| Indirect-Fired, Thermal-Oil-Jacketed Melter | A burner heats thermal oil, which circulates through a jacket around the melting vessel. The oil transfers heat to the asphalt without direct flame contact with the product. | Generally even across the jacketed vessel, helping reduce localized overheating when the system is properly designed and operated. | Batch melting of asphalt or bituminous materials where controlled, steady heating is important. | Requires a thermal-fluid circuit and regular inspection of the burner, fluid, pump, and temperature controls. Actual performance depends on vessel design, loading, and circulation. |
| Direct-Fired Kettle | A burner applies heat directly to the outside bottom or sides of the kettle. | Heat is concentrated near the heated surfaces; mixing and careful temperature control can help limit temperature differences within the material. | Small-scale or jobsite melting, subject to the equipment’s capacity and applicable safety requirements. | Operators need to monitor material temperature and avoid prolonged heating or inadequate mixing, which can contribute to scorching or uneven melting. |
| Electric-Resistance Melter | Electrical resistance elements heat the vessel, a jacket, or another heat-transfer surface. | Can provide controlled heating; uniformity depends on element placement, vessel design, and whether the material is mixed. | Installations where a suitable electrical supply is available and combustion heating is not preferred. | Heating capacity is limited by the available electrical service and equipment rating. Electrical protection and temperature controls must be appropriate for the installation. |
| Heated-Grid Block Melter | A heated grid melts compatible solid asphalt or bitumen blocks as material passes through or over the grid and collects in a receiving vessel. | Heat is applied at the grid surface; melting rate and consistency depend on grid temperature, block contact, and material feed. | Processing solid blocks or packaged bituminous material in systems designed for that feed format. | Confirm that the material and packaging are suitable for the unit. Grid design, feeding method, and downstream temperature control affect operation. |