Abstract
Experimental data for air flow through square-edged circular orifices and their correlation with the pressure difference, the orifice diameter, and the air temperature are presented in nomographic form. The correlation holds well for small orifices with diameters ranging from 1/16 to 3/16 in., for pressure differences from 0.015 to 0.500 in. of water, and negligible velocity of approach. The air-temperature range within which the correlation can be applied is from 70 to 300 F, and corrections for barometric pressures from 27 to 32 in. of mercury can be made. The main use of this correlation will be found in its application to oil-burner design. By inclusion of the carbon-hydrogen-ratio criterion, the nomographic representation may be integrated with the system of combustion calculations, based upon the carbon-hydrogen ratio developed by the authors (1). The nomograph enables the designer to calculate the theoretical fuel rate at which any hydrocarbon fuel can be burned per square inch of air-orifice area at a given pressure difference across orifices of known diameter and at specified air temperature, air pressure, and air humidity.
