the inherent compliance of the adsorbent material in the radial direction as the screens alternately are heated and cooled the inner and outer screens expand and contract in the radial direction because they are rigid in the radial direction and alternately squeeze and release the layers of adsorbent in the radial direction the largest squeezing force occurs when the inner screen is hot the outer screen is cold and the adsorbent is hot the smallest squeezing force i e the bed is released occurs when the inner screen is cold the outer screen is hot and the adsorbent is cold the compliance of the adsorbent material accommodates the radial squeezing forces exerted by the screens and the differential thermal expansion and contraction of the adsorbent itself the intermediate screens being flexible in the radial direction move with the layers of adsorbent in the radial direction and as a result these screens impart very little additional radial squeezing force on the adsorbent if the intermediate screens were rigid in the radial direction the screens would impart significant additional radial squeezing forces on the adsorbent and potentially could crush the adsorbent as indicated the inner screen 30 and the outer screen 24 in the principal configuration shown in fig1 have unidirectional flexibility i e flexibility in the axial direction various designs for containment screens with unidirectional flexibility are described in the prior art these designs include a cylinder with a staggered slot pattern fig2 and 3 of u s pat no 4 541 851 and fig3 and 4 of u s pat no 5 827 485 a cylindrical framework of honeycomb construction fig6 of u s pat no 4 541 851 a wire web fig6 and 7 of u s pat.