Abstract: Against the problem of current GB 50193-93, Code for Design of Carbon Dioxide Fire Extinguishing System only calculate the pressure drop of high pressure (5.17 MPa) and low pressure (2.07 MPa) system pipelines, and the influence of heat transfer on the pipe wall is not considered, this paper builds a one-dimensional homogeneous flow calculation model for the pipeline pressure drop of carbon dioxide fire extinguishing system, establishes the calculation formula of Y and Z coefficients under different system pressure conditions, and VBA code was use to realize the rapid calculation of pipeline pressure drop under different system pressure conditions. The accuracy of the model was verified by comparing with the national standard calculation results and experimental measurement results. The new model was used to quantitatively analyze the effects of frictional resistance coefficient, mass flow rate, elevation difference, and ambient temperature on the pressure drop. It was found that the lower the system initial pressure, the bigger the influence of the frictional resistance coefficient, mass flow rate and elevation difference, and the change of temperature has little effect on the pressure drop and can be basically ignored.

Key words: carbon dioxide fire extinguishing system, friction resistance coefficient, pipeline pressure drop