Boiler Bottom Blowdown Sequence
Below is a typical example of Boiler Bottom Interlocking, although variations occur between sequences. Designs can be produced to suit all boiler configurations.
In the sequence shown, the three individual boilers have their own blow-down line into a single blow-down vessel.
The blow-down line incorporates two isolating valves. These valves are equipped with mechanical (manually operated) valve interlock devices. These locks are set to release the key (and lock the valve) in the closed position.
As each of the isolating valve interlocks share the same key, and only one key is in circulation, only one valve can be opened at a time.