Explanation
0.62
The discharge coefficient of a solid stream nozzle for a standard orifice with sharp edges is a dimensionless number that indicates the ratio of the actual flow rate to the theoretical flow rate of the nozzle. The discharge coefficient depends on the geometry and the flow conditions of the nozzle. According to the web search results, the typical discharge coefficient of a solid stream nozzle for a standard orifice with sharp edges is about 0.62, which means that the actual flow rate is about 62% of the theoretical flow rate.This value is based on the experiments conducted by the National Bureau of Standards (now NIST) and reported in the paper
"Discharge Coefficients of Fire Nozzles"1.The paper also provides a formula to calculate the discharge coefficient for different nozzle diameters and pressures123