This experimental database aimed to study the influence of the orifice plate position and area contraction ratio on the air-water slug flow in a horizontal orientation. Three orifices with different area contraction ratios and three different setups were tested. The database contains the raw and post-processed pressure and dual impedance probe data in a fully instrumented test section. The superficial velocity of the liquid was 0.30 m/s, and the gas was 0.50 m/s.