The article is about calculating the main parameters of air - hydraulic hoods with a diaphragm to reduce the emergency consequences of a water hammer, possible in the pressure pipelines of an irrigation pumping station. Based on the results of numerical studies by the method of finite differences of the proposed hydraulic shock absorber, dependencies were obtained based on a certain air in the absorbers, the total capacity of the cylindrical cap was determined to determine the main dimensions of the absorbers. Based on the results of numerical studies by the method of finite differences of the proposed hydraulic shock absorber, dependencies were obtained based on a certain air in the absorbers, the total capacity of the cylindrical cap was determined to determine the main dimensions of the absorbers. To determine the economic dimensions of the proposed cap design, comparative calculations of numerical experiments with experimental data prove the reliability of the proposed dependencies using the finite difference method.