Metal Raschig ring is the oldest regular packing and is still used today for many applications in mass transfer applications but commonly for refilling existing columns.Friedrich Raschig invented the rings in the 1880s but did not patent them until the 1910s. Due to simple cylindrical shaped tube with an aspect ratio of 1:1, liquid liquid will move in the thousands of channels formed by the rings, coating the inside and outside surfaces, and eventually flowing to the bottom. Gas entering at the bottom will flow through the same paths formed by the rings, and will have time to contact and react with the liquid.

However, Owing to metal Raschig ring’s inside is a cylinder with open ends, it is difficult to follow into Metal Raschig Ring’s inside for liquid. Finally, its mass transfer efficiency is lower than others. It has replaced by Metal Pall ring slowly.