Oil Heat Nozzles

Nozzles The nozzle prepares the fuel oil for combustion by atomizing, metering and patterning the oil. Atomizing the oil is by breaking the oil into tiny droplets through the use of pressure.

Nozzles The smallest droplets ignite first. The larger droplets provide more heat transfer when they are ignited.

Nozzle Construction The porous filter is made of brass or steel and catches any sediment that may have bypassed the tank filter and the pump strainer. The filters purpose is to prevent blockage of the nozzle orifice.

Oil Nozzle Construction

Atomization Atomization is a complex process The movement of the oil must be changed to a circular swirling motion opposite that of the airflow from the combustion head.

Atomization The fuel enters the orifice of the nozzle through the swirl chamber where this swirling motion takes affect.

Nozzle size The bore size of the orifice in the nozzle is designed to allow a certain amount of fuel to pass through at a given pressure to produce the fuel flow desired.

Nozzle size The fuel flow controls the BTU input to the appliance. Each nozzle is marked as to the amount of fuel it will deliver.

Nozzle Markings A nozzle marked 1.00 will deliver 1 gallon of no 2. oil per hour with an input pressure of 100 psi and an oil temperature of 60 degrees. A nozzle marked .8 GPH will deliver 112,000 BTU/hr

Nozzle Markings Remember, 1 gallon of no.2 oil will produce 140,000 BTU’s/hr. 140,000 X .8 = 112,000

Nozzle Pattern The nozzle must have a uniform spray pattern and an angle that is best suited for the specific burner and combustion chamber.

Spray Angle

Nozzle Pattern There are three basic spray patterns: Hollow Semi-solid Solid Each pattern can have a spray angle of 30 degrees to 90 degrees.

Nozzle Spray Angle Most common are: 30 degree 45 degree 60 degree 70 degree 80 degree 90 degree The smaller the chamber, the less the angle nozzle used.

Hollow Cone Nozzles Hollow cone nozzles usually produce a more stable spray angle and pattern than solid cone nozzles of the same flow rate do. Often used when the flow rate is less then 1GPH.

Solid Cone Nozzles Distribute droplets fairly evenly throughout the pattern. Often used on larger burners with a flow rate of greater than 1 gph.

Semi solid Nozzles Often used instead of hollow or solid cone nozzles. The higher flow rate produce a more solid spray pattern, and the lower flow rates produce a hollow spray pattern.

Nozzle Replacement The nozzle is a precision device that must be handled carefully. These nozzles are not intended for cleaning or rebuilding in the field. Cleaning with a wire brush or metal instruments will distort the passages in the nozzle.

Nozzle Replacement Handling the inlet filter leave deposits from your hands that can be pushed through the orifice. New Nozzles must be kept in their shipping containers and not allowed to roll around in the tool box.

Nozzle wrench A nozzle wrench should be used to remove the nozzle to prevent damage. This tool takes the place of the two wrenches that would otherwise be required to hold the nozzle and its adapter for removal.( usually ¾ and 5/8” wrenches)

Nozzle Performance All nozzles are rated for 100 psi of pressure. A nozzle stamped with 1.00 gph will produce 1 gph @ 100 psi. If the pressure changes the rating is no longer valid. If a 1.00 gph nozzle is used and the pump pressure is adjusted to 125 psi, the nozzle will actually be discharging 1.12 gph.

Nozzle Sizing Name plate will have the nozzle size or BTU ratings. If missing use the following: GPH = BTU INPUT/140,000 If BTU Input is missing use the output divided by 112,000 (GPH of oil at 80%)

Low Pressure A nozzle at low pressure will have A weak spray pattern Under fires burner Droplets of oil are larger and that lowers efficiency and increases smoke.

High Pressure High pressure nozzles: Create smaller droplets Increase the flow rate Are sometimes better for cold oil and ignition problems.

Effects of pressure Some manufacturers are: Using higher pump pressures, up to 300 psi. Lowering nozzle size Gaining efficiency (makes the burners burn cleaner)

Nozzle Cleanliness The nozzle wrench must be kept clean, or it will do more harm than good. Debris often packs into the wrench and can transfer to the end of the nozzle. Clean the wrench after every use to prevent this from happening.

Impingement Impingement is when the flame is touching any part of the combustion chamber. When this happens the combustion chamber will get damaged very easily and will need replacement. ( if practical) This can be caused by using the wrong size nozzle, wrong spray pattern, wrong pump pressure.

Solved Impingement