What is the effect of heating number 6 fuel oil before pumping?

Heating number 6 fuel oil before pumping primarily increases its flow rate. This effect is due to the reduction in viscosity that occurs when the oil is heated. Number 6 fuel oil, which is a heavy and viscous substance, can be difficult to pump at lower temperatures due to its thickness. By heating the fuel oil, its viscosity decreases, which allows it to flow more easily through pipes and equipment. This is crucial for ensuring efficient fuel delivery to the combustion system, especially in marine and industrial applications where pump performance is key.

While other options can be considered, such as evaporation or changes in density, these are not the primary reasons for heating fuel oil before pumping. Heating does not decrease the temperature or significantly affect the oil in a manner that would cause substantial evaporation at typical pumping conditions. Instead, the main goal of the heating process is to make handling and transferring the oil more effective by improving its flow characteristics.