Abstract: This invention relates to pulsating devices which are used for converting a low continuous flow to a high intermittent pulsating flow. The pulsating device consists of an insert, an elastic tube and a casing that is without venting perforations at its outer periphery. The casing surrounds the elastic tube and forms a space between the inner surface of the rigid casing and the outer surface of the elastic tube. By using a casing which has a large space relative to the change in volume of the elastic tube, expansion of the elastic tube can be done without providing venting perforations in the casing. Fluid flows into the pulsator through its inlet at a low controlled continuous flow rate and is ejected through its outlet at a high intermittent pulsating flow. In such a case the volume of air surrounding the elastic tube and enclosed in the casing is only slightly compressed during the expansion of the elastic tube which causes a negligible increase in pressure of the air surrounding the elastic tube.