Probability Method Applied To Determine Water Supply Design Second Flow Inside Of Buildings

Probability method applied to determine water supply design second flow inside of buildings is reliable and in accord with the practical water use condition, which is becoming a trend in the research of second flow all over the world. The calculating methods in the present codes are not uniform. Square root method and simultaneously water supply percentage coefficient method are still used for non-residential construction and regional factors are not considered in the calculation of second flow of residential construction so there are many problems and faults in this method.A new method of calculation of second flow, which is in accordance with our national condition, is give in the paper on the base of researches of design second flow inside of buildings in some countries and probability method at home, which is listed as followed:1) In view of the vast territory and the imbalance of developments, all kinds of factors influencing probability of fixture water use are analyzed. The climate and urban development situation are the main factors influencing the probability of fixture water use. By comparing the ensemble domestic water flow norm of different zones, the regional influence coefficient is given, which can be inquired by chart. At the same time the in doors domestic water flow norm and the out doors domestic water flow norm are uniformed.2) Program on base of binomial distribution principle is employed to calculate the simultaneously water supply fixture unit and design second flow. Fitting the original datum, N～P～Qg relational chart is finally given. Considering the reliability of water feed system and acceptable degree of water supply discontinuous, water supply factor of assurance is 0.99 in the paper.3) By the probability method used in the research of design second flow of residential construction, the calculating method of design second flow of public buildings such as office building, hotel, shopping mall and so on is studied. as a consequence the choosing of people load of per plumbing fixtures unit is vital for the calculation of water use probability of public buildings.Essentially, probability method applied to determine water supply design second flow inside of buildings is semi-theoretical and semi-empirical method. For residence construction a good result can be achieved as shown in the paper. The paper shows that for public buildings the probability method should be use to calculate the design second flow and the result is in accordance with the practical condition.