Electrostatic precipitators are used to separate small particles, 1 micron or smaller, from gas streams. This process is also used in desalters to separate salts and sediment from crude oil feeds.
Cyclones are used mainly to separate solids from liquid or gas streams. The hydrocyclone shown below is used to clean coal.
In centrifuges, a centrifugal force, generated by high speed rotations, is used to separate solids from liquids. Centrifugation can be used to recover solids from slurries, to clarify liquids, or to clarify solids.
Compressors are used to increase the pressure of a fluid. The main type of compressor is the rotary compressor, meaning a rotary device is used to compress the fluid. Reciprocating and centrifugal compressors are the most common.
Chlorinators supply chlorine as a high pressure liquefied gas to disinfect a water supply.
Aerators and diffusers are used to increase the gas content of a liquid, typically oxygen in water. Diffusers are a specific type of aerator in which air is diffused through a surface and into the liquid itself. The name does not refer to the process of diffusion through the liquid.
Actuators are used to open and close valves. Pneumatic actuators use pressurized air for control. Electric actuators use electrical power (e.g. an electrical motor).