What does the term "low-pressure boiler" generally refer to?

The term "low-pressure boiler" is generally defined as a boiler that operates at pressures below 15 psi. This classification is important because it dictates the design, safety regulations, and operational procedures that must be followed when using such equipment. Low-pressure boilers are commonly utilized in heating applications, such as in residential settings or smaller commercial buildings, where high steam generation or higher pressures are not necessary for the intended purpose.

Understanding this classification is crucial for those working with and maintaining boiler systems, as it affects factors like pump selections, fittings, and safety devices. By highlighting the specific pressure threshold of less than 15 psi, option B accurately captures the essence of what qualifies a boiler as low-pressure.