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Comparative characteristics shut-off valves

General characteristics of different types of shut-off valves

Shut-off valves are used in the installation of gas pipelines and sewer systems. It can be seen on general purpose, industrial type, industrial pipelines with special conditions work, plumbing pipelines and many others. They are designed to block any water or gas flows.

For these purposes, a gate valve, tap, valve, valve, as well as other locking mechanisms are used. Household plumbing cannot do without such mechanisms, but few people understand the difference between a faucet and a valve. Without this it is simply impossible to connect household appliances, fix the leak, turn off the gas or change the mixer. Plumbing surrounds us all around us, and shut-off valves are an integral part of it.

In fact, it has significant differences, both design and operational, although any constructive solution This type of valve always works in two positions: closed and open.

But, based on their functional characteristics and scope of application, one or another type of device is selected. For the right choice you should know how the principle of their operation may differ, and what function each of them performs.

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Operating principles of taps, valves and gate valves

Design solutions for shut-off valves are taps, valves and gate valves. How are they different from each other?

Gate valves are the most common and most popular locking devices. Their design implies that the locking element is in the closed and open position. Flow working environment overlaps due to the fact that the locking element moves perpendicular to its axis. Gate valves can be used exclusively as locking valves. They are parallel, wedge and gate.

A valve or valve is capable of blocking the flow of the working medium due to the fact that the device moves parallel to the axis of its movement. It, unlike valves, can be used not only as a shut-off device, but also as a regulating device due to the fact that its design will allow you not to completely block the flow of the medium, but partially.

TO significant disadvantage may be attributed to the valve's inability to respond to changing speed and pressure in the system. Therefore, its scope of application is pipelines with a relatively constant flow and pressure of the working medium. In addition to regulating and shut-off devices, there are bypass, mixing, and distribution structures these mechanisms.

A faucet is another type of shut-off valve. It can be used as a shut-off or a regulating device. It functions like this: the locking element, rotating around its axis, moves in a direction perpendicular to the movement of the medium flow. The locking element has the shape of a disk. Due to its rotation around its own axis, the liquid overlaps in a perpendicular direction.

Modern plumbing offers various design solutions for shut-off valves, which have their own characteristics. Of course, this entails the presence distinctive advantages and shortcomings that appear in different conditions. Therefore, in order to choose the right shut-off valves, it is necessary to take into account the design features of the pipeline, as well as the conditions of use and requirements for a specific device. To do this, you need to understand the difference between, for example, a faucet and a valve, because the difference between them is not so obvious.

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Comparative characteristics of tap and valve

The main difference between a faucet and a valve is the adjustment of the pressure of the working medium. The valve can make such adjustments, but the faucet cannot. Moreover, taking into account the operating rules of taps, it is strictly prohibited to regulate the pressure using them. The tap has only two functions: open and close the flow of the medium. But the valve can easily regulate the pressure of liquid or gas.

This difference is due to design. The shut-off element in this device moves in the direction of flow and eventually sits on the seat. In cranes, it rotates around its axis. In addition, there are ball valves. In their design, the shut-off element is a ball that rotates perpendicular to the flow, as a result of which the diameter of the pipe changes. But the valves are equipped with a ground axle box. This design solution implies that by moving the axlebox rod, the valve, which is attached to the rod, is raised or lowered. Thus, the opening or closing of the hole located in the seat occurs.

Visually, it is easy to distinguish a valve from a faucet. If the shut-off valve has a simple handle, and the end of this handle is attached to the stem, then it is a faucet. If there is a thumb in place of the handle on the rod, it is a valve.

The most popular structures today are taps and valves. Many do not understand the differences between these two types of shut-off valves and are guided by the advice of sellers and friends. Sometimes you can even see the influence of fashion. For example, 10 years ago everyone switched from valves to taps, but now it’s the other way around. However, both of these types of fittings have their own individual characteristics.

Gate valve

The operation of the valve is to block the flow of liquid or gas with a locking element. The overlap is made perpendicular to the flow.

The design of the valves is simple, and they themselves are quite unpretentious in operation. Valves in open form have low hydraulic resistance. The valve works perfectly with viscous media, passing it in all directions. One of the most popular brands of valves is AVK (avk official website Russia).

Now about the cons. It is difficult to regulate the flow with a valve. The locking element has only two positions. Either closed or open. To withstand high pressure, the fittings must be strong and massive. The locking element wears out over the years, and its repair is very difficult and often requires a complete replacement.

The valves are:

• Wedges. Its sealing surfaces are at an angle to each other, which ensures good contact regardless of temperature and even corrosion.
• Parallel. Here, accordingly, the sealing rings run parallel. They are used where there is no need for 100% tightness.

