Provided is an assembly for reconstitution of a substance comprising: a fluid injector (110) comprising a fluid reservoir and having a longitudinal axis a receptacle (22) defining an interior volume and having a longitudinal axis and a pressure equalizing device (10) connected between the fluid injector (110) and the receptacle (22) having a longitudinal axis, the pressure equalizing device (10) comprising: a container (12) for attachment to the receptacle (22), to permit pressure equalization between the container (12) and the receptacle (22), the container (12) comprising a first chamber (16) and a second chamber (14) and a fluid transfer member (24) having an access channel (30), connected between the fluid injector (110) and the interior volume of the receptacle (22), and a vent channel (28), connected between the interior volume of the receptacle (22) and the first chamber (16), wherein when the receptacle (22) is connected to the pressure equalizing device (10), the vent channel (28) establishes direct fluid communication between the first chamber (16) and the receptacle (22), and wherein the longitudinal axis of the pressure equalizing device (10), the longitudinal axis of the receptacle (22), and the longitudinal axis of the fluid injector (110) are aligned with or parallel to each other.
