This report describes the laboratory development and testing of the improved sprayfan auxiliary ventilation system. The sprayfan system, based on the fact that water sprays can move air like small fans, consists of several spray manifolds strategically placed on continuous miners to direct intake air to the face and sweep contaminated air (methane and dust) across the face to the return. Water spray systems using sprayfan principles have been installed on more than 300 continuous miners. Although the improved sprayfan system operates on the same principles as the original sprayfan system, the layout and number of spray nozzles differ, providing additional water for dust suppression. A detailed description of the test facility, evaluation techniques, and system test results is provided in this report. The effect of methane monitor placement and instrument lag on the indicated methane reading was also assessed. The results of two major field evaluations of the improved sprayfan system are given.