Prediction correlations of air bubble diameter and frequency in stagnant clean water were established. Eleven different orifice diameters were tested under flow rate of 0.05–0.15 SLPM. The resulted bubble size and frequency were traced using high-speed camera. It was found that the mean Sauter diameter and bubble frequency are in the range of 3.7–6.9 mm and 6.4–47.2 bubbles per second, respectively. Nonlinear regression was performed to design the new correlations of estimating diameter and frequency with a correlation factor of 0.93 and 0.94, respectively. Flow rate and orifice size had the highest impact on the studied parameters.