What we need to know about industrial valves!

What we need to know about industrial valves!

What we need to know about industrial valves!
The valve is a mechanical device for closing or in other words changing the pressure of the fluid flowing through it. The act of adjusting a valve by moving the valve-shaped element (spherical, samovar, sliding, disc, etc.) located on the bar outside the valve body is a basic definition of a valve and shows that the valve is in fact a device It has a body that holds the fluid pressure, a valve to close or regulate the passage of fluid through the tube, and finally a handle to change the position of the valve. Today, industrial valves play a role in a variety of processes. Here is what we know about the five main functions of milk.

1 - Open-closed operation. This figure actually shows the passage of fluid or not. In this operation, the valve must close the fluid path with the middle part. They are sometimes called blocking valves. In addition, this function is common to most lions.

2 - fluid control. In this service, the valve does its job to change the fluid flow by changing the flow velocity or creating a pressure to reach the required goal. In this study, abundant and accessible information about sliding and spherical toggle valves and other types of valves will be described.

3- Flow deflection (change of flow direction) Fluid flow is determined by using multi-directional valves. This type of service mostly uses three-way milk, of course, four-way and five-way types can also be used, but the number of ways may be more in proportion to the use of that milk.

4 - Two-stage closure. In discontinuous control systems we need a two-stage control. This can be done using two parallel bypass flow valves. When two valves are open, the flow passes. If one of them is closed, the other current is reduced and slowly reaches the required measurement level. When two valves are closed, there will be no flow. In some cases there are control systems that work with only one valve.

5 - Mixing. When two valves are connected in a T-shape and controlled by an actuator, it can be used for a two-fluid mixture. Its important application is to achieve a specific temperature for the fluid.

A valve is a device used to control the flow and pressure of fluids. The main functions of industrial valves are:

1) Complete disconnection and connection of current
2) Prevent the return of liquids and gases passed
3) Adjust the passage of the required amount of liquids and gases
4) Adjust and control the amount and pressure of liquids and gases
5) Control and keep devices under pressure
And valves are generally used in cases where there is a pressure difference for the flow of fluid (both liquid and gas).


The first man-made valves were what we now know as a seal. A valve that, by placing or removing it in the path of water, closed the flow, leaving it open or half open. Today's gate valves are actually the same as the old seals.


Depending on the application, the materials used to make the milk will vary. Cast iron, bronze, brass and sometimes steel (SS) valves are used in construction. In industrial works such as power plants, petrochemical plants, refineries, shipbuilding and pharmaceutical / food industries, depending on the fluid passing through the valve or the environment in which the valve is located, the body and other components are made of carbon steel, alloy steel, They make stainless steel. The valves are opened and closed either by hand or by an automatic actuator.

Important points in designing and manufacturing valves are:

1- Launching force and special launching equipment
2- Vibration of milk
3- Cavitation
4- Impact on flow
5- Pressure tolerance
6- Sealing and consumables in dams
7- Ease of repair, maintenance, installation and adjustment
8- Relaxation pools

Different types of lions

1) Manual valves that work with manpower
2) Automatic valves that work with controlled air force, liquids and gases control valves
3) Automatic valves that work with electricity. Electric motor operated valves

The valves examined in this section are:

1) Needle valves
2) Samovar valves plug or clock valves
3) globevalves
6) Sliding gate valves
7) Diaphragm valves
10) Non return or check valves
11) Butterfly valves
12) safety valves
13) Drain milk
14) CROSS GLOBEVALVE three-way manual valve
19) Automatic control valves

1) Needlevalves needle valves

Needle valve, which takes its name from the shape of its disc and seat, is a member of the spherical valve family in terms of construction and workmanship. With these valves, precise control of fluid flow can be established, especially in narrow and thin pipes. The structure of this valve is such that the flow is directed to a small hole and after rotating 90 °, it is directed to the tip of a cone, and as the figure shows, the current passes through this hole and a needle-shaped piece to the outlet. The valve of this type of valve consists of a thin conical rod that passes through the circular hole of the plate and restricts the flow of fluid. The construction of these valves is mostly used in carburetors. This type of valve is very delicate in terms of construction and almost small, and due to its reliable mechanism, it is used in sensitive and precise operations. It is widely used in oil or petrochemical laboratories and instrumentation. Needle valves usually do not exceed 2 inches in diameter, and needle valves are mostly used in places where restrictions are necessary, and the limit means time delay and gentle change of pressure.

2) Samovar valves plug or clock valves

These valves are for low flows and are made in three ways: Pesvar valves are of this type. This type of valve consists of a rod in the middle of which a hole is created for the passage of water flow and in the middle of a chamber which is machined and polished on its inner surface. These types of valves, like gate valves, have very little resistance to water flow. To open and close the samovar valve, it is enough to turn the handle 90 degrees. These valves are usually used as a two-state control device (switching on / off). Because (1) they are relatively inexpensive, (2) they remain the same when adjusted, and (3) employees can clearly see whether they are open or closed. If the surface area of ​​the ORIFICE valve is equal to the cross-sectional area of ​​the pipe, the efficiency of the valve as a flow control device will be reduced.

3) Globe valves

This valve takes its name from the spherical shape of its body, which is spherical in shape, and its internal structure is such that the liquid changes direction 180 degrees from the point of entry into the valve to its exit. The construction of the valve and the seat is such that as soon as the flow of contact between them is interrupted, the complete absence of the spherical valve does not cause it to wear out. Therefore, it can be used to regulate and control the flow. Proportion of the number of revolutions of the valve handle to the volume of the liquid outlet makes it easy to adjust the amount of flow by hand.

The characteristics of spherical valves include the following:

The direction of fluid flow changes unlike a sliding valve.
Changing the direction of fluid flow causes turbulence.
Turbulence increases the pressure drop.
In a spherical valve, the pressure drop is greater than in a sliding valve.
In a spherical valve, the fluid flows completely as soon as the end plate of the stem and the seat are disconnected
Spherical valve wear is much less due to friction than sliding valve.

One of the types of spherical valves is angular spherical valve in which the change of fluid direction is less than ordinary spherical valve and the fluid turbulence in angular spherical valve is less than ordinary spherical valve. Finally, in the case of spherical valves, it should be said that this type of valve is designed to control the fluid, and due to the sudden change in the direction of the fluid, opening and closing the valve is done much faster. It should also be noted that the various materials used to make them are available. And their repairs are less and easier than sliding valves, so that they can be repaired without removing them from the piping path, and the valve material is often made of nickel or stainless steel.


This type of valve is the same as a spherical valve, with the difference that there is a 90 degree angle between its inlet and outlet. This type of valve causes less pressure drop than a spherical valve and also due to its special shape, in the use of piping fittings and It also saves time required for installation.


These types of valves are also called impact valves. The flow of water in this type of valve passes through the hole of a spherical ball which is in a perfectly polished spherical position. To open and close this type of valve, like samovar valves, only a 90-degree rotation of the handle is enough. These valves also provide little resistance to water flow. These types of valves can be used in hot and cold water piping as well as low pressure gas piping.

6) Sliding gate valves

These valves are mostly used in places that want to completely close or open the fluid flow. One of the properties of these valves is the low pressure drop during it


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