A water valve is necessary in order to regulate the flow of liquid, which moves through the pipes by changing the flow area. Such structures are attached not only at the edges of plastic pipes, but also in places where filters, pumps and other devices are connected. The type, dimensions and modification of the part will depend on the area of the valve attachment, as well as on the functions it performs.
Popular valve valve models
The installation of a plumbing system made of plastic pipes to the main water supply cannot do without the use of a valve tap. Experts distinguish three classification components of plumbing fittings:
- the design of the main cylinder (body);
- the type of hermetic separation of the pipeline system;
- a plan of how the mechanism is installed in the system.
Water taps and valves are able to withstand the same pressure that is applied to the pipes, therefore it is strongly not recommended to use structures with low strength in comparison with the entire system.
The manufacturer puts the factory parameters on the mechanism case, and its modification depends on the functions of the product.
In order to connect the control and measuring device, it is recommended to use an angle needle-type valve with a small through hole. The household tap provides a convenient and regulated drainage of the liquid. Today, ball and valve types of valves are popular, and due to the simplicity of design and ease of operation, such mechanisms are distinguished by many positive reviews.
Due to the long term and operation plan, shut-off valves are used both in water supply and gas networks, and with the help of a unique design, it is possible to easily regulate the flow of liquid or gas. The main disadvantage of a ball valve is that it cannot be repaired even with the slightest breakdown.
As for the valve fittings, they are shut-off and control valves, many use them in order to change the water flow over a wide range.
The key characteristics of this type of valve are its large dimensions, as well as moving parts that are located in the locking mechanism.... Of the shortcomings, a short service life can be distinguished, which is associated with the design features of the valve valve. Since rubber or leather is used to make the sealing elements, the parts quickly fail. But they can be replaced and the service life of the mechanism can be extended without deteriorating its operating parameters.
Depending on which method of attaching the water tap, the corresponding fasteners will also be used. In the household system, preference should be given to coupling joints (American women) or squeegees. Since there is a constant high pressure in the pipelines of industrial systems to prevent liquid leakage, a water shut-off valve must be installed using a welding machine.
Manufacturing technology and materials
The manufacture of coupling shut-off and control valves is carried out by casting or stamping. At the same time, the material undergoes a preliminary check for compliance with operating standards in a particular environment.
For production, stainless steel, cast iron and brass are used, which are distinguished by high performance characteristics, long service life and an acceptable cost to meet the needs of the buyer.
Brass valves
The brass coupling valve is most often used in vertical or horizontal cold water supply systems. The design of the mechanism can be:
- Direct-flow. It has no internal metal parts to be protected. The spindle axis in them is located at an angle to the flow line. At the same time, a low hydraulic resistance is observed. The valve body is long and heavy.
- Angular. Installed at the points of turn or bend of the highway.
- Direct-flow. Its installation is carried out on any section of the pipe. The device is characterized by a high level of hydraulic resistance.
Brass products are distinguished by high corrosion resistance, resistance to temperature extremes, and resistance to increased pressure inside the system.
Cast iron valves
The cast-iron coupling valve has a powerful body and a regulating unit based on a spindle. It is designed for pipes with a diameter of 10-300 mm. The body of the part is capable of withstanding pressure up to 15 MPa and heating up to + 225 ° C. In practice, the products are used in low-pressure water pipelines with a liquid temperature of about + 50 ° C. Less often - for the transportation of steam and gas with the prescribed maximum characteristics.
Due to the strength of the body and the control mechanism, cast iron cranes are widely used not only in everyday life, but also in industry. The relatively low cost makes them practically irreplaceable. The body of the product is made of gray or ductile iron. All parts of the shut-off unit are made of steel. A rubber or leather gasket is used as a sealing element.
Steel devices
The steel coupling valve has excellent strength, significantly exceeding that of cast iron and brass, but inferior to them in hardness. To improve performance, alloying elements such as manganese, cobalt, vanadium, chromium, etc. are introduced into the composition.
One of the varieties of modified metal is stainless and heat-resistant steel. The cranes have proven themselves excellently in lines with high temperatures and aggressive media.
Coupling valves with an American mechanism are made of steel, in which union nuts are used instead of hexagonal ends. This design greatly facilitates the installation process, since there is no need to rotate the entire valve. Fixation is carried out by screwing the nuts separately on each side.
