What Is a Stop Valve?
A stop valve (also known as a shutoff valve) is the type of valve that is designed to completely stop the flow of fluid or gas through a pipe. It is also known as an isolation valve or a shutoff valve. Stop valves are typically installed in plumbing, heating, and gas systems to control the flow of water, steam, or gas.
Stop valves work using a valve mechanism to stop fluid or gas flow through a pipe. The valve mechanism can be a gate, a ball, or a disk that is moved into position to block the flow. When the valve is closed, the fluid or gas stops flowing through the pipe. When the valve is open, the fluid or gas can flow freely.
Stop Valve (Globe Valve): Understanding the Nomenclature
A valve plays a crucial role in controlling the flow of fluids in a system, and one such valve, often found in both plumbing and industrial setups, goes by two different names: the Stop Valve and the Globe Valve. Let’s investigate the reasons behind these names and why they refer to the same valve.
The Unified Design and Purpose:
At its core, the design and purpose of both the stop and globe valves are identical. The valve consists of a movable disc or plug and a stationary ring seat, housed typically within a spherical body. The core function of this valve is to control or regulate fluid or gas flow. Its design allows for precise flow control, making it highly efficient for throttling applications.
The Nomenclature:
- Stop Valve: This name is a direct indication of its primary function. The valve can stop the flow when required. Simple, it tells users exactly what to expect from its operation.
- Globe Valve: The term’ globe’ in globe valve refers to its spherical shape enclosing the valve mechanism. The body of the valve, especially when viewed from the side, resembles a globe. This shape is integral to the valve’s functionality, as it allows for the efficient and controlled movement of the disc.
Why Two Names for One Valve?
The duality in naming often comes from historical, regional, or application-based preferences. It might have been introduced as a “stop valve,” emphasizing its functionality in specific regions or industries. In contrast, in others, the distinctive “globe” shape might have been the highlight leading to the name “globe valve.” Over time, as trade and information spread, both words came into popular usage. However, regardless of the name, the mechanics and application remain consistent.
Whether you come across a schematic, product list, or an industry veteran referring to a stop valve or a globe valve, they’re discussing the same piece of equipment. Recognizing this dual terminology can aid in more transparent communication and understanding in professional settings.
What Is a Gate Valve?
A gate valve is a kind of valve that controls the flow of fluid through a pipe by using a gate or wedge-shaped disc that moves up and down to block or allow the flow of fluid. Gate valves are commonly used in industrial applications such as oil and gas and water treatment.
The gate valve is designed to have a straight-through flow path, which means that when the valve is fully open, the fluid can flow through the valve with very little resistance or pressure drop. This makes gate valves an excellent choice for applications where low flow resistance and high flow capacity are essential.
The gate valve is operated by turning a handwheel or a gearbox that rotates a threaded stem. The stem is connected to the gate or disc, which moves up and down in a straight line to control fluid flow. When the valve is fully open, the gate or disc is entirely out of the flow path, allowing the fluid to flow freely. When closed, the gate or disc is lowered into the flow path, blocking fluid flow.
Stop Valve Vs. Gate Valve: What is the Difference
Structure Difference
Stop valves typically have a globe-shaped body, with the valve seat and disc arranged perpendicular to the flow path. The valve stem is attached to the disc, which is moved up and down by turning a handwheel or actuator to control fluid flow. The seat of the valve is built to provide a tight seal when the valve is closed, which prevents any fluid from flowing through.
In contrast, gate valves have a straight-through flow path and a wedge-shaped gate or disc that moves perpendicular to the flow direction to control fluid flow. The gate or disc is attached to the valve stem, which is rotated to raise or lower the gate to control the flow. When the valve is fully open, the gate or disc is completely out of the flow path, allowing fluid to flow freely with minimal resistance. When the valve is fully closed, the gate or disc is lowered into the flow path, creating a tight seal that stops the fluid flow.
