The globe valve is one of the most widely used valves in life. However, to reduce cost, butterfly valves can also be used in some places to replace globe valves. Although the butterfly valve is not used for adjustment, it has simple structure, seldom waste of materials and light weight. This also makes the price of butterfly valves low. This article will tell you about these two valves and compare them.
The Globe Valve
The globe valve is a forced sealing valve. The closing member (disc) of globe valves moves along the centerline of the valve seat. The opening and closing parts of the globe valves are plug-shaped discs, the sealing surface is flat or conical, and the disc moves linearly along the center line of the valve seat.
The Butterfly Valve
Butterfly valve uses circular butterfly plate as the opening and closing part and rotates with the valve stem to open, close and regulate the fluid channel. The butterfly plate is installed in the diameter direction of the pipeline. In the cylindrical channel of the butterfly valve body, the disc-shaped butterfly plate rotates around the axis. The rotation angle is 0 ° ~ 90 °. When it rotates to 90 °, the valve is fully open.
The butterfly valve is applicable to the pipelines conveying various fluid media in the engineering systems of generator, gas, natural gas, liquefied petroleum gas, city gas, cold and hot air and so on.
1.The Working Principle
The globe valve closes when the sealing surface of the valve disc and the globe valve seat closely fit with the pressure of the valve rod to prevent the medium from flowing. A valve that uses a disc to open, close, or regulate the medium flow by reciprocating about 90 °. With good flow regulation function and closing sealing characteristics, the butterfly valve is not only simple in structure, small in volume, light in weight, low in material consumption, small in installation size and driving torque, simple and rapid in operation.
The globe valve has better regulating performance than the butterfly valve, while the butterfly valve perform not well. This is generally used in the occasion where only the switch is required.
The price of globe valves are higher than that of butterfly valves.
The globe valve is simple in structure, easy to manufacture and maintain, which also has good regulating performance. It is widely used in the transmission pipeline of various media. However, there is a change of direction when the fluid passes through the globe valve, so the resistance is large. Therefore, it is not suitable for the pipeline with high viscosity, containing suspended substances and easily crystallized materials, nor for the vent valve and the valve of low vacuum system. Globe valves are widely used in various pressure fluid pipelines, steam and compressed air pipelines. They are commonly used block valves, which are mainly used to connect or cut off the medium in the pipeline and regulate the flow. The globe valve is applicable to a wide range of pressure and temperature, but it is generally used for medium and small diameter pipes.
Butterfly valves, also known as flap valves, are simple control valves. Since the butterfly valve could not be closely matched with the pipe wall, it is only suitable for regulating the flow but cannot be used to cut off the pipeline. It is often used to regulate the flow on the pipeline conveying air and flue gas. Butterfly valves use the circular butterfly plate rotating with the stem as the opening and closing part. The butterfly valve is mainly used to cut and off. At the present, butterfly valves are used in low-pressure and large-diameter pipelines more frequently.
The valve stem of the globe valve has a relatively short opening or closing stroke with a reliable cut-off function. Because the change of the valve seat opening is proportional to the stroke of the valve disc, it is very suitable for regulating the flow.
The reason why the stop valve is popular is that the sealing surface friction is small when opening and closing, which is relatively durable. The opening height is not high, the manufacturing is easy, and the maintenance is convenient. It can also be made into a large caliber. Both valves can work well, but attention should be paid to the functions and characteristics of each valve when selecting.
We have more information about valves, it includes the globe valve size chart.
The plug valve is an angular stroke rotary motion manual valve with a cylindrical or conical rotary plug inside. It allows or prevents fluid straight-through flow through the valve body by rotating the rotary plug. A plug valve provides a straight passage through the port so fluid can flow through the open plug with minimal turbulence. It has one or more horizontal channels to allow flow through the valve when open. Plug valves are often used to move liquids or gases but rarely solids. Flow can be either fully open or fully closed in either direction. In addition, plug valves are simple and generally economical.
The typical plug valve consists of a body, bonnet, stem, and plug.
The plug is the opening and closing part of the plug valve, which is cylindrical or conical. Cylindrical cocks have a rectangular or circular channel section, and conical cocks have a rectangular, trapezoidal or circular channel section. These shapes make the structure compact and lightweight, but cause a certain pressure drop.
The stem of the valve connects the disc with the actuator. It helps the movement of the actuator to the plug disc so as to open or close the plug disc. The plug valve has a small stem that connects to the disc.
(3)The Plug Valve Body
The body connects to the pipes through an end connection.
The globe valve is a forced sealing valve. It refers to a valve where the closing member (disc) moves along the centerline of the valve seat. The opening and closing parts of the globe valve are plug-shaped discs. It’s sealing surface is flat or conical, and the disc moves linearly along the center line of the valve seat.
The typical globe valve composes of a body, bonnet, stem, disc, seat and basket.
The globe valve body is the main pressure-bearing structure of the valve,which is easy to identify because it constitutes the mass of the valve. It contains all the internal parts of the valve that touches with the substances that the valve controls. The valve cover is connected to the valve body and contains the fluid, gas or slurry.
Seat rings provide a stable, uniform and replaceable closing surface. The valve seat is usually screwed in or screwed in. This pushes the cage down against the lip of the seat and secures it securely to the body.
The stem of globe valve links the actuator with the inside of the valve and transmits the driving force. The stem of the actuator control valve is smooth and the stem of the manual valve is threaded.
The bonnet is ready for a leak-proof closure to the valve body. The threaded portion of the stem goes through a hole in the bonnet with matching threads. Globe valves may have a screw-in, union or bolted bonnet.
