Flash boiler

A flash boiler differs from the type of monotube steam generator in which the tube is permanently filled with water.

Serpollet's boiler was a low-water-content type with thick-walled tubes to provide a store of heat.

Flash boilers are lighter and less bulky than other types and take less time to raise steam from a cold start.

However, they are more prone to overheating because there is no large reservoir to cool the tubes if the water flow is interrupted or inadequate.

Flash boilers are normally fired by liquid or gaseous fuel because this allows a quick response to changes in the demand for steam.