What effect does a blown diaphragm in the fuel oil characterizing relay have on the fuel oil header pressure?

A blown diaphragm in the fuel oil characterizing relay causes the system to lose its ability to regulate fuel oil flow properly. This malfunction can lead to excessive fuel being supplied to the combustion process. When too much fuel enters the system without corresponding adjustments to the air supply or combustion processes, it results in incomplete combustion, which can create a rich fuel mixture.

As a result, the pressure in the fuel oil system can surge, leading to conditions where the fuel ignites improperly, generating black smoke as a byproduct of this incomplete combustion. The presence of black smoke indicates that the fuel is not burning correctly, and the potential for pressure to reach maximum levels is a significant risk, leading to operational issues and possible damage to the system.

Understanding this relationship highlights the importance of the diaphragm's role in maintaining system stability and preventing excessive fuel delivery that can adversely affect combustion efficiency and fuel oil header pressure.