Abstract: A pressure relief valve for use with flexible containers holding coffee, especially ground coffee, is disclosed. The valve incorporates a unique two piece structural arrangement that requires a low level of precision compared to similar valves. The valve comprises a valve body including a valve chamber having a resilient diaphragm located therein for opening and closing the valve. A set of valve retainers formed integral with the valve body ensure that the diaphragm remains within the valve chamber. A viscous liquid helps ensure an air-tight seal and also acts to retain the diaphragm against a valve seat within the valve chamber. Inlet slots are sized and shaped to effectively prevent coffee grounds from entering the valve without need of a filter or filter paper.