| Term | Definition |
|---|
| Oil Burner | A burner for firing oil.
|
| Oil Heating and Pumping Set | A group of apparatus consisting of a heater for raising the temperature of the oil to produce the desired viscosity, and a pump for delivering the oil at the desired pressure.
|
| Operating Control | A control to start and stop the burner - must be in addition to the high limit control.
|
| Operating Pressure | The pressure at which a boiler is operated.
|
| Organic Matter | Compounds containing carbon often derived from living organisms. |
| Orifice | (1) The opening from the whirling chamber of a mechanical atomizer or the mixing chamber of a steam atomizer through which the liquid fuel is discharged. (2) A calibrated opening in a plate, inserted in a gas stream for measure velocity of flow.
|
| Orsat | A gas-analysis apparatus in which certain gaseous constituents are measured by absorption in separate chemical solution.
|
| Overpressure | Minimum operating pressure of a hot water boiler sufficient to prevent the water from steaming.
|
| Oxidation | Chemical combination with oxygen.
|
| Oxidizing Atmosphere | An atmosphere which tends to promote the oxidation of immersed materials.
|
| Oxygen Attack | Corrosion or pitting in a boiler caused by oxygen.
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