A home use carbonation machine includes a pronged clamp to fit a non-upright bottle to a flexible seal, thereby facilitating a closed carbonation environment in the bottle and a normally open safety valve to vent the bottle when the carbonation machine is not actively carbonating. A home use carbonation machine includes a carbonation assembly to carbonate liquid with pressurized gas, a pronged clamp and a centering ring with centering ribs to guide a non-upright bottle into the pronged clamp during insertion and to constrict prongs of the clamp when a user moves the non-upright bottle towards an upright position for operation.