Analysis of setting plan and running condition in variable water flow system

The necessity of applying variable water flow systems is analyzed. Variable water flow systems and their theory of energy-saving are recommended. Factors affecting constant pressure difference control method and advantages and disadvantages of the control plan are analyzed theoretically through pipe system head curve and pump performance curve. Running conditions of parallel-connected variable and constant speed pump are discussed using pump performance curve, and the correct switch steps are pointed out. Conclusions are drawn that the more the value of the constant pressure difference is, the less the effects of the control plan are, and vice versa; and that the improved plan based on valve lift and variable pressure difference has sensible effects of energy-saving; and that the energy-saving effect of parallel-connected variable and constant speed pumps is more sensible than that of constant speed pumps.