What is the usual oil pressure at the nozzle in a high-pressure gun type oil burner?

• A. 50 psig
• B. 10 psig
• C. 100 psig
• D. 300 psig

Answer: (C)

The key idea is that the nozzle must be pressurized enough to atomize the fuel oil into a fine spray for efficient combustion. In a high‑pressure gun type oil burner, about 100 psi at the nozzle provides the right balance: it produces a good spray pattern and proper droplet size for reliable ignition and efficient burning. Pressures around 50 psi are typically too low for proper atomization, which leads to incomplete combustion and poor flame quality. Very high pressures, like 300 psi, aren’t standard for this type of burner and can strain components and alter spray characteristics in undesirable ways. Ten psi is far too low to overcome the nozzle orifice and achieve atomization.