Plant Operation Practice Test 2025 - Free Plant Operation Practice Questions and Study Guide.

Blow back in a boiler system refers to the sudden reversal of flow, particularly relating to gases within the combustion system. This phenomenon typically occurs when there is a drop in pressure, often due to a failure in the system's ability to maintain proper combustion conditions, or when the furnace pressure is less than the draft pressure of the boiler. Such a situation can generate a backflow of flue gases towards the burner or the furnace, which is characterized by a distinct drop in pressure.

In this context, knowing that blow back is associated with a reduction in pressure can help operators identify potential issues within their boiler systems, such as improperly functioning safety devices or inadequate ventilation, which needs to be addressed to ensure safe and efficient operation.