Embossed support member with high and low skip ribs

An embossed and elongated flexible support member for use in a coil dialyzer for supporting an elongated semipermeable membrane, which membrane is characterized by stretching further in the transverse direction than in the longitudinal direction, said support member comprising:

• an elongated imperforate impermeable web;
• means on one side of said web defining a plurality of angle ribs for engaging and supporting said membrane and for cooperation in defining a plurality of angular flow channels;
• means on the other side of said web defining a plurality of high skip ribs and a plurality of low skip ribs, said high ribs and said low ribs being arranged in longitudinally extending rows with the ribs in each row being spaced from each other, with the rows of low skip ribs being positioned intermediate the rows of high skip ribs, and the spacing between ribs in a row cooperating in defining sinuous flow channels through said rows;
• and
• the height of said high skip ribs being uniformly greater than the height of substantially all said angle ribs, said low skip ribs being of a height lower than the height of said high skip ribs and said angle ribs wherein the height and space between said ribs and the shape of said ribs cooperate with the membrane to form channels on either side of the membrane of substantially equal flow rates.