The function of the swirl ring is to spin the plasma gas which has two main results; 1, The spinning gas is gyroscopically stabilised a bit like a rifle bullet making the plasma column less tendency to deflect. 2, As cooler gas is heavier than hot gas the spinning action centrifugally places the cooler gases on the outside where they are in direct contact with the nozzle. Ionised (or plasma) gas coming into contact with the nozzle would burn it out very quickly but because of the swirl ring action and the other cooling mechanisms, a useful nozzle life is achieved. Swirl rings for mechanised cutting are available in both directions of rotation, clock-wise & counter Clock-wise. This is because one effect of the swirling plasma gas is the cut in the plate has one side vertical and the other side angled depending on the direction of torch travel.
Used on the Cebora Prof 37c, Prof 55 & CP90 Torches and others!!