gate valve working principle – ZECO Valve

Working Principle and Function of Gate Valve

Jerry — Mon, 27 Jun 2022 13:00:06 +0000

Gate valves are cut-off valves and are usually installed on pipes with a diameter greater than 100mm to cut off or connect the flow of medium in the pipe. Because the disc is a gate type, it is commonly called a gate valve.

Advantages of Gate Valve

The gate valve has the advantages of low switching effort and low flow resistance. But the sealing surface is easy to wear and leak, the opening stroke is large, and the maintenance is difficult. The gate valve cannot be used as a regulating valve and must be in the fully open or fully closed position.

Working principle of Gate Valve

The working principle is: when the gate valve is closed, the valve stem moves downwards, relying on the sealing surface of the gate valve and the seat of the valve to be highly smooth, flat, and consistent. They can prevent the medium from flowing through, and rely on the top wedge to increase the sealing effect. The closing part moves along the vertical direction of the center line.

Types of Gate Valve

There are many types of gate valves, which can be divided into wedge types and parallel types according to their types. Each type is divided into a single gate and a double gate.

The valve body of the gate valve adopts a self-sealing form. The connection between the bonnet and the valve body is to use the upward pressure of the medium in the valve to force the sealing packing to be compressed to achieve the purpose of sealing. The gate valve packing is sealed with high-pressure asbestos packing with copper wire.

The gate valve structure is mainly composed of the valve body, the valve cover, the frame, the valve stem, the left and right discs, and the packing seal device.

Body Material of Gate Valve

The valve body material is divided into two types: carbon steel and alloy steel according to the pressure and temperature of the pipeline medium. Generally installed in the valve of a superheated steam system, t>450℃, the valve body is made of alloy material, such as a boiler exhaust valve. For valves installed in water supply systems or pipelines with medium temperature t≤450℃, the valve body material can be carbon steel.

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Difference Between Ball Valve and Gate Valve – Ball Valve vs Gate Valve

Jerry — Wed, 22 Jun 2022 06:03:41 +0000

1. Ball Valve Working Principle and Gate Valve Working Principle

Ball valve: the opening and closing parts (ball) is driven by the valve rod and rotate around the axis of the ball valve. The ball valve is mainly used to cut off, distribute and change the flow direction of the medium in the pipeline. It can be closed tightly with only 90-degree rotation and a small rotation torque. The ball valve is most suitable to be used as a switch and shut-off valve, a v-ball valve.

Gate valve: the gate is the gate, the movement direction of the gate is perpendicular to the direction of the fluid, the gate valve can only be fully open and fully closed, and cannot be adjusted and throttled. The gate valve is sealed by contact between the valve seat and the gate. Usually, the sealing surface will be overlaid with metal materials to increase wear resistance, such as overlaying, stainless steel, etc. The ram has a rigid ram and elastic ram. According to the different rams, the gate valve is divided into a rigid gate valve and an elastic gate valve.

2. Characteristics of Ball Valve vs Gate Valve

Ball valve: wear-resistant; good sealing performance; because the seal of hard seal ball valve is manually ground, it can only be used until the valve core and sealing ring are completely consistent.

Therefore, its sealing performance is reliable; the switch is light; because the bottom of the sealing ring of the hard sealed ball valve uses a spring to tightly hold the sealing ring and the valve core together, the switch is very light when the external force exceeds the pre tightening force of the spring; the service life is long.

Gate valve: lightweight, the body is made of high-grade nodular cast iron, the weight is about 20% ~ 30% lighter than the traditional gate valve, convenient for installation and maintenance; flat bottom gate seat; the whole body is covered with glue, not easy to fall off and has good elastic memory; precision casting is used for the precision casting of the valve body, and the precise geometric size makes the valve body without any finishing to ensure the tightness of the valve.

3. Operation Differences of Gate Valve vs Ball Valve

A ball valve uses a rotary ball with a bore and a stem as seen in Figure 1. When the handle attached to the stem is turned, it rotates the ball to open or close the valve. This valve is also called a quarter turn valve because the handle only needs a 90° turn (quarter turn) to allow or block the flow of the media. The valve is open when the handle is parallel to the pipe and it is closed when the handle is perpendicular to the pipe.

A gate valve uses a gate to control the flow of the media. A gate is a solid disk structure that is connected to the stem. The gate is lifted to open the valve and is returned down to its original position to close the valve. The valve is accompanied by a bonnet which when rotated controls the position of the gate. This valve is also called a multi-turn valve because it takes more than a 360° turn to fully open or close the valve.

4. Common Application of Gate vs Ball Valve

Ball valves and gate valves are both extensively utilized in residential and industrial applications. However, these two types have differences in their usage:

A ball valve is better suited for applications that require rapid opening and closing speeds or during crises due to its quarter-turn on/off function. A gate valve takes longer to operate than a ball valve since it requires more than a 360° turn.
Gate valves are commonly found in older plumbing systems that do not require frequent shutoffs. They are used in large water supply systems because of their direct flow path and lack of flow constraints, whereas ball valves are increasingly being employed in new plumbing systems that require frequent shutoffs.
Low-pressure applications are suited for both ball and gate valves. A gate valve, on the other hand, is better suited to high-pressure applications. This is due to the ball valve’s rapid opening and closing, which can create a water hammer.
Since gate valves are easier to clean and maintain, they are commonly employed with slurries and viscous media while ball valves are not ideal for this end; because they are hard to clean, and slurry particles can harm the rotary ball.
Ball valves are frequently utilized in fire suppression and marine applications. Ball valves are hard to clean and may cause contamination, thus they are best avoided in food, beverage, and pharmaceutical applications.
Gate valves are utilized in high-temperature, high-pressure settings such as power plants, mining, and water treatment.

