More about Valves

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Valves control the rate of flowing media which is permitted to travel from one location to another in a mechanical device. Usually, valves have two ports called inlets and outlets, a seal that is used to control the flowing media, and an orifice or seat.

The force that causes the valve to function, actuation, can be either manual or automatic. Manual valves use the simplest form of actuation. An external force is necessary for the valve to function properly. Automatic valves, also called self-actuating valves, operate free from any external source. Actuated valves require an external mechanic device to function.

The majority of valves have a default position of closed, requiring some form of external intervention to function properly. Fail-safe valves will automatically return to the default closed position when the external force is removed.

Some valves have a default position of open. These valves remain open continuously unless closed, usually for maintenance or repairs. These fail-safe/open valves are most often found in cooling systems where constant flow is required.

Throttling valves are used to control the amount of flowing media through the valve. Throttling valves use the amount of external pressure applied to control the rate at which the flowing media passes through the valve. A kitchen sink spray head is a good example of a simple throttling valve. The more pressure applied to the trigger of the spray head, the stronger the flow released from the valve.

Valves come in various materials to meet individual requirements. These materials include plastic, carbon and stainless steel, ductile or cast iron, brass, and bronze. Each available material offers certain benefits to the individual valve. Certain valves can only be formed from a specific material due to environmental conditions the valve must function under.

Common types of valves include gate valves, butterfly valves, globe valves, ball valves, relief valves, safety valves, and check valves. Each valve has distinct advantages, as well as disadvantages. Quality depends mostly on the material used in creation of the valve and the final price of the valve itself. Inexpensive plastic valves are often created using molds and cheap plastic. Expensive valves are most often made by special molds and carbon steel. As you can see, the more expensive the product, the longer the life of the valve.

Valves may not always be seen, but they are an important part of making our lives easier. While we may not think about the importance of a good valve, many of the mechanical devices we use on a daily basis function more smoothly because somewhere, a good valve is doing its job.