Jet fires are one of the major hazards in the oil and gas industry, and half of the reported jet fires caused a domino effect that enlarged the incident. Previous work with propane focused on vertical jet fires. In this work, both horizontal and vertical fires were studied through 21 tests conducted at the Brayton Fire Training Field. The fires were sustained by either vapor or liquid propane. The visualization of flames using both video and infrared cameras identified that cylindrical shape was a good description of vertical and horizontal jet fires. For the vertical fires, a correlation was developed for radiation against distance from the flame axis. For horizontal fires, the solid flame model was used to predict radiation; the selected parameters were evaluated by statistical performance measures. The effects of vapor flow rate, surface emissive power, and the fraction of radiation were also studied.