Classic device design
The design of a valve or classic valve includes a movable locking mechanism with a drive, as well as a cast two-chamber body. A straight-through or straight-through valve must be installed in a straight section of the pipeline to be able to regulate and turn off the water flow. Due to the design features of the angle-type valve, it can be installed in places where the pipes will turn. The details differ from each other only in the shape of the body, and the principle of operation is the same for them.
Classic tap.
In the straight-through water tap, the liquid enters the lower cavity, which is pressure, after which it enters the upper chamber through a special hole and through the pipe it enters the consumer. The locking mechanism of the device consists of the following parts:
- spindle (stem) with thread;
- valve disc with sealing material;
- stuffing box;
- union nut and bolt.
As soon as the flywheel begins to rotate, the stem moves the disc to the lower hole, thereby reducing its cross section. This process is accompanied by throttling of the liquid, as well as a decrease in pressure in the upper chamber, which, in turn, leads to a decrease in water consumption.
The unreliable location of the plumbing part is represented by the threaded block, since excessive force during the closing process often leads to the breakdown of the threads and destroys the entire assembly. In order to seal the stem, a stuffing box seal should be used, and to eliminate leakage along the spindle, you need to tighten the union nut that presses the packing through the packing follower.
Ball valve features
The valve, which has a spherical stop switch, is a simpler mechanism, since its body is non-separable. The functions that the locking mechanism performs in the classic device here are the operation of a metal ball or valve with a hole. Between the cylinder and the spherical valve, sealing gaskets are installed, for the manufacture of which rubber or fluoroplastic is used. For higher cost models, the gaskets can be made from wear resistant Teflon seals.
Features of the ball valve.
For the manufacture of the ball, most manufacturers use brass, the spraying of which is made of nickel or chrome. These materials and the treatment of the obturator parts contribute to the complete tightness of the faucet. The valve is controlled by a manual actuator represented by a stem that is welded to the ball. To shut off the flow of water, the spherical valve must be turned 90 degrees, and the protrusions located on the valve cylinder prevent the circular rotation of the ball. These stops are also required to ensure maximum closure of the water path..
Sealing in the area where the rod exits the cylinder is achieved by installing gaskets, which are pressed against the threaded bush. The water valve drive is equipped with lowered petals that prevent the valve from turning more than ¼ of the entire circumference.
Selection recommendations
Almost all companies supplying pipe components to the market are engaged in the production of valves for piping systems. Reliable manufacturers include the following companies:
- Valtec;
- Rehau;
- Lavita and AS Gruppe.
Since these brands have been present on the market for a long period of time and have managed to prove themselves from a good side, their products are popular and also do not raise questions about quality. But in the process of choosing a shut-off valve, you should definitely pay attention to the product body, which must be made of a brass alloy.
For the manufacture of cheap Chinese products, in most cases, recycled (recycled) brass is used, which contains elements that are dangerous to the human body. It is strongly not recommended to neglect this factor and you should demand from the distributor a document certifying the sanitary compliance of the product.
When buying a valve, you also need to carefully inspect the shut-off element, since in order to reduce the cost of the product, brass is often replaced with ordinary steel, which is prone to corrosive formations. In the process of using such a mechanism, the locking mechanism becomes covered with rust, which leads to a violation of the tightness, which can cause the water supply to break through.
When choosing a ball valve, special attention should be paid to the surface of the shut-off ball, which should be perfectly smooth due to the fact that the walls of the part are processed using the diamond grinding method. If there is even the slightest roughness on the surface, the throughput of the valve fittings is impaired, and the circulation of the liquid will be accompanied by characteristic sounds.
In order to regulate the water supply, red or black levers are provided in the valve, but in any gas pipeline such a toggle switch has a yellow tint.If the plumbing will be laid in a confined space, it is recommended to opt for a compact butterfly-shaped handle.
Installing a valve in the system
Depending on which installation method is used, the valves can be flanged, welded, socket or socket. Before installing this or that water tap, you should acquire a minimum set of tools: a seal and an adjustable wrench. Threaded valves often have internal or external threads (in rare cases - combined). In the process of selecting the necessary fittings, it is necessary to take into account the diameter of the pipeline, and also take into account the fact that the valve and pipe flange may have different threads.
