What operating condition requires two low water fuel cut-off devices in a steam boiler?

In steam boiler operations, unattended operation is a critical condition that necessitates the use of two low water fuel cut-off devices. This redundancy ensures that the boiler remains safe in scenarios where an operator is not present to monitor water levels actively.

Low water fuel cut-off devices play a vital role in preventing the boiler from running dry, which can cause significant damage or even catastrophic failure. With unattended operation, the risk of water level issues increases, as there is no immediate human oversight to address fluctuations in water levels.

By employing two cut-off devices, the system achieves a higher level of safety and reliability. If one device fails or malfunctions, the second device acts as a backup to ensure that the boiler will shut down safely before the water level becomes dangerously low. This dual protection feature is crucial for maintaining safety standards when the boiler is operated without constant supervision. In this context, the need for multiple safety devices becomes evident, as the consequences of low water conditions can be severe in an unattended setting.