Cranes

The closing part of the faucet is made in the form of a rotating element with a hole through which the medium passes. Valves are available in conical, ball and cylindrical types. Today, the most popular is considered to be a ball valve. Turning the plug can regulate the supply of medium from reducing the flow to completely blocking it.

The taps can operate with both liquid and gas. Unlike gate valves, they are more compact.

The weak point of any faucet is the seals, which, when worn, destroy the entire seal. Also, due to non-metallic seals, the faucet cannot withstand various aggressive environments.

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They are used on pipelines with a large diameter, more than 50 mm, where it is necessary to slowly shut off the flow to prevent water hammer.

At the valve, the valve moves perpendicularly, and at the moment of closing the sealing surfaces do not experience friction, which significantly reduces the occurrence of scoring.

Due to the fact that inside the valve body the flow direction changes twice, and the flow area is smaller than that of gate valves, the valve has increased hydraulic resistance, which is its main disadvantage.

The valve cannot be operated in different directions relative to the flow. Its working position is the direction of flow when, in a closed state, it presses on the plate from the side of the seat, and not from the side of the rod. In this position, the flow pressure when the valve opens even helps lift the plate from the seat. At incorrect installation of the valve, the flow pressure in the closed position presses the plate, and when the valve is opened, a very significant force will have to be applied to the movement of the rod, since it will be necessary to overcome the flow pressure. This can lead to its failure, since the shutter plate can be torn off the rod, which will require large labor costs for repair.

Cranes: main characteristics

A faucet differs from a valve and gate valve in that to start or stop the flow using a faucet, it is not necessary to rotate the spindle

They do not have a rod, and their valve is made in the shape of a ball, cone or cylinder with a hole for the passage of flow and rotates perpendicular to the flow. If the axis of the valve hole coincides with the axis of the pipeline, then the valve is open, since the flow passes through the hole. If the shutter is turned 90°, the valve will be closed. A faucet differs from a valve and gate valve in that to start or stop the flow using a faucet, it is not necessary to rotate the spindle. To do this, just turn the shutter 90°. This differs from a valve to a valve. It does not have a flywheel, so it is operated by a crank. The valve is in the open state if the handle is located along the pipeline, and if it is perpendicular, it is closed.

For cone valves, the valve is designed as a truncated cone. It has a hole for the passage of flow in the form of a rectangle or circle. The valve body also has a conical surface. This was done so that the plug could fit tightly to the saddle.

For tightness, the seal is sealed with lubricant, which should fill all micro-gaps between the body and the shutter. At the same time, it reduces the force required to turn. The cork is pressed against the surface of the body.

There are two ways to press the shutter, and thereforeThere are gland and tension valves. In gland valves, between the upper end of the plug and the valve cover there is a gland packing. This is an elastic element that presses the valve to the body with constant force. Tension taps have a rod at the bottom of the plug that passes through the body hole. The shutter is pressed by a spring. Such taps are more reliable, since they do not have gland packing, the elastic properties of which are lost over time. Therefore, in such important industries as gas supply, tension cranes are used.

Cone valves are low cost, they are not difficult to inspect, they have a simple design and relatively low hydraulic resistance. This is their advantage

But such cranes also have disadvantages. It takes a lot of force to turn the plug. Over time, the microgaps between the shutter and the body surface become covered with deposits. In this case, turning the valve requires a lot of force, which can lead to breakage of the tap.

The production of taps requires a high-quality processed surface of the valve and body, so they are made of bronze and brass. In addition, these metals are less susceptible to corrosion, which extends its service life.

The most common locking devices include valves and taps. What is the specificity of both?

What is a valve?

Under valve It is customary to understand a shut-off mechanism on a pipeline, which involves blocking the flow of liquid or gas through a partition. It can move across the pipe up and down or left and right. In many cases, the valve also allows you to regulate the intensity of the flow of liquid or gas. For example, if the valve partition is moved halfway, the flow intensity is reduced by 50%. As it moves higher or to the left (or lower or to the right - depending on its initial position), the intensity of the flow can increase or decrease.

The partition on the valve is most often made in the form of a disk, sometimes a wedge or a sheet. There are valves in which the partition consists of one element, but in some cases it is represented by several parts. For example, if there are two of them, increasing the intensity, or opening the flow, can be accomplished by moving them apart. Reducing the dynamics, or closing the flow, on the contrary, is carried out by closing the components of the valve partition.

The main advantage of the valve is the ability to open or close the flow relatively quickly and with relatively low energy costs (or set its desired intensity).

Valves can be installed on pipelines with high pressure - for example, heating, water supply. They are among the most airtight locking elements.

