Boiler water level alarms

The function of high and low level alarms. Low-level alarms will draw attention to low boiler water level and, if required, shut down the boiler. High-level alarms protect plant and processes.

Where boilers are operated without constant supervision (which includes the majority of industrial boilers) low water level alarms are required to shut down the boiler in the event of a lack of water in the boiler. Low level may be caused by:

A feedwater shortage in the feedtank.

Failure of a feedpump.

Accidental isolation of the feedwater line

Failure of the level control system.

The regulations covering boilers have built up over the years in response to boiler explosions, damage and loss of life. Whilst boiler explosions are now very rare, damage to boilers which is attributable to low water level still occurs.

The effect of low water level in a boiler is that the heated tubes or the furnace tube(s) become uncovered and are no longer cooled by the boiler water. The metal temperature rapidly increases, its strength is reduced and collapse or rupture follows.