Shut-off and control valves are used to change the flow rate of the transported media to a complete stop . Water tap for water has the following properties:
- simplicity of design and operation;
- application at large pressure drops;
- small size and weight;
- the ability to install on any section of the pipeline;
- Slight shutter speed provides convenient maintenance.
Valve Types
Shut-off and control valves are classified according to three criteria:
- body shape;
- type of locking part;
- installation method in the system.
According to the shape of the body, the valves are as follows:
- direct-flow - the flow is blocked by the valve seat in the transverse direction;
- angular - the locking element moves towards the movement of the medium;
- mixing - to obtain a given water temperature.
The locking element varies in design:
- Ball - a through sphere in a direct-flow housing. When combining the longitudinal axes of the hole and the body, the flow movement fully opens. A rotation in the perpendicular direction by 100% blocks the flow of fluid. The valve functions only as a shut-off element, but it is not suitable for regulation. The use of the device is associated with its high reliability, speed of flow shutoff and compactness. It practically does not break anything, since there are very few details.
- Valve - with a lock associated with a threaded rod screwed into the seat nut. The unit is used to control the flow rate and to completely block the flow (in the lowest position).
- Needle - conical piston with regulation of fluid flow under high pressure (about 220 bar).
Valve Materials:
- ball: brass, stainless or structural steel ;
- valve: cast iron, brass.
New materials are also used for the manufacture of valves. The polypropylene housing makes the device durable and at the same time cheap. Fluoroplastic coatings can increase resistance to corrosion and aggressive environment.
The difference between valve and tap
Water taps and valves vary, although they are often identified. The latter is installed between the joints of two pipes, forming a line. The faucet includes a valve and a spout directly through which water flows out.
The device and operation of the valve valve
The most important valve working element is a saddle with a shutter manually moved by the spindle. The water valve, the device of which is shown below, contains a thread in the body and on the stem, which has the property of braking. As a result, the shutter disk is pressed firmly against the seat, blocking the flow when the valve is closed. In the open state, the flow area remains unchanged when the water flow moves.
Typically, the thread is not made in the housing because it wears out quickly. To do this, a running nut is attached to it, into which a spindle is screwed. Then, instead of a worn-out unit, you can install another, but the case will be preserved. All parts are interchangeable with a water tap (GOST 12.2.063-81, GOST 5761-74).
The valve opens by turning the knob. In this case, the spindle translates, freeing the passage for fluid. If rotation is reversed, the valve closes.
The device is connected to the pipeline through the inlet and outlet pipes. Between them they can be distinguished by the presence of an arrow indicating the direction of flow.
Angle valves
For a perpendicular change in the direction of fluid transfer with overlapping and adjustment capabilities, an angled water valve is used (drawing below: a - through passage; b - angular).
The perpendicular arrangement of the inlet and outlet nozzles determines the purpose of the valve for pipelines that change direction by 90 ° . The principle of his work is the same as that of the checkpoint. The shutter stroke is made coaxially with the inlet pipe.
Scope of corner gates:
- When the pipes are connected to the heating radiator, when it is blocked or the flow rate of the coolant is regulated, the water valve (see photo below). Models made of high-temperature polypropylene are more convenient and cheaper than brass when connected to plastic pipes.
- Prevention of vibration and swaying of pipelines.
- Decrease in fluid flow rate without high-frequency noise.
- In fire water pipelines during operation in any position.
- Simplification of pipe installation by reducing hardware consumption.
The device and principle of operation of the ball valve
The main working body of the valve is a ball with a through hole. When the handle is positioned along the pipe, the tap is open. If it is turned perpendicular to the pipe, it will close. The hole in the ball can be round, square, in the form of a trapezoid or oval. In small-diameter valves, the crane is made floating, and for large-sized devices it is made on special supports. High shutter tightness is ensured by an elastic seal. This allows you to install this type of model on gas pipelines.
The water ball valve works in two extreme positions when turned 90 ° when it is fully open or closed. Attempting to control the flow will lead to rapid wear of the seal.
Ball valves have wider possibilities for connecting pipes when installing water supply systems:
- walk-through;
- angular;
- with three or more bends in order to redirect transported flows.
Connections with pipes are made nipple, flanged and welded. The latter option allows you to permanently install a plumbing valve in the system.
Shower Mixer Taps
The device is single-ball or in the form of two valve valves. The kit includes a replaceable shower head with attached flexible hose and a spout in the bath. The mixer is performed hidden, bringing out only the temperature control valves of the water.
A classic option is a two-valve accessory with manual temperature adjustment. Cold and hot water are mixed in a special chamber, and then enter the shower hose or spout. The main elements of the device are two crane boxes with interchangeable gaskets.
The one-lever device with convenient adjustment of water becomes popular. The main element of the mixer is a replaceable cartridge. When a failure occurs, it is easily removed and replaced with a new one.
With integrated thermostat, adjustment is simplified. It is pre-configured, which guarantees the output of water with a given temperature. For this, a thermostatic element distributing flows is located in the housing. The only drawback of such models is the high price.
Mounting
Small diameter valves are mounted on threads (up to 60 mm). The pipe has a bend, the connection is sealed with hemp or fluoroplastic film. Winding is carried out in the direction of twisting of the thread. This creates a tight connection that can withstand high pressure.
A large-diameter pipe is connected by a flange to the washer of a straight-through or angle valve through a gasket. Pulling them together is done with bolts and nuts. The connection of the flange to the pipe is carried out by arc welding.
Water valve: repair
If the valve shutter element is damaged, it is replaced with a similar worn-out or new unit. For this, a section of the pipeline is freed from the liquid, blocking it on both sides. Then, the valve element is removed. The ball valve is removed completely with open-end wrenches or adjustable wrenches. On the flanges, the nuts are twisted in parallel and gradually - 3-4 turns on each.
First, check the condition of the seals, which are replaced when worn. Leaks occur mainly due to deformation of the gaskets and when the thread is broken if improperly installed. Then the body and saddle are inspected. If there are no cracks, the assembly is reassembled. The case cannot be repaired if mechanical damage appears on it. Attachment to the pipeline requires trimming and the need for further welding work.
In this case, you will have to install a new or renovated water tap. An untrained person should not undertake complex repairs because of ignorance of his features.
Shut-off valves create additional resistance, so blockages can form at the joints. Do not always remove valves. Sometimes it’s enough just to flush the pipelines, opening all the taps.
Gland replacement can be done carefully with your own hands. To do this, shut off the water supply from the riser, disassemble the locking mechanism, replace the gaskets and lubricate the moving parts.
Conclusion
The water tap is simple to operate and requires no special maintenance. Each model should be used for its intended purpose. Simple valve repair can be done with your own hands, if you act carefully and correctly.