Plug valve

Plug valve also called cock or stop-cock valves, date back to ancient times, where they were developed for use in citywide Roman plumbing systems. Today, they remain one of the most widely used valves for both on/off and throttling services. Their design is fairly simple; the body is comprised of three main parts: body, cover and plug. The plug is a cylindrical, tapered, or generally cone-shaped device that can be raised or lowered within the seat to maintain, restrict or completely shut off flow. The valve is opened by rotation, with the plug itself being the only element that is capable of movement. Early models of plug valves used metal-to-metal seals that were nonlubricated. This design is still used, but problems with galling and sticking limit their usefulness. The use of lubricant between the plug face and the seat eliminates most of these problems. The lubricant helps to control leakage around the plug, reduces wear between the valve contact surfaces, and slightly lifts the plug to reduce the operating torque required to operate the valve.

Ball valve

Ball valve are the three different types of rotary valves used in industrial plants. They are widely used in fluid-handling systems for flow control. These types of rotary valves are suitable for corrosive applications. They are used in detergent, pharmaceutical, chemical, rubber, pulp and paper plants, water treatment systems, textile mills and food processing plants, In general, ball valves offer many advantages when contrasted with other valve types. They provide superior ease of operation and can maintain and regulate high volume, high pressure and high temperature flow. Most ball valves offer rugged construction providing for a long service life, and a comparably low cost. Additionally, the design of the regulating element allows the valve to function without the complications of side loads, typical of butterfly or globe valves, and the valve design permits inspection and repair of seats and seals without removing the valves’ body from the line.

Gate valve

Gate valve are advantageous in applications involving slurries, as their “gates” can cut right through the slurry. They are also used in applications that involve viscous liquids such as heavy oils, light grease, varnish, molasses, honey, cream and other non-flammable viscous liquids. They are available in large sizes to better handle thick flow. However, Gate Valves do have low-pressure limitations, and are not optimal in applications that require cleanliness or sanitary conditions. They are excellent for use anywhere a shutoff valve is needed. They can also be used where throttling capabilities are desired, although this is not generally recommended as erosion of the seat and disc occurs due to the vibrations of the disk in throttling applications.