Air Bubbler Oil Lifts are a great way to regulate various fuel supplies for Waste Oil burners, some great examples are the Turk Burner and the Babington Atomizing Burner.
The schematic above shows you hot to construct one from simple materials.
The principle is as follows: Air is supplied at approximately 6 PSI from a simple low pressure air pump (A fish tank air pump is commonly used in home made devises) down a copper tube to a tee piece, the arrangement is submersed in the oil tank / reservoir to allow the bubbles to rise up the outlet tube, as the bubbles rise up the oil filled tube they push up an amount of fuel oil above them. The more air you supply the more oil is driven up with it.
The above principle can be used in so many different burner applications and situations where a controlled and constant amount of oil is required at the burner nozzle / jet. the oil once passed over the burner nozzle that remains unburned can be easily channeled back into the oil sump / tank and recycled.
Note to consider!
As oils become warmer, as they would in the above setup, they become much thinner (Less Viscous) best practise an such a system would be to monitor the fuel oil until your system is up to a stable running temperature i.e. the oil temperature ceases to rise and then set your running air pressure. A Hasty setup on such a system could cost money and indeed lives (Play safe)