🔍 Key Concepts

• how fuel oil viscosity and density change with temperature • what the fuel oil service system (suction side vs discharge side) looks like • effects of overheating fuel on pump performance and burner sealing surfaces

💭 Think About

• Think about what happens to fuel oil if you keep heating it past the recommended temperature—does it get thicker or thinner, and how does that affect pumps? • Which of these problems is most directly connected to changes in viscosity and possible vapor formation in the fuel line? • Which part of the fuel system is most sensitive to fuel that is too thin or starting to form vapor: the suction line, the burner tips, or the heater surfaces?

✅ Before You Answer

• Check which option is most clearly related to viscosity becoming too low or vapor bubbles forming in the fuel oil • Confirm in your notes what happens to pump suction when the fuel starts to vaporize in the suction line • Eliminate options that mainly describe problems caused by too much fuel flow/heat to the boiler rather than properties of the fuel itself