What is the function of a Flash Tank in a Boiler ?

The Flash tank is used to flash the condensate at high temperature into steam. The primary function of the Flash Tank is to reduce the pressure of the condensate.  Some of the condensate "flashes" into steam in the Flash Tank.This low pressure condensate can be reintroduced into the boiler or condensate through the low pressure lines.  The steam can be used in place of live steam in the boiler system.

The Flash Tank serves to preserve the heat content of the condensate while reducing the pressure to a safe value.  The Flash Tank is a very important component of closed systems.  In fact, the flash tank is what makes closed systems possible