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Steam accumulator

A Steam accumulator is an insulated steel pressure tank containing hot water and steam under pressure. It is a type of energy storage device which is used to smooth out peaks and troughs in demand for steam in a factory.



The tank is about half-filled with cold water and steam is blown in from a boiler via a perforated pipe near the bottom of the drum. Some of the steam condenses and heats the water. The remainder fills the space above the water level. When the accumulator is fully charged the condensed steam will have raised the water level in the drum to about three-quarters full and the temperature and pressure will also have risen.


Steam can be drawn off as required, either for driving a steam turbine or for process purposes (e.g. in chemical engineering), by opening a steam valve on top of the drum. The pressure in the drum will fall but the reduced pressure causes more water to boil and the accumulator can go on supplying steam (at gradually reducing pressure and temperature) for some time before it has to be re-charged.

Pressure and temperature

This steam table shows the relationship between pressure and temperature in a boiler or steam accumulator:

Gauge pressure, PSI Absolute pressure, PSI Temperature, °C Temperature, °F
0 15 100 212
35 50 138 281
85 100 164 328
135 150 181 358
185 200 194 382
235 250 205 401

Abbreviations and notes

See also

  • Fireless locomotive


  • Everyman's Encyclopaedia 1931, volume 2, page 543
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Steam_accumulator". A list of authors is available in Wikipedia.
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