A steam separator, sometimes referred to as a moisture separator, is a device for separating water droplets from steam. The simplest type of steam separator is the steam dome on a steam locomotive. Stationary boilers and nuclear reactors may have more complex devices which impart a "spin" to the steam so that water droplets are thrown outwards by centrifugal force and collected. All separators require steam traps to collect the water droplets that they remove.
It is important to remove water droplets from steam because:
- In all engines, wet steam reduces the thermal efficiency
- In piston engines, water can accumulate in the cylinders and cause a hydraulic lock which will damage the engine
- In thermal power stations, water droplets in high velocity steam coming from nozzles (or vanes) in a steam turbine can impinge on and erode turbine internals such as turbine blades.
- In other steam-using industrial machinery, water can accumulates in piping and cause water hammer
- Rubber vulcanizing machines
- Steam-powered irons
- Cooking processes using a steamer
- Catalyzing systems
- Other steam system