A three dimensional computational fluid dynamics model, using the STAR-CD software, has been developed to simulate fluid flow in a commonly used flanged ball valve at different partially open settings. The Reynolds number (Re) range for the flow simulations was varied between 105 and 106 to simulate a variety of flow conditions. Each flow Re number is studied with three open positions for the valve, i.e., fully open, two-thirds open, and one-third open. The simulation was used to calculate two important parameters used in characterizing the flow properties in a typical valve namely the loss coefficient, K, and the flow coefficient, C. An attempt was also made to compare some of the simulation results with experimental data and available American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) data on valves. The simulations agree reasonably well with recently published experimental results and indicate that in most cases the K factor is independent of Re. The ASHRAE data for K factor values showed similar trends to the simulation but with lower values as it was only reported for gates valves. The C values show strong increases with the degree of valve opening and lesser influence by the Re number variations in the range studied