ASTM D6448 Specification for Industrial Burner Fuels from Used Lubricating Oils
4. Classification
4.1 There are four grades of industrial burner fuel containing recycled lubricating oils covered by this specification. These grades may or may not correlate directly with similar grades in other ASTM standards. The RFO designation identifies them as Reprocessed Fuel Oils. The usage descriptions of each grade may not describe all the uses, but are included as general information. The four grades are described as follows:
4.1.1 Grade RFO4 - Primarily a blend of used lubricating oils and distillate or a reprocessed distillate product derived from used oil. It is intended for use in pressure atomizing industrial burners with no preheating. This grade of recycled oil fuel is used in many medium capacity industrial burners where ease of handling justifies the higher cost over the heavier used oil fuels.
4.1.2 Grade RFO5L - A straight (100 %) used lubricating oil blend or a used lubricating oil and distillate blend fuel of intermediate viscosity, heavier than Grade RFO4. It is intended for use both in pressure-atomizing industrial burners not requiring higher cost distillates and in burners equipped to atomize oils of higher viscosity with or without pre-heating. Its permissible viscosity range allows it to be pumped and atomized at relatively low-storage temperatures.
4.1.3 Grade RFO5H - A straight (100 %) used lubricating oil blend or a used lubricating oil and residual blend fuel, heavier than Grade RFO5L. It is intended for use in industrial burners equipped with devices that atomize oil of higher viscosity than domestic burners can handle. Preheating may be necessary in some types of equipment for burning and in colder climates for handling.
4.1.4 Grade RFO6 - A high-viscosity used lubricating oil and residual blend fuel, heavier than Grade RFO5H. It is intended for use in large industrial heaters and may require preheating in the storage tank to permit pumping. Additional preheating at the burner may be necessary to permit satisfactory atomization. The extra equipment and maintenance required to handle this fuel usually preclude its use in small installations.
5. General Requirements
5.1 The fuel oils specified herein shall contain a minimum of 25 % (volume) of used lubricating oil-derived products, the balance being a Specification D 396 fuel oil or suitable refinery stocks.
5.2 The fuel oils shall be homogeneous fluids consisting primarily of hydrocarbons. Fuel oils containing residual components shall remain uniform in storage and shall not separate by gravity or aging into layers in normal operating conditions.
NOTE 4 - Prolonged storage or equipment down time may necessitate circulation of the fuel oil in-tank to prevent such separation.
5.3 The fuel oil shall not contain excessive amounts of organic or inorganic acids, or both, and shall be free of solid or fibrous matter that could cause system handling or maintenance problems. The buyer and seller should agree on any requirements for particle size.
NOTE 5 - The fuels defined by this specification are appropriate only for burners capable of handling and combusting fuels with potentially higher metals and ash content.
6. Detailed Requirements
6.1 Grade RFO4 - The requirements for this type of fuel are presented in Table 1 and include fuels in the viscosity range below 5 mm2/s (cSt) at 100°C in accordance with Test Method D445.
6.2 Grade RFO5L - The requirements for this type of fuel are presented in Table 1 and include fuels in the viscosity range 5.0 to 8.9 mm2/s (cSt) at 100°C in accordance with Test Method D445.
6.3 Grade RFO5H - The requirements for this type of fuel are presented in Table 1 and include fuels in the viscosity range 9.0 to 14.9 mm2/s (cSt) at 100°C in accordance with Test Method D445.
6.4 Grade RFO6 - The requirements for this type of fuel are presented in Table 1 and include fuels in the viscosity range 15.0 to 50.0 mm2/s (cSt) at 100°C in accordance with Test Method D445.
NOTE 6 - In the United States, fuel must also meet Environmental Protection Agency on-specification parameters for recycled used oil fuels as defined under 40 CFR 279.11.
6.5 The properties listed in this specification are those of greatest significance in obtaining acceptable performance of the burner. Only referee test methods are shown in Table 1. (See Section 7 for alternate test methods and Appendix X1 for significance of test requirements).
6.6 A representative sample shall be obtained for testing. Practice D4057 or D4177 or other comparable sampling standards should be followed. In case of dispute, Practice D4057 shall be the referee practice. A minimum sample size of about 1 L (1 US qt) is recommended.
6.7 Testing frequency and any modifications of limiting requirements to meet special operating conditions shall be agreed upon by both the buyer and the seller.
NOTE 7 - It is possible that one or more of the parameters listed in Table 1 may be used as an indicator of when more extensive testing is required.
