A guardian valve is a
valve
A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fittings ...
used in
marine
Marine is an adjective meaning of or pertaining to the sea or ocean.
Marine or marines may refer to:
Ocean
* Maritime (disambiguation)
* Marine art
* Marine biology
* Marine debris
* Marine habitats
* Marine life
* Marine pollution
Military
* ...
steam turbine
A steam turbine is a machine that extracts thermal energy from pressurized steam and uses it to do mechanical work on a rotating output shaft. Its modern manifestation was invented by Charles Parsons in 1884. Fabrication of a modern steam turbin ...
propulsion plants to prevent steam from leaking into the
astern turbine while the vessel is operating in the ahead mode. It is normally installed between the astern
throttle valve and the astern elements of the low pressure (LP) turbine. Typically only the LP turbine of a steam ship's propulsion plant has reversing blade elements. Steam leaking in such a manner would result in a loss of efficiency and possibly overheat and damage the turbine blades.
The guardian valve must be opened prior to any
maneuvering situation, in order to permit the astern turbine to be used to bring the vessel to a rapid stop or to back down.
Any similar arrangement of a stop valve used to protect leaking past a throttling valve could also be referred to as a guardian valve.
References
Safety valves
Marine steam engines
Steam turbines
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