Butterfly valve

butterfly valve may include a pressure-tight resilient seat and an angularly offset disc. butterfly valve designs use a hard seat and an O-ring or piston ring around the disk to seal.

Butterfly valves range in size from small to enormous, and are well suited for large flows of gases, liquids, or slurries, offer a number of advantages when used for the proper application. They may be used in a wide variety of chemical services, they are available with small dimensions allowing for use in areas where space is limited, and they allow a high coefficient of flow.

Conversely, the design of butterfly valve creates the disadvantage of not being easy to clean, and therefore should be avoided in situations that call for sterile, medical or food processing applications.

Additionally, some styles may have difficulty dispensing slurries.

Plug Valve

Plug valves, 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.
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 valves 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.