Gate Valves are Bi-directional Multi-Purpose Valves and are available in various materials of construction like Brass, Lead-Free Brass, Bronze, Cast Iron with Rising or Non-Rising Stem for use in Residential and Commercial Buildings. Typical services include; hot and cold water, HVAC, steam, compressed air, gas, and other general utility services. Gate valves are mainly designed to start or stop the flow, and when a straight-line flow of fluid and minimum flow restriction is needed. In service, these valves are mainly either fully open or fully closed. The disk of a gate valve is completely removed when the valve is fully open; the disk is fully drawn up into the valve bonnet. This leaves an opening for flow through the valve at the same inside diameter as the pipe system in which the valve is installed. These types of valves can be used for a wide range of liquids and provide a tight seal when closed.
Gate valves consist of three main parts: body, bonnet, and trim. The body is generally connected to other equipment by means of flanged, screwed or welded connections. The bonnet containing the moving parts is attached to the body, usually with bolts, to permit maintenance. The valve trim consists of the stem, the gate, the disc or wedge, and the seat rings. Gate valves are available with different disks or wedges. Ranging from the gate valves are usually made by the type of wedge used. Among them the most common one is –
Solid wedge is the most commonly used disk by its simplicity and strength. A valve with this type of wedge can be installed in each position and it is suitable for almost all liquids. The solid wedge is a single-piece solid construction and is practically for turbulent flow.
Flexible wedge is a one-piece disk with a cut around the perimeter to improve the ability to correct mistakes or changes in the angle between the seats. The reduction will vary in size, shape, and depth, a shallow, narrow cut gives little flexibility but retains strength. A deeper and wider cut or cast-in recess leaves little material in the middle, which allows more flexibility but compromises strength.
The split wedge is self-adjusting and self-aligning to both seat sides. This wedge type consists of two-piece construction which seats between the tapered seats in the valve body. This type of wedge is suitable for the treatment of non-condensing gases and liquids at normal temperatures, particularly corrosive liquids.