Where is the automatic non-return valve located on a high pressure boiler?

The automatic non-return valve, also known as a check valve, is primarily located at the outlet closest to the boiler. This positioning ensures that water or steam generated in the boiler can exit but prevents backflow into the boiler from the system, which is vital for maintaining safe and efficient operation.

In high-pressure boilers, you want to ensure that once the steam or heated water has exited the system, it does not flow back into the boiler. Placing the valve at the outlet allows it to prevent reverse flow effectively, safeguarding the boiler from potential damage that could arise from unwanted backpressure or flow reversal.

The other locations mentioned may have their own specific functions in a piping system, but they do not provide the same level of protection against backflow in the critical area right where steam or heated water exits the boiler. Each system may have unique designs, and understanding the role of such valves in relation to the boiler's operational safety is essential for a journeyman pipefitter.