Studies on flame propagation during turbulent deflagration in a partly opened tube are important in developing explosion protection scheme and suppression technology for industrial process with explosion risk. Gas explosions in coal mines, deflagration in gas transmission tubes and dust explosions in confined working spaces can be simplified by a partly opened tube in studying deflagrations. An experimental rig with a 16 m long open tube of 0.488 m diameter was constructed for studying the flame propagation characteristics of premixed liquefied petroleum gas (LPG) under different mixing ratios with air. The transient flame propagation distance, flame velocity, pressure and temperature were analyzed. A flame velocity model for an explosion in an open tube was proposed and verified by the experimental data. This model was also used to calculate the flame velocity of experiments reported in literature. It is demonstrated that the developed flame velocity model is appropriate for premixed gas deflagrations up to an equivalence ratio of 1 at the initial stage of flame propagation, i.e., with a flame velocity less than 100 m/s. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.