Both valves are available in various materials, such as brass, bronze, cast iron, and stainless steel, to suit different applications and environments. They may also feature additional components such as packing materials to prevent leakage, bonnets to protect the valve stem, and handwheels or actuators for manual or automated operation.
Stop Valve Vs. Gate Valve: Working
Stop valves work by using a valve mechanism, such as a disc or a ball, that is moved into position to block fluid flow. The valve mechanism is typically perpendicular to the flow path, with the valve stem attached. When the valve stem is turned, the valve mechanism moves up or down to block or allow fluid flow. When the valve is fully open, the mechanism is entirely out of the flow passage, allowing the fluid to flow freely. When the valve is fully closed, the mechanism is lowered into the flow path, blocking the fluid flow.
On the other hand, gate valves use a wedge-shaped gate or disc that is moved perpendicular to the flow path to control the fluid flow. The gate or disc is attached to the valve stem, which is rotated to raise or lower the gate to control the flow. When the valve is fully open, the gate or disc is completely out of the flow path, allowing fluid to flow freely with minimal resistance. When the valve is fully closed, the gate or disc is lowered into the flow path, creating a tight seal that stops the fluid flow.
Stop valves are typically used in applications where the flow needs to be completely shut off. In contrast, gate valves are commonly used in applications where a straight-through flow path is desired, and the valve is either fully open or closed.
Sealing Surface
The sealing surface of the gate valve has a degree of self-sealing capability, and its valve core is in close contact with the sealing surface of the valve seat, resulting in a leak-proof seal. The stop valve’s sealing surface must be forcefully closed to accomplish sealing.
Stop Valve Vs. Gate Valve: Flow Control Difference.
The main difference in flow control between stop valves and gate valves is that stop valves can regulate flow or completely shut off the flow, while gate valves can only be fully open or fully closed.
Stop valves use a disc, ball, or plug as the valve mechanism, which can be moved up or down to regulate or shut off flow. By adjusting the valve mechanism’s position, the fluid flow can be controlled to a certain extent.
On the other hand, gate valves use a wedge-shaped gate or disc as the valve mechanism, which can only be fully raised or lowered to allow or block fluid flow. This means that gate valves cannot be used to regulate flow but are instead used for applications where only full flow or no flow is required.
Stop Valve Vs. Gate Valve: Lifespan
The longevity of the stop valve is determined by the quality of the material used in its manufacturing. Most home stop valves have a life expectancy of 10 to 15 years. As a result, if you are purchasing a home that is 10 or 15 years old, maintenance may be required during the operation of the stop valve. However, if it leaks constantly, it must be replaced. Regular maintenance must be avoided in the replacement. On the other side, gate valves last up to 25 years with proper maintenance.
Stop Valve Vs. Gate Valve: Material
Both stop and gate valves are available in various materials to suit different applications and environments. Here is a chart comparing the materials commonly used for stop valves and gate valves:
| Material | Stop Valve | Gate Valve |
| Brass | ✔️ | ✔️ |
| Bronze | ✔️ | ✔️ |
| Cast iron | ✔️ | ✔️ |
| Carbon steel | ✔️ | ✔️ |
| Stainless steel | ✔️ | ✔️ |
| Alloy steel | ✔️ | ✔️ |
| PVC | ✔️ | |
| CPVC | ✔️ | |
| Polypropylene | ✔️ | |
| PTFE | ✔️ |
Stop Valve Vs. Gate Valve: Types.
Stop and gate valves are available in various types, each designed for specific applications and environments.
Some common types of stop valves include:
- Ball valves: These valves have a ball-shaped valve mechanism that rotates to control fluid flow.
- Check valves allow fluid to flow in only one direction, preventing backflow.
Some common types of gate valves include:
- Parallel slide gate valves: These valves have two parallel gates that slide up and down to control fluid flow.
- Wedge gate valves:
These valves have a wedge-shaped gate that moves perpendicular to the flow path to control fluid flow.
