A valve is a device that can be used to control the flow of liquids, gases, and slurries. Also known as regulators, valves can be found in almost any situation. They are also made in a number of different designs, depending on how they are being used, and they can be found in a range of sizes from smaller than a pinky to gigantic. Valves also vary from the extremely basic to the extraordinarily complex. They are one of the oldest mechanical designs, and basic ones have been in use for thousands of years.
The term “valve” can be used to refer to human anatomy as well as a mechanical device. Those found throughout the body regulate the flow of blood, oxygen, and body fluids. They include the extremely important heart valves, which work with the heart to pump blood through the body. Individuals with damage to those in the heart may have them replaced with artificial ones to perform this vital body function. The many valves in the human body work together to keep things running smoothly in a person's daily life.
Many permutations of the mechanical variety exist, but the following are common ones that most people probably see and use on a daily basis. The most basic is the gate valve, which has two positions: open, and closed. A globe valve is slightly more complex, controlling not only the flow of liquid, but also the amount, and is also called a throttle. For example, most taps are this form, allowing users to turn the water on and determine how much water is going to flow out. Manufacturers also make check valves, designed to restrict the flow of a substance to one direction only, and safety valves, which can release dangerous levels of pressure.
This device can be manually controlled, like a tap, or controlled by a large system, as is the case in a car, where they open and close to permit combustible fuel to enter the cylinder. In the case of a safety valve, it may be set to trigger when a certain pressure level is reached, or when an emergency signal is sent out. Usually, such devices are equipped with small springs that will hold them shut until they needs to be opened. In other instances, they may be controlled by users through a computer system, as is the case with oil, gas, and water pipelines that sprawl for miles; technicians in a central control center can open and close valves remotely, as needed.