A return line from a burner or pump back to a supply tank shall have no valves or obstructions except for what?

In the context of oil fuel systems, the return line plays a critical role in ensuring the safe and efficient operation of burners and pumps. It is essential for preventing backpressure and allowing fuel to flow freely back to the supply tank. Having no valves or obstructions in this return line is crucial to maintain optimal performance and safety.

A hard seat valve or ball valve with the handle removed serves a specific function. This type of valve, when installed in the return line, can prevent backflow in certain scenarios while not being operable due to the absence of a handle. This ensures that under normal circumstances, fuel can flow back to the tank without interruption, and it provides a barrier to backflow in case of malfunction or pressure changes in the system.

By using such a valve, you ensure that it can only function as a one-way check, allowing return flow while minimizing the risk of obstructions or manual manipulation that could disrupt the system. Hence, this choice aligns with safety standards and operational efficiency required by the Maine Journeyman Oil Fuel Board Rules.