What is a Valve?

Mary McMahon
Mary McMahon

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.

A gate is lifted into or lowered from a neck area to control flow in a gate valve.
A gate is lifted into or lowered from a neck area to control flow in a gate valve.

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.

Ball valves control the flow of a gas or liquid by rotating a spherical surface inside the pipe.
Ball valves control the flow of a gas or liquid by rotating a spherical surface inside the pipe.

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.

Human heart valves open and contract to control blood flow.
Human heart valves open and contract to control blood flow.

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.

Ball valves can be used to adjust the amount of gas or liquid that is flowing in a system.
Ball valves can be used to adjust the amount of gas or liquid that is flowing in a system.
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments

anon229861

Are there valves which allow you to split flow into two or more branches?

gremlins

So this may be kind of a silly question, but since there are so many ways to keep mechanical valves running properly -- lubrication, regular check-ups on the mechanics, etc, are there things that you can do to keep the valves in your body working properly as well?

I mean, you obviously can't go in and physically check up on an anatomical valve, but are there certain foods or exercises that can help keep your valves going strong?

moonTiger

Another place you'll find valves is on certain musical instruments, such as the trumpet or the trombone, or even the French horn. Call me a music nerd, but it's actually really interesting to look at the different kinds of valves on instruments.

For instance, trombones have a rotary valve which directs the airflow into lengths of tubing when they're rotated 90 degrees. Another type of valve found on trombones is the Axial flow valve, which has begun replacing the previously-mentioned rotary valve. There's also a valve called the Stolzel valve which was used on the French horn. However it has been replaced by the double-piston valve, where two pistons are moved simultaneously and bend the air flow in two right angles to introduce an additional valve loop.

anon15438

on a 2007 Chevrolet cobalt, is the head not tap drew cylinder valve or it is drew in??

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