Valves The primary purpose of a valve is to direct the flow of fluids by starting, stopping, and throttling flow to make modern processing possible. Valves are designed to withstand pressure temperature, and flow, and can be found in homes and industry across the world. The most common valves found in the manufacturing industry are gate, globe, ball, check, butterfly, plug, needle, three-way, diaphragm, relief, angle, and multiport. All valves are selected for a specific purpose. Valves are classified by flow control elements, function, and operating conditions, such as pressure, flow, or temperature. The most common way to classify valves is by the valve s flow control element design. The flow control element is the part of the valve that controls the flow of fluid through the device. Most valves take their name from the type or des8igh of the flow control element. The body of the valve contains useful information referred to as bridge wall markings. This is specific information about the valve. One of the more common valves found in industry is a gate valve. A gate valve is typically operated in the wide-open, or completely shut position. This type of valve is used where flow rates are not restricted.
Globe valves are the second most common valve used I industry. A globe valve places a movable metal disc in the path of a process flow. This type of valve is most commonly used in the throttling service. Ball valves take their name from the ball-shaped, movable element in the center of the valve. The movable ball rotates to let flow pass through, and closes to stop it. Ball valves are not made for throttling service. Check valve is a type of automatic valve designed to control flow direction and prevent possible contamination or damage to equipment. The check valve prevents backflow as long as the device is operating properly. A common valve used for throttling and on-off service is a butterfly valve. The body of this type of valve is relatively small when compared with other valves, and occupies much less space in a pipeline. Butterfly valves are designed to be operated at low temperature and low pressure.