In fact, the valve is shut-off and control valves. A mechanical device serving to pass, overlapping or adjustment Incoming liquids, vapors or gases through the pipeline. From the above, such a product can be called periodic obstacle located within the tube. Valve sizes can be calculated to several centimeters or a few millimeters. Exact parameter settings depend on the pipe on which it is installed. The structure may be secured to the pipeline by means of threaded, flanged or welded connections.
Pipe fittings has been widely used in various technological applications. Having made a crane rotation, adapted to the pipe outgoing from the plate, it is possible to regulate the gas consumption, and a valve mounted on a vehicle bus, facilitates its pumping air, preventing the air outlet out. A crane, mounted inside a steam radiator, makes it possible to bleed the air and replace it with steam located there.
Key details
The apparatus control valve comprising: a housing lid (head), the saddle, the shutter (shutter) and a rod (spindle) with flywheel. Sometimes the flywheel can be replaced by an automatic device. All the components are combined by means of the body. Working matter is fed inwardly through the device housing. The spindle is located in the head (here located sealing gland), causes the shutter to move, thereby opening or closing hole on the saddle. Working composition, acting through it, coming out the other side. Flow may be direct or wrapped.
Materials for the production
To produce such structures using materials that meet the necessary requirements, put up for a particular type of tubing and working compositions.
The valve can be manufactured using the following materials:
- iron forging or cast (gray);
- Stainless or carbon steel;
- bronze;
- Inconel, Monel and other metals, including nickel base.
Materials that are suitable for such production are characterized as low, and the degree of resistance to temperature changes and the formation of rust.
Gray cast iron, for example, in most cases manufactured shoddy device. Bronze, because of its high resistance to corrosion is used for working with corrosive materials. Carbon steel, the most robust of these metals are used where high pressure is maintained. Chrome refractory material used in the industries where the temperature may rise to 600 ° C.
Valves, consisting of the above metals are used for equipping urban hydraulic systems. Elements, mounted inside the structure, can be manufactured from the same alloy as the body, and They may consist of plastic (most often used in gravity models) and rubber materials.
To improve the seal and the sealing seat, the valve stem and gate, in most cases, used graphite, cotton, rubber or Teflon (it depends on the types and contents temperature pipes, as well as the conditions in which the use device).
varieties valves
Structure with a linear movement of the gate or gate (valve) is often used for pipelines. Such industrial valve is called the gate. It can be completely closed or opened. Open enables the flow of matter passing through the pipeline almost unimpeded.
The valve mechanism, when compared with the damper, significantly hinders the promotion ended pipes. Pressure drops occurring across the valve, are applied to resolve the matter or the flow pressure within the conduit.
The valve mechanism is provided with a rotating spindle. When the flywheel rotates, the spindle is moved relative to the head of the thread. As a result, lifting or lowering the shutter.
Needle assembly is small. The shape of the needle assembly workspace rod resembles a cone, allowing no runs adjust the flow rate of the working substance.
The valve membrane appears as a valve in which the spindle (between the body and head) is a flexible membrane. Under the influence of the diaphragm rod, moving, or adjusts the current position of the mechanism, or completely overlapped. The movable components of the mechanism do not interact with the fluid flow, because the membrane does not need to replace the shutter or sealing materials. Purpose membrane devices - interact with liquids containing solids or corrosive environment are carriers.
Assigning the return mechanism - to prevent recurrent promotion of the fluid inside the pipe. It is known that there are two main types of check valves. They can be hinged and elevating. The first provided with a hinged flap, attached above the seat. Under the influence of the flow coming from the apertures, the damper opens, and the liquid penetrates freely through the valve. If the flow will change the direction of motion, the shutter lowers and closes the opening tightly pressing against the seat by fluid pressure. Lifting the flap operates on a similar principle, moving into the vertically placed cylinder guide. When the flow changes direction, the flap lowers and tightly pressed against the seat.
Called single seat poppet valves, operable by "cams" and levers, and by the action of closing springs. Motorists using such devices for supplying fuel and air in cylinders of the engine and vehicle and also used for discharging gas. Described poppet mechanism installed in some types of steam engines and steam turbines as a means for controlling the supply of steam.
Bellows valve has a corrugated structure of metallic materials. This product retains its strength and tightness under repeated compression, tension, bending. Applicable pipeline valves as a sealing, the strength member.
To protect against mechanical damage to the pipeline is too high pressure impulse valves are used. By automatic release of passing fluid from the systems they reduce the effect of the increased pressure.
Purpose reducing device - lowering the pressure inside the pipeline. The value of the orifice varies automatically. Inside it is equipped with a moving rod and a special device, through which can be repositioned relative to the seat.
Regulating device in most cases manufactured as a profiled part. In simple models SETTLED pressure acts on the membrane, which is fixed on the rod. By means of a spring or Booting pressure is balanced, and its strength is changed when changing the spring tension during movement of the weight on the lever. The membrane, typically under the influence of pressure of the flow coming above or below the valve. The actuator, in most cases, not necessary.
Where necessary the regulation of coolant applied four way type device. To achieve the desired temperature in the system can be only one way - by mixing hot and cold medium, to yield the desired result. Successful completion of this process, and provides four-way valve.
The valves are equipped with a rotating bolt
Products throttle-type need to adjust or overlapping access to natural gas, liquid or two-phase flow. Thin flap resembles two bowls stacked together. In the through hole of the throttle device may be a sealing layer of a soft material. The spindle moves relative to the damper. When closing the valve prevents the passage of the stream, taking a perpendicular position and firmly adhering to the soft cushioning material disposed within the housing. When the throttle valve is opened, therefore, the damper is arranged parallel to the flow.
The regulatory part of the ball valve is like a balloon with a through hole. Under the influence of the spindle to be rotated with an amplitude of 90 ° C. When the mechanism is open, which means that the outer ends of the through hole on the ball with the holes on the saddle. When it is closed - the holes in the ball does not align with the holes in the saddle, and the saddle are covered because the tightly adjacent to the surface.
Regulatory mechanism is somewhat similar to a pressure reducing. It is equipped with a special drive (usually - electrical or pneumatic), paired with an automatic controller. With regards to the characteristics of the control valve control unit, it may be noted that in fact, it is a device for measuring fluid flow, temperature or pressure and then comparing these values with the level of required. From the control unit is commanded by obeying which, working organ receives the desired position. Moving element within the indirect action of the valve may be of translational or rotational in nature. By design adjustment mechanism may be a valve or throttle type.
Through the control valve can control the flow of matter and the level of pressure, so the mechanism is almost never fully open or closed. Since it is used for throttling the flow (process, which is characterized by reduction in pressure). The material from which the control device is manufactured, must be of high resistance to erosion. Lowering the pressure sometimes cavitation ends (in the case of liquid substances) and noise (in the case of steam or gas flow). Modern control valves have a high resistance to cavitation and noise, making them suitable for use in the most adverse conditions.