Are Ball Valves Better than Gate Valves?

To settle the ball valve vs gate valve debate, we opened up the discussion to leading Scottish industrial valve distributors, BM Engineering Supplies, who stock both valve types. They stated that the benefit of a ball valve vs a gate valve is that they seal much tighter, therefore making them better at avoiding leakage than gate valves. This is due to their 100% shut-off characteristics. In addition, they are also easier to use than gate valves, offering both lower rates of failure and greater longevity.

The durability of ball valves makes them an ideal choice for shutoff applications. They perform consistently well after many cycles, as well as boasting reliability and the ability to close securely even after long periods without use. For these reasons, they are often preferred over gate and globe valves.

ZECO company supplies both ball valves and gate valves with high quality. Click to know more about our ball valves for sale and gate valves for sale. We are sure to provide you with the best service.

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Gate Valve Working Principle – Surface Valve Manufacturers

Jerry — Thu, 30 Dec 2021 07:05:20 +0000

A gate valve is a type of valve which restricts fully the flow of fluids. Or, valves that give full bore flow without change of directions.

Gate Valve Working Principle | How does a Gate Valve work?

A gate valve refers to a valve in which the closing member (gate) moves in the vertical direction of the centerline of the passage. The gate valve can only be used for fully open and fully closed shut-off in the pipeline, and cannot be used for adjustment and throttling. A gate valve is a kind of valve with a wide range of use. Generally, DN50 cut-off devices are selected for use, and sometimes gate valves are also used for cut-off devices with small diameters. The gate valve is used as a cut-off medium, and the whole flow is straight when it is fully opened. At this time, the pressure loss of the medium is minimal. Gate valves are usually suitable for working conditions that do not need to be opened and closed frequently and keep the gate fully open or fully closed. Not suitable for use as regulation or throttling. For the high-speed flowing medium, the gate can cause a vibration of the gate when it is partially opened, and the vibration may damage the sealing surface of the gate and the valve seat, and the throttling will cause the gate to be eroded by the medium.

From the structural form, the main difference is the form of the sealing element used. According to the form of sealing elements, gate valves are often divided into several different types, such as wedge gate valve, parallel gate valve, parallel double gate valve, wedge double gate valve, etc. The most commonly used forms are wedge gate valves and parallel gate valves.

The gate has two sealing surfaces. The two sealing surfaces of the most commonly used wedge gate valve form a wedge. The wedge angle varies with valve parameters, usually 5 degrees. The gate of the wedge gate valve can be made into a whole, called a rigid gate; it can also be made into a gate that can produce slight deformation to improve its manufacturability and make up for the deviation of the sealing surface angle during the processing. The plate is called an elastic gate.

When the gate valve is closed, the sealing surface can only rely on the medium pressure to seal, that is, relying on the medium pressure to press the sealing surface of the gate to the valve seat on the other side to ensure the sealing of the sealing surface, which is self-sealing. Most gate valves adopt forced sealing, that is, when the valve is closed, the gate must be forced against the seat by an external force to ensure the tightness of the sealing surface.

The gate valve of the gate valve moves linearly with the valve stem, which is called the lifting stem gate valve (also called the rising stem gate valve). Usually, there is a trapezoidal thread on the lifting rod, through the nut on the top of the valve and the guide groove on the valve body, the rotary motion is changed into linear motion, that is, the operating torque is turned into operating thrust.

When the valve is opened, when the lift height of the gate is equal to 1:1 times the valve diameter, the fluid passage is completely unblocked, but this position cannot be monitored during operation. In actual use, the apex of the valve stem is used as a mark, that is, the position where it cannot be opened, as its fully open position. In order to take into account the locking phenomenon due to temperature changes, it is usually opened to the top position, and then back 1/2~1 turn, as the position of the fully open valve. Therefore, the fully open position of the valve is determined by the position of the gate (that is, the stroke).

Gate Valve Parts Name

Handwheel
- This is a wheel that is rotated clockwise and anticlockwise.
Stuffing box
- A chamber in which the packing is compressed.
Packing material
- A gasket is required for a reliable seal between the stem and the bonnet. This is known as packing. This consist of the following components
Bonnet
- The bonnet is the cover for the opening in the body and is the pressure valve’s second most important boundary. Bonnets, like valve bodies, come in a variety of styles and models.
Gasket
- It is fitted between the body and the bonnet.
Stem
- The valve stem is responsible for the proper positioning of the disk and provides the necessary movement to the disc, plug, or ball for opening or closing the valve. On one end, it is connected to the valve handwheel, actuator, or lever, and on the other end, it is connected to the valve disc. The disc in a gate or globe valve must move linearly to open or close the valve, whereas the disc in a plug, ball, or butterfly valve must rotate to open or close the valve.
Flange
- It is for tightening the gland with a nut.
Gate/Disk
- Depending on its position, the disc allows, throttles, or stops the flow. In the case of a plug or a ball valve, the disc is referred to as a plug or a ball. The disk is the third most important primary pressure boundary. When the valve is closed, the full system pressure is applied across the disk, and as a result, the disk is a pressure-related component.
Valve body
- The primary boundary of a pressure valve is the valve body, also known as the shell. Because he is the framework that holds all the parts together, he is the most important component of a valve assembly.