What safety feature is required for every steam boiler not under continuous supervision?

Every steam boiler not under continuous supervision is required to have a low water cut-off as a crucial safety feature. This device is essential because it automatically shuts off the fuel supply to the burner when the water level in the boiler drops below a safe level. If water levels are too low, it can lead to overheating and potentially catastrophic failure due to dry firing, where the boiler operates without sufficient water to absorb the heat, leading to damage to the boiler and posing significant safety hazards.

In systems that are not under constant supervision, the risk of operator oversight or failure to notice a drop in water level increases. Hence, the low water cut-off serves as an automated safety mechanism, ensuring that the boiler operates safely even in the absence of constant human oversight. The presence of this device thus provides an essential layer of protection in the operation of steam boilers.

While other features like pressure regulators, emergency shut-off valves, and feedwater flow meters have their roles in boiler operation and safety, they do not specifically address the immediate danger associated with low water levels, making the low water cut-off particularly critical for unattended boilers.