What does a water valve consist of?

The device of the water supply system is not complete without a shut-off valve. It completely shuts off the water supply to the system or one of its points, or limits the pressure. In private construction (for an apartment or a cottage), water taps and valves for plastic pipes are mainly used. The metal system also has its own components.

Types of water valves and their device

A water valve is a special shut-off valve that is installed at the inlet of the system to one or more plumbing points. With the help of a tap, you can limit the water supply to only one device (toilet, sink, washing machine) or throughout the entire riser at once. It all depends on where the fittings are installed.

Locking mechanisms are classified into several categories depending on the principle of operation, design, material of manufacture, throughput and method of attachment to the pipe.

According to the principle of operation, there are two types of valves: ball and valve. The first one works due to a special locking mechanism in the form of a ball inside, which has a special hole. At the moment of turning the lever / valve, the sphere turns in such a way that the gap is perpendicular to the flow of water in the pipe. Its delivery stops. This is clearly seen in all assembly drawings for valves. The positive aspects of the ball valve are the complete tightness of the closed pipe, the simplicity of the mechanism and the long service life. This type of water valve cannot be repaired. The most durable of this class is considered to be a mechanism made of brass "Zubr" on a ¾ ”pipe.

The valve assembly consists of a gasket that is mounted on the stem. At the moment of turning the valve, it partially or completely blocks the flow of water, depending on the position of the shut-off valve. Important positive aspects of the valve device are its maintainability and the ability to control the water pressure in the system. The disadvantages include the rapid wear of the gasket and the need to make several turns with the flywheel until the water is completely blocked.

If there is a need to completely shut off the water, it is better to install a ball valve. If the head needs to be adjusted, a valve valve is the right solution.

By design, shut-off valves are divided into three types:

• Direct-flow. A crane with a low hydraulic resistance, which is installed on a straight section of the system.
• Checkpoint. Designed to block the flow of water in a specific direction.
• Corner. It is used at the corner joint of pipes. In this case, the water flow is perpendicular to the incoming direction.

According to the material of manufacture, cranes are:

• Steel. They are used more often for cold water, since scale deposits on it from hot water. Old-style water valve taps were made of steel.
• Brass. They are lightweight and lightweight. Durable and suitable for cold and hot water installation.
• Bronze. The most expensive version of the locking mechanism with excellent performance.
• Plastic. Unpretentious, durable, affordable devices.

Valve mounting methods:

• Flanged. They are mounted with special fasteners along the edges of fittings and pipes. Bolted. Such shut-off valves are installed only on a metal water supply system.
• Threaded. Mounted with a lock nut for locking and threading. Such a crane is selected according to its diameter, pitch and type of thread (internal / external).The threaded valve can be installed on plastic and metal pipes. In the case of plastic, special adapters are used.
• Welded. They are installed only by welding.

Only screw and flanged valves can be removed and replaced. The welded one is not re-installable.

In terms of throughput, mechanisms are:

• Full bore. Allows almost 100% of the water flow to pass through.
• Standard. They work with 70-80% of the fluid pressure in the system.
• Incomplete bores. Only 40% to 50% of the flow is allowed through.

There are special three-way taps that allow you to connect a pressure gauge and monitor the operation of the water supply system.

The main criteria for choosing a shut-off valve

Choosing a valve at a specialized point of sale, the master pays attention to the following parameters:

• Mechanism type (ball, valve).
• Manufacturing material. For metal systems, take brass or bronze valves. For polymer - plastic.
• Mounting method.
• Bandwidth.

When choosing a crane by the type of fastening, it is necessary to take into account whether the valve will be mounted once and for a long time, or in the future it will be dismantled and reinstalled.

Valve mounting methods

Depending on the method of fastening, the installation of shut-off valves is carried out according to different schemes. The threaded locking mechanism is mounted in the following order:

1. The pipe is being prepared for the installation of fittings. Threads must be cut at both ends, if there is none. For this, a die of the required diameter is used. It is rotated along the pipe until a thread is formed. For more convenience, you can use a die holder.
2. Locknuts are put on both ends of the prepared pipes. They will further fix the valve. When installing all threaded connections, it is advisable to use FUM tape or other sealant.
3. Screw on the tap and clamp it on both sides with locknuts.

Threaded mechanisms are mounted on pipelines with a cross section of 10 to 60 mm. The working pressure in this case can vary within tens of atmospheres (a special high pressure valve is selected). The body type can be either angular or straight-through.

The flanged valve is installed according to the following scheme:

1. Flanges are welded onto the pipes, which are then combined with the washer of the mounted crane.
2. A sealing gasket must be installed between the washers.
3. The fastening bolts are inserted into the technical holes of the washer. They are tightened in parallel at the time of valve installation. You need to do three to four turns for each fastener. No longer needed, otherwise there is a risk of stripping the thread or damaging the pipe.

Flanged valves are installed on pipelines with a cross section from 10 to 160 mm. All flanges must comply with GOST 12820-80, about which there is a corresponding marking on the valve body. It is permissible to install both angle and direct-flow cranes of this type.

Operation and maintenance

In order for the crane to work without interruptions, it is recommended to handle it correctly:

• do not jerk sharply at the moment the water is cut off;
• do not squeeze over the stop;
• the ball mechanism must be left only in one of the positions (open / closed), otherwise it quickly fails;
• periodically lubricate old-style metal valves.

If valve fittings are used, it is advisable to install a special filter at the inlet to the system. This will protect the gasket (valve) from excessive wear.