44 and bottom panel 45 which forms beveled bottom edge 46 top panel 42 side panels 44 and bottom panel 45 of swing seal 40 are disposed around the periphery of front panel 47 interior face 50 fig9 of front panel 47 faces towards the direction of chamber 6 and exterior face 48 fig6 of front panel 47 faces toward the product stack to be loaded further side panels 44 define a thickness when swing seal 40 is in an at rest position such that a product stack is not disposed against swing seal 40 face 48 of front panel 47 protrudes forwardly from wall 30 at a distance corresponding to or less than the thickness of side panels 44 referring to fig7 when product stack 52 is disposed against intake opening 54 of wall 30 swing seal 40 yieldably moves by pivoting rearwardly towards an interior of chamber 6 via rotating about a horizontal axis from a rest position to a seal position alternative designs of the swing seal may yieldably move rearwardly towards the interior of chamber 6 along a horizontal plane and for example against a spring biased force in the seal position as further described below swing seal 40 the pair of side periphery seals 36 and bottom horizontal frame member 34 defining the lower seal create the seal between product stack 52 and intake opening 54 as mentioned above the product stacks may vary in height as shown by the different product stacks of fig6 and 10 for example to cooperate with the swing seal of the present disclosure the product stack may have a height ranging from a first height measured from floor 60 to just.