Patent US 4,176,791

An irrigation system of the type comprising a plurality of nozzles spaced along a pipeline fed at one end from a source of supply of irrigation liquid, which latter may be purely water or may be water with additives, in which in order to avoid different spray rates due to a loss in pressure along the pipeline each nozzle is provided with a valve and an associated resilient subsidiary reservoir, the valves operating to close off the nozzles while all the subsidiary reservoirs charge up to the line pressure and then, when a control valve diverts the source of supply to a discharge outlet all the nozzles receive liquid in the same pressure from their associated subsidiary reservoir; when the subsidiary reservoirs are all back at atmospheric pressure the cycle recommences.