Hydraulic calculations of a water curtain as a pipeline with cocurrent flow

Summary

The need for water curtains arises at over load of any toxic and explosive liquids and gases; and with account for the continuous growth of overload amounts owing to the construction of new terminals it is necessary to design water curtains more and more often. The analysis of hydraulic calculations of a water curtain in a distribution pipeline is presented. When calculating through nozzles the expediency of using the widely known flow rate coefficient instead of an unknown departmental coefficient is shown. At present formulas for calculating the total flow through the water curtain nozzles and head loss in a distribution pipeline are lacking. The method of calculating such a pipeline (pipeline with concurrent flow) is known from the hydraulics. However, it cannot be used because it is suitable for the constant specific flow rate, and the specific flow rate of the water curtain is not constant. The task of making hydraulic calculations of a water curtain for a distribution pipeline has been formulated as follows: determining such pressure and flow rate values that provide for the set flow and pressure for the last (most remote) nozzle is required. When determining head losses in a distribution pipeline the flow rate value before the pipeline multiplied by the decreasing coefficient is used. It was stated that this coefficient depended on the ratio of the diameter of the distribution pipeline to the nozzle diameter. The diagram and formula describing the above-noted dependency are presented together with an example of the calculations illustrating the use of the obtained dependencies.

Key words

hydraulic design , pressure losses , firefighting water system , water curtain , distribution pipeline , flow coefficient