With frequent use, a valve can wear out quite quickly - this is due, in many cases, to a fairly large friction force between the edges of the partition and the block in which it moves left and right or up and down.

Another disadvantage of the valve is the need to allocate additional space outside the pipeline cross-section in order to temporarily accommodate the moving part of the partition. Installation, maintenance and repair of the locking element in question can also require quite a lot of labor.

Thus, taking into account the noted advantages and disadvantages, the valve is most often used not as an adjustment element, but as a locking element, which is supposed to be placed in the “open”, “closed” or other static position for quite a long time. In order to frequently regulate the flow of liquid or gas in pipelines, another shut-off device - a tap - can be successfully used. Let's consider its features.

What is a faucet?

Tap- this is a locking element, the main part of which is a shutter, presented in the shape of a ball, in the form of a cone or a cylinder. They have a channel with a diameter that is sufficient to ensure the passage of flow if the corresponding channel is located parallel to the flow or is located at a slight angle to it. In turn, when the channel is placed perpendicular to the flow (by rotating the ball, cone or cylinder in which it is made) or at a large angle to the flow, the movement of liquid or gas in the pipe stops or its intensity decreases.

Changing the position of the valve is carried out by rotating a spherical, cone-shaped or cylindrical valve around its axis perpendicularly or parallel to the flow (this is not important, the main thing is to achieve the necessary tightness).

The faucet, like the valve, is characterized by a high degree of tightness. Therefore, it can be installed on pipelines with high pressure. At the same time, cranes are not characterized by the main disadvantage of valves - wear. Provided that the locking device in question is properly lubricated and maintained, it can last a long time.

The valve is thus excellent for regulating the rate of movement of liquid or gas in a high-pressure pipe. This explains its frequent use as a locking mechanism at the final section of pipelines. For example, as the main element of household faucets, which are located in bathrooms, kitchens, and showers.

A crane, as a rule, does not require a large space outside the cross-section of the pipeline, since its main element - the valve - rotates around its axis within the pipe. True, additional space may be required for the control valve and other mechanisms that complement it.

Comparison

The main difference between a valve and a faucet is that the main element of the first shut-off device is a partition that moves perpendicular to the flow of liquid or gas in the pipeline. The main element of the faucet is a valve with a channel made in it, which, when placed parallel to the flow or at a slight angle to it, increases the intensity of fluid movement in the pipe, and when placed perpendicular to the flow or at a large angle to it, reduces its intensity.

The difference between the considered types of locking elements can also be traced in the following aspect:

• wear;
• requirements for spaces outside the pipeline cross-section;
• scope of application, prevalence of inclusion in the structure of household faucets.

Having determined what the difference is between a valve and a faucet, we will record the conclusions in a small table.

Table

Gate valve	Tap
What do they have in common?
Gate valves and taps provide high tightness to block the flow of liquid or gas in a pipeline, suitable for high pressure pipes
What is the difference between them?
The main locking element of the valve is a partition that moves left-right or up-down (unless it is represented by a more complex - for example, double-leaf design)	The main shut-off element of a faucet is a valve that can rotate around its axis and place the channel made in it at a greater or lesser angle relative to the flow of liquid or gas in the pipe
Wears more intensely with frequent use	Less wear and tear with frequent use
As a rule, it requires significant spaces outside the pipeline cross-section to accommodate the extending part of the partition	Requires spaces outside the pipeline only for the purpose of placing control elements - valves and their complementary mechanisms
It is mainly used as a typical locking element that is in the “open”, “closed” or other static position for a long time	It is used as a control element, through which you can set the desired flow rate in the pipeline at any convenient time
Generally not used as a component of household faucets	Is one of the main components in household faucets

For specialists working in industrial enterprises, it is important to know the differences between a faucet and a gate valve.

general information

A valve is a drive fitting used for the manufacture of a pipeline, where the gate valve rotates around its own axis in a perpendicular direction. The element includes two components:

• Movable type cork;
• Static body.

Fig 1. How the structure is arranged

A valve is a drive-type fitting where the structure moves along the flow and fits onto the seat. Designed for direct opening or closing, regulating the flow of any medium.

What are the main differences

It is customary to distinguish three types of fittings depending on their purpose:

1. Driven.
2. Regulating.
3. Constipated.

Some classifications add a safety group.

Considering the main differences between a valve and a ball valve, it is worth noting that in the first mount it is possible to adjust the fluid flow. A ball valve is not capable of performing this task. Based on current regulations, controlling and changing the flow of liquid using a ball valve is strictly prohibited by safety regulations. This is primarily due to the limited functions, since the regulator can only open or close the flow.

