In our daily life, we must be familiar with the valve.
In fact, it is not uncommon for us to find valves in everyday life, for example the water faucet at home when we brush our teeth and on the toilet flush.
But, do you know more about what valve is?
In this article, we will learn more about valves.
A valve is a mechanical device that controls the flow (fluid) and pressure in a system or process by opening, closing, reducing or increasing the flow. They are important components of piping systems carrying liquids, gases, steam, slurries, etc.
For example, when you turn on the faucet to brush your teeth, you open the faucet allowing pressurized water to exit the pipe. Similarly, when you flush the toilet, you open two valves: one (the siphon) which allows water to escape to empty the pot and the other (called the ball valve or ballcock) which puts more water into the tank ready for the next flushing.
There is also an open valve, the water flow is regulated from high pressure to low pressure, this will make the fluid flow process easier and more flexible.
Main Functions of Valve
In this section, we will know the functions in general. The following is the function of the valve:
- Stops and starts the stream.
- Reduce and increase flow.
- Control the flow direction.
- Regulate process flow pressure.
- Lighten the pipe system with a certain pressure.
There are many designs, types and models, with various industrial applications. All fulfill one or more of the functions identified above. Valves are expensive items, and it is important that the correct valve is specified for its function, and must be made of the correct material for the process fluid.
Regardless of the type, all valves have the following basic parts: body, bonnet, trim (internal elements), actuator and packing. The base of the valve is illustrated in the figure to the right.
In this section we will study the parts of the valve:
The valve body, sometimes called the casing, is the main limiting pressure valve. It serves as the main element of the valve assembly because it is the framework that holds all the parts together.
The cover for the opening in the body is the bonnet (hood), and this is the second most important boundary of the pressure valve. Like valve bodies, hoods are available in many designs and models.
Bonnet serves as a cover on the valve body, made of the same material as the valve body. These are usually connected to the body by threaded, bolted, or welded connections. During valve manufacturing, internal components, such as stems, disks, etc., are inserted into the body and then bonnets are installed to hold all the parts inside.
TRIM VALVE: REMOVABLE AND REPLACABLE INTERNAL PARTS of the VALVE that come into contact with the flow medium collectively. These parts include valve seats, discs, glands, spacers, guides, bushings, and internal springs. Valve body, bonnet, packing, etc. Those also in contact with the flow medium are not considered valve trim.
The performance of the trim valve is determined by the disc and seat interface and the disc-to-seat position relation. Due to the trim, basic movement and flow control is possible.
The disc is the part that allows, throttles, or stops flow, depending on its position. In the case of a plug or ball valve, the disc is called a plug or ball.
The disc is the third most important primary pressure limit. With the valve closed, full system pressure is applied across the disc, and for this reason, the disc is a pressure related component.
The seat or seal ring provides a seating surface for the disc. Valves may have one or more seats.
The stem provides the necessary movement to the disc, plug or ball to open or close the valve, and is responsible for the correct position of the disc. It is connected to the valve handwheel, actuator, or lever at one end and to the valve disc on the other.