Ball valve
Butterfly valve
Check valve
Choke valves
Diaphragm valve
Double check
Gate valve
Globe valve
Needle valve
Plug valves
Rotary valves
Relief valves

Choke valve :

Choke valve is valve that lifts a solid cylinder (called a "plug" or "stem") up and down which is placed around or inside another cylinder which has holes or slots. The design of a choke valve means fluids flowing through the cage are coming from all sides and that the streams of flow (through the holes or slots) collide with each other at the center of the cage cylinder, thereby dissipating the energy of the fluid through "flow impingement". The main advantage of choke valves is that they can be designed to be totally linear in their flow rate.

Heavy duty industrial choke valves control the flow to a certain Flow Coefficient (Cv) determined by how far the valve is opened. They are regularly used in the oil industry and for highly erosive and corrosive purposes, they are often made of tungsten carbide or inconel.

A choke valve is sometimes installed in the carburetor of internal combustion engines. Its purpose is to restrict the flow of air, thereby enriching the fuel-air mixture while starting the engine. Depending on engine design and application, the valve can be activated manually by the operator of the engine (via a lever or pull handle) or automatically by a temperature-sensitive mechanism.

Choke valves are important for carbureted gasoline engines because small droplets of gasoline do not evaporate well within a cold engine. By restricting the flow of air into the carburetor, the choke valve causes more vacuum inside the carburetor and hence a greater amount of fuel to be sucked into the engine compared to normal operation. Once the engine is warm (from combustion), opening the choke valve restores the carburetor to normal operation, supplying fuel and air in the correct stoichiometric ratio for clean, efficient combustion.

Chokes were nearly universal in automobiles until fuel injection replaced carburetion in the late 1980s. Choke valves are still extremely common in other internal-combustion applications, including most small portable engines, motorcycles, small prop-powered airplanes, and carbureted marine engines.

Applications Of Check Valves

Check valves are often used with some types of pumps. Piston-driven and diaphragm pumps such as metering pumps and pumps for chromatography commonly use inlet and outlet ball check valves. These valves often look like small cylinders attached to the pump head on the inlet and outlet lines. Many similar pump-like mechanisms for moving volumes of fluids around use check valves such as ball check valves.

Check valves are used in many fluid systems such as those in chemical, and power plants, and in many other industrial processes.

Check valves are also often used when multiple gases are mixed into one gas stream. A check valve is installed on each of the individual gas streams to prevent mixing of the gases in the original source. For example, if a fuel and an oxidizer are to be mixed, then check valves will normally be used on both the fuel and oxidizer sources to ensure that the original gas cylinders remain pure and therefore nonflammable.

Some types of irrigation sprinklers and drip irrigation emitters have small check valves built into them to keep the lines from draining when the system is shut off.