With the help of a valve, changes in the operating pressure are allowed due to the water pressure in the pipelines.

It's all to blame design differences, defining the functions and uses of the elements. Considering the main elements of the fixed valve body, the shutter mechanism in it “sits” on the seat. Its movement is carried out in the direction of the flow.

When operating a crane, turns are carried out around its own axis. If needed additional elements, plumbers use ball elements. When the ball begins to rotate, the diameter in the hole automatically changes.

The valve is equipped with a ground box. When the stems are screwed in/out, the valve moves up and down.

Comparing both designs, several conclusions can be drawn:

1. The valve is in the closed and open positions.
2. The valve is also capable of regulating the pressure.
3. To visually recognize whether it is a valve or a faucet, just pay attention to the handle. The faucet's structure is quite simple, unlike the valve (here it is presented in the form of a lamb).

When considering the main types of shut-off valves, it is recommended to consider another popular element - the valve.

There are several types of cranes, based on the body of rotation:

• Conical. Visually resembles the shape of a truncated cone. The hole can be seen in a rectangular or round shape. Most often used in gas supply. Popular due to its price.

Fig 2. Cone

• Cylindrical. Chief regulator of the heating system. Can perform vertical movement to regulate fluid flow.

Fig 3. Cylindrical

• Ball. No plumber can do without it. The hole is made in a round shape through which the medium passes.

Fig 4. Ball

Why do you need a valve, the main advantages and nuances

A type of fitting where the adjustment part moves in a perpendicular position, moving in the direction of flow. Among representatives of this category, the valve is considered more relevant.

Fig 5. Gate valve

The tool is popular in use:

• Transport activities, where the diameter of products ranges from 15-2000mm;
• In creating water and gas supply;
• In the housing and communal services sector;
• Oil production.

The prevalence of the use of valves is due to the following aspects:

• Easy to operate;
• Small sizes;
• Allows operation in various conditions;
• There is a slight resistance in the hydraulics.

The last aspect is important when constructing highways. Constantly carried out in an environment characterized by high speed.

The mechanism is not without serious nuances. Experts in choosing necessary tools and materials, it is not recommended to use designs where the spindle is retractable. The shutter stroke is at least one diameter.

It is customary to distinguish two types of valves:

• Full bore.

Fig 6. Full bore

• Narrowed.

Fig 7. Narrowed

The first one is the most common. In it, the full bore diameter is equated to the value of the pipeline on which the tool is installed. To reduce the amount of torque, valves are used to control the control of valves, including reducing the wear rate of other pipeline components.

There are several principles for controlling valves:

• Manually;
• By means of an electric drive system;
• By means of a pneumatic drive system;
• Through a hydraulic drive system.

Considering comparative characteristics between a tap and a valve, we can conclude that both elements have a number of similar features and differences.

comparison table

Criterion	Gate valve	Tap
General signs	They are used to create tightness during the movement of liquid and gas flow in a pipeline. Ideal for high pressure structures
What are the differences	The movement of the main element (partition) is carried out in all directions: right, left, up and down	The shutter acts as the main element. It can make movements around its own axis, and also place the channel at different angles relative to the fluid flow
	Wear occurs intensively with constant use	Less wear and tear even with constant use
	It is necessary to calculate additional space outside the pipeline creation to accommodate part of the partition	It is necessary to calculate additional space only for the placement of regulatory elements
	In practice, installation and operation of the device is most often found as a locking element, in the open or closed position.	As a traffic controller. At any time, it is enough to set the required intensity to ensure uniform flow movement
	Rarely used as a component in a mixer	Acts as one of the main elements in the mixer.

The tap and valve are very tight. This is why plumbers use them during plumbing repairs. However, the crane is characterized by less wear than that of gate valves. They can be used longer only if the following basic conditions are met:

• high-quality periodic maintenance,
• optimal lubrication.

Based on this table, we can conclude that the main differences between the two mechanisms can be traced in the following indicators:

1. How quickly parts wear out.
2. The amount of free space that will be needed outside the pipeline structure.
3. Where can it be used?

The tap copes well with the role of a regulator, and can also act as an auxiliary element in regulating the supply of water or gas when high blood pressure. Therefore, when creating a pipeline, taps are often found at the end sections. Since the rotating element moves around its own axis, it does not require much space. But the control mechanisms will require space to place the valves.

A distinctive characteristic of mechanisms is the type of main mechanism. This is a system that moves in a perpendicular direction in a pipeline. The main element in the tap is a special valve. If it is placed parallel to the flow or at a small angle, the intensity of the movement of liquid or gas increases; if it is placed perpendicularly, the intensity decreases.