Abstract: An ambulatory infusing device including a housing, a reservoir defining an interior volume, a wall associated with the housing and having an inner surface that faces into the reservoir interior volume, and a filter assembly. The filter assembly may include a filter assembly housing with a housing filter portion having a filter supporting volume, a filter located within the filter supporting volume, and a bubble guard, including a bubble guard wall and at least one bubble guard aperture that extends through the bubble guard wall, associated with the filter assembly housing such that the bubble guard wall is located in spaced relation to the filter.