Before proceeding with the installation of the valve, the circulation of water in the pipeline must be completely shut off, and all the liquid from the system must be drained. When replacing the valve, the old fittings are dismantled, and the thread on the pipe is cleaned of dirt and seal residues. If defects are found on the thread (rotted 2-3 turns), the area that has been damaged is cut off with a grinder, after which a new thread is cut. The valve must be screwed onto the pipe by 4-5 full turns, therefore, the depth of the thread must be checked without a seal. Only then can the seal be wound on and the valve on the pipe can be tightened with an adjustable wrench.
The fum tape or seal should be wound in accordance with the direction of the thread. As for the thickness of the seal, it should be no more than 2 mm, and after the pipe has been wrapped, the seal must be lubricated with investment paste.
Mounting methods
Water supply valves can be connected to the process in different ways: fixed with special elements or mounted by welding.
Flange connection
This type of connection uses a special metal flange with a rubber gasket.
Free flanges are put on the end of the pipe and the valve branch pipe, a gasket is installed between them, then the entire assembly is tightened with bolts.
Coupling fittings
The connecting branch pipe has an internal thread with a fine pitch, and the outside is designed in the form of a hexagon for ease of use with a wrench. The coupling is screwed onto the thread with a linen strand seal or FUM tape.
Tsapkovaya
This mounting method is characterized by the presence of an external thread at the end of the connecting pipe and a shoulder at the end of the pipeline.
The end piece of the valve is pressed against the pipe and fixed in this position with the help of a union nut. The tightness of the connection is ensured by a metal gasket and special lubricants.
Choke
The nipple is a short length of pipe (sleeve) with female threads at both ends. With this type of connection, the connecting ends of the fittings are screwed onto the pipe and fixed with a union nut.
For welding
This is a one-piece type of connection, the tightness of which is ensured by welding.
Features of the repair work
During the operation of the water valve, the mechanism is often subject to various breakdowns. The valve may leak due to the fact that the gasket has become unusable or the shut-off element has fallen off the stem. The low quality of the metal leads to the fact that the stem gradually bends, and due to the scale between the walls of the cylinder and the shut-off unit, the valve is not able to shut off the water supply.
Carrying out repair work on the water supply system.
If the shut-off unit has lost its shape, bent or flew off the stem, the valve must be changed completely, since you can only correct the tightness of the structure with your own hands. To replace the valve, you need to twist the valve head with an adjustable wrench, and then dismantle the union nut, flywheel, stem and stuffing box bushing.After the valve is completely disassembled, a new gasket of the same diameter should be installed, then wrap the stem with a thick layer of flax and tamp it with a screwdriver.
It is necessary to install a bushing on the stem, which will press the packing, and then screw everything with a union nut. The repaired valve head must be assembled and screwed into the cylinder of the structure. After the union nut has been tightened, it is necessary to check the tightness of the mechanism. If the repair work does not bring the desired results, it is recommended to replace the water valve with a new one.
Often, for the normal functioning of the tap, you just need to clear the mechanism from blockages that impede the normal pressure of the water flow. To eliminate serious blockages, the valve must be removed completely, but small accumulations of dirt can be removed without special tools. It is strictly forbidden to use pliers to repair the device, since they can strip the threads, as a result of which it will be necessary to change the entire valve. In the absence of a wrench or adjustable wrench, it is better not to start repair work at all.
There are many different models of water valves on the market today. Due to the variety of choices, you can easily choose a design that meets all the requirements and desires of the buyer.
Correct mounting position
Equipping various types of valves with standard steel flanges ensures simple installation operations. Flanged connections allow you to quickly replace faulty shut-off valves without the need for complex preparatory operations. Replacement of fittings equipped with flanges is carried out without dismantling adjacent sections and carrying out welding operations. To seal the joints tightened by steel studs and nuts, gaskets of the appropriate configuration are used, placed between matching flanges of identical size.
When installing valves, it is not necessary to take into account the direction of flow of the working medium. In valves, the working medium can be transported in both directions.
Fig. 3 Standard sizes of valves
When installing valves, any orientation of the device is allowed regardless of the flow of the working medium. The design of the shut-off element of wedge and parallel gates ensures guaranteed operability of the equipment in any direction of flow of the transported liquid or gaseous medium.
