What is a Valve?

The valve of the Roman plug The Romans invented the first valves about 2,000 years ago. They were utilized in plumbing systems in homes. The name of the valve builder was not stamped on the valve or the piping components, which is an interesting piece of information. If it was the owner of the house where the pimping was done, a name was stamped on the valves. Early Roman valve and piping designs were employed in a wide range of water supply applications.

These basic Alloy 20 Valves designs would not change significantly over the next 2,000 years. The Dark Ages stifled the development of flow control technology, as they did other scientific advances, and it wasn’t until the emergence of the steam-powered Industrial Revolution that valve designs began to adapt and improve.

Manufacturers were constrained by the physical parameters of the ball’s diameter and had to maintain a sufficient wall thickness to resist pressure within the valve’s body. The ball’s interior diameter could not exceed the machined bar’s inside diameter. In addition, the size of the ball orifice (the opening in the ball through which the media flows) was limited due to the requirement of maintaining a minimum wall thickness.

Functions of Valve Include on/off Service

Isolating Valves

Isolating valves, also known as block valves, are used in on/off service. They are meant to turn lights on and off in either a completely open or fully closed state, just like light switches. These valves are frequently motor-operated in important applications. The gate valve is the most frequent type of isolating valve, but other types have improved significantly in recent years.

Regulating and Controlling

Control valves are used to manage the flow of a line and come in a variety of shapes and sizes. They’re made to work in a “less-than-full-open” position. A globe is the oldest and most popular regulating valve design. Unless the flow velocity is extremely low, gate valves should never be utilized for throttling or regulating. When a gate valve is used for regulating, high-velocity flow can quickly erode the seating surfaces and cause leakage when fully closed. The flow rate should be proportionate to the amount of stem closure for appropriate flow regulation. Certain control applications, such as those requiring a quick opening reaction, may not need to meet such standards.

Non-return or Check

Examine the valve design as illustrated in the diagram on the left, check and non-return valves only allow flow in one direction. And prevent it from returning in the opposite direction. Check valves are the valve industry’s “one-way-street controllers.” They are marked on the outside with a flow arrow to ensure that they are put in the correct orientation. Many pieces of industrial equipment, such as pumps, turbines, and boilers, are protected by check valves. These valves will lead to some extent unless they are supplied with soft, elastomer seating inserts. Check valves should not be relied on for absolute shut-off unless they are soft-seated.