- Knife gate valves:
These valves have a sharp, knife-like gate that cuts through the fluid to control the flow.
Sluice gate valves: These valves are commonly used in water and wastewater treatment applications and have a flat gate that slides up and down to control fluid flow.
Stop Valve Vs. Gate Valve: Comparison
Here’s a comparison chart of stop valves and gate valves:
| Feature | Stop Valve | Gate Valve |
| Flow Path | T-shaped | Straight-through |
| Valve Mechanism | Disc, ball, or plug | Wedge-shaped gate or disc |
| Operation | Turn the valve stem to move the valve mechanism | Rotate the valve stem to raise or lower the gate |
| Flow Control | Regulate flow or completely shut off the flow | Fully open or fully closed |
| Pressure Drop | Moderate | Low |
| Leakage | Can experience some leakage | Tight shutoff |
| Applications | Suitable for many applications, including regulating flow and shutting off the flow | Suitable for applications requiring a straight-through flow path and minimal pressure drop, such as in the oil and gas industry |
| Types | Globe valves, ball valves, check valves, diaphragm valves | Parallel slide gate valves, wedge gate valves, knife gate valves, sluice gate valves |
Stop Valve Vs. Ball Valve: Sizes
Gate valve size
| 1/2″ | 3/4″ | 1″ | 1-1/4″ | 1-1/2″ | 2″ | 2 ½” | 3″ and 4″ |
Stop valve size
| Size | DN |
| ½ inch | 15 |
| ¾ inch | 20 |
| 1 inch | 25 |
| 1 ¼ inch | 32 |
| 2 inch | 50 |
Globe (Stop) Valve vs. Gate Valve: Differences in Applications and Installations
Globe (stop) valves and gate valves serve similar purposes: regulating the flow of fluids in piping systems. However, they are distinct in their design, functionality, and typical use cases. Understanding these differences can be critical for choosing the right valve for your application.
Globe (Stop) Valve Applications:
- Flow Control: Globe valves are excellent for regulating flow. They can be partially opened or closed to modulate the fluid passing through.
- Industry Use: Often used in chemical and petrochemical plants, food processing industries, and systems where flow control is essential.
- Residential Use: Under the name of “stop valve,” they are commonly found in domestic settings to shut off water for repairs or emergencies.
Gate Valve Applications:
- Full Open or Close: Gate valves are not suitable for throttling but are excellent for applications where fluid flow should either be fully stopped or allowed to flow freely.
- Water Supply: Commonly used in water treatment plants and irrigation systems.
- Oil & Gas: Frequently used in the oil and gas industry, high-pressure resistance and a tight seal are crucial.
Installation:
Globe (Stop) Valve:
- Orientation: Can be installed in horizontal or vertical orientations.
- Accessibility: For residential applications, often installed in easily accessible locations.
- Flow Direction: These valves are directionally marked, and incorrect installation can compromise their efficiency.
Gate Valve:
- Orientation: Generally installed horizontally but can be vertical if the system demands.
- Weight Support: Given that they can be quite heavy, especially for large pipelines, additional support may be needed.
- Clear Path: These require a full open path for the gate to rise or descend, which means they need vertical space in the installation design.
While both globe (stop) and gate valves have unique advantages and disadvantages, the key takeaway is to match the valve type with its intended application and installation needs. Globe valves are more versatile in flow control but may require more frequent maintenance. Gate valves, on the other hand, are best for systems that require only full flow or complete shutoff, offering less resistance to fluid flow but not suitable for throttling.
Final Words:
It’s crucial to give equal weight to the advantages and disadvantages of both a gate valve and a stop valve before settling on your next engineering or plumbing project. In high-pressure situations, gate valves are preferable to stop valves due to their increased durability; nonetheless, they require special equipment to be used effectively. On the other hand, stop valves can be utilized quickly and easily without any particular tools, but their weaker structure means they shouldn’t be used in high-pressure situations. Only you can decide which is best for you, but learning more about the two valves will give you additional options.