If there is a leak in the gasket on a duplex strainer, what could be drawn into the fuel lines?

A leak in the gasket of a duplex strainer can allow air to be drawn into the fuel lines, which is a significant concern in boiler operations. The presence of air in the fuel lines can result in insufficient fuel being delivered to the combustion process, leading to improper combustion, potential burner damage, and system inefficiency.

When the integrity of the strainer's gasket fails, it disrupts the seal that is meant to keep the fuel system airtight. This not only allows the potential for air to enter but also compromises the function of the strainer, which is designed to filter out particulates and contaminants that could harm the fuel system.

While contaminants, moisture, and fuel might also pose issues within the context of system operation, they do not directly relate to the immediate consequence of a gasket leak in a duplex strainer as air does. Contaminants and moisture are typically what the strainer is meant to filter out, and fuel leaking from the system indicates a different type of malfunction. Therefore, air is the most relevant and direct concern in this scenario.