1.The sealing performance of the plug valve is better than that of the globe valve.
2.Globe valves are better than plug valves for flow through.
3.The globe valve has a long stroke and slow opening speed. The plug valve is used for frequent operation, and it opens and closes quickly and easily.
4.Due to the change in the flow direction of the medium through the valve, the small flow resistance of the globe valve is high. The fluid resistance of the plug valve is small.
5.The plug valve is simple in design and low in cost.
Plug valves are often used on low-temperature, low-flow pipelines because their spool seals are sensitive to high temperatures. The use of globe valves is extremely common, but due to the large opening and closing torque and the long structure length, the nominal diameter is usually limited to less than 250mm, and some are up to 400mm, but special attention should be paid to the direction of inlet and outlet when selecting. Generally, most of the globe valve medium below 150mm flows in from the bottom of the valve disc, and most of the globe valve medium above 200mm flows in from the top of the valve disc. This is due to the closing torque of the valve. In order to reduce the opening or closing torque, generally more than 200mm globe valves are equipped with internal bypass or external bypass valve.
Globe valves, a type of control valve, are used to stop, start and regulate the flow of media through a pipe. From the outside, they have a spherical body design. And inside, a plug-like disc sits on the end of a threaded rotating stem to raises and lowers to control media flow. Globe valves are part of the linear motion valve family, which means that the valve mechanism moves along a straight line.
How Does a Globe Valve Work?
Named for their spherical body shape, globe valves bodies are separated into two halves by an internal baffle. The seat on the globe valve disc can be screwed in to close the valve. Most automated glove valves use smoother stems not threaded ones. And use an actuator assembly to open and close.
Gate valves are linear motion valves that are used only to start or stop media flowing through a pipe. They are shutoff valves instead of control valves, since they are not ideal for throttling.
Generally, they are designed with a flat or wedge-shaped disc on the end of a threaded stem, which is turned via a wheel and raises and lowers to operate the valve. Gate valves provide a tight shutoff, and are commonly used for isolating media. Because they do not force media to change course (as in a globe valve) , gate valves cause little pressure drop.
Gate and globe valves often work in tandem inside a piping system. Gate valves can be designed with rising or non-rising stems, which is helpful for space optimization.
How Does a Gate Valve Work?
When a gate valve is activated, the stem will turn clockwise or counter clockwise to raise or lower the disc inside the pipe. In its closed position, the disc lodges between the seats in the base of the valve, providing a full stop at a right angle to the media flow. The disc can be shaped like a wedge, knife or parallel panel.
Unlike gate or globe valves, ball valves are a type of quarter-turn valve that utilizes a bead shaped ball with a hole in the middle to control the flow of media. Called a bore or port, the hole in the middle of the ball allows media to pass through the valve body when opened, and is rotated 90 degrees to stop flow. The port is aligned perpendicular to the valve body in the closed position.
How Does a Ball Valve Work?
Ball valves are a type of quarter-turn valve which use a hollow, perforated and pivoting ball to control the flow. It opens when the hole of the ball is in line with the flow and closes once pivoted 90-degrees by the valves handle. The handle lies flat in alignment with the flow whilst open and perpendicular once closed. This allows for easy visual confirmation of the ball valves status.
Can regulate media flow.
Can handle high-pressure, high-temperature, corrosive or viscous media
Create a high-pressure drop
Introduce resistance to media flow
Economical option for on/off control
Offer little resistance to media flow
Not ideal for regulating media flow
The sustained flow of media in a partially open position
Can cause water hammer
Prone to leaks: less durable than ball valves
Long lasting and durable
Versatile media compatibility
Provide fast cycle speeds
Good for high-pressure, high-volume applications
Offer little resistance to media flow
Not ideal for regulating flow
Fast cycle time can lead to water hammer
As a producer of high-quality valves, ZJCLV can meet various customized requirements of customers. We can produce ball valves from 1/2 inch ball valves to larger ones.
The globe valve can regulate flow or pressure as well as complete shutoff of flow. It is sometime as a pressure relief valve or a check valve.
The s-shaped configuration creates a large amount of resistance within the valve. The design of the globe valve body forces the flow to change direction within the valve itself. This change in direction creates substantial pressure drop and turbulence. The globe valve is therefore not recommended when flow resistance and pressure drop are to be avoided.
In most installations, the commodity is routed into the valve’s body from below the valve seat and disc. This flow direction uses the pressure of the commodity to aid in the opening operation of the valve. It also reduces wear on the valve seats and disc.
The globe valve can shut off the fluid. In the case of completing closing or opening, the fluid can be cut off, or the full channel can be circulated. When the globe valve is opened and the opening height of the valve disc is 25% – 30% of the nominal diameter, the flow reaches the maximum, indicating that the valve has reached the full open position. The globe valve is a rising stem type, and the hand wheel rotates and rises with the stem.
The Working Principle
Suppose a water cylinder with a cover, water enters from the bottom of the cylinder and flows out from the cylinder port. And the cylinder head is equivalent to the closing part of the valve. If you lift up the cylinder head by hand, it is as the working principle of the globe valve.
Advantages and Disadvantages
1.The structure is simple, and the manufacturing and maintenance are convenient.
2.The working stroke is small and the opening and closing time is short.
3.Good sealing, small friction between sealing surfaces and long service life.
4.The structural forms of globe valve body include straight through type, direct current type and right angle type. Straight through type is the most common structure, but its fluid resistance is the largest. Direct flow fluid has low resistance and is mostly used for fluids with solid particles or high viscosity.
The article is from ChuangLian Valve Co., Ltd. For more information, please find our website: www.clvvalve.com