The automatic non-return valve on a high pressure boiler is located ________________ .

The automatic non-return valve on a high pressure boiler is typically found at the boiler proper outlet. This location is crucial because it prevents the backflow of steam or water from the system back into the boiler when the boiler is not in operation or during a fault condition. The valve ensures that once steam is produced and sent out from the boiler, it cannot return, which maintains the integrity of the system and safety for the operation.

In a correctly functioning high-pressure boiler system, the valve's placement is designed to ensure efficient operation and safety, preventing scenarios that could lead to water hammer or other issues that occur due to backflow. Additionally, having it at the outlet allows for clear and unimpeded steam flow to the intended applications, whether they are heating systems or other industrial processes.

The other locations, such as the main steam header or feedwater intake, do not serve the same critical function as the outlet position. The main steam header typically serves to distribute steam to various system components, while the feedwater intake is where water enters the boiler, and a non-return valve there would not effectively serve high-pressure application needs. Similarly, placing the valve near the blow-off valve would not adequately address the backflow concerns at the point where steam exits the boiler