stem and plug. The ball valve keeps the flow closed for an extended period. In high-pressure systems like fire hoses, a ball valve is more efficient.
If flow regulation is the concern, it’s advisable to use a globe valve. Globe valves are significant in cooling systems and other applications. Ball valves, unlike globe valves, have no installation limits. Furthermore, when compared to globe valves, ball valves are lighter.
Ball valves are also more durable and perform well after many cycles. They are more reliable even after a lengthy period of misuse. Ball valves have a modest obstruction of their fluid and are thus quieter. Still, globe valves have a significant fluid obstruction and may become noisy after many years of operation.