bbakk
Civil/Environmental
- Mar 25, 2001
- 14
I am new to water distribution system analysis ...
When using the following equation
Qf=Qt[(Ps-Pf)/(Ps-Pt)]^0.54 to get an approximated fire flow (Qf) given a theoretical fire flow pressure (Pf)(usually 20 psi) it is my understanding that the static pressure (Ps) and residual pressure (Pt) should be measured on the hydrant being tested (no flow hydrant while one or more hydrants on the same main are opened). On page 261 in "Analysis of Water Distribution Systems" by Thomas M. Walski (1992 edition) in his example he is using the tested static pressure 60 psi (Pt) in the numerator and the residual pressure 43 psi as (Pt) in the denominator. Should the equation read
Qf=1000[(60-20)/(60-43)^0.54 rather than
Qf=1000[(60-20)/(43-20)]^0.54? I am assuming that most of you who do Water Distribution analysis have this book as it is considered one of the bibles for this field.
I have looked at other forums and it seems that a lot of people are concerned with the static and residual pressures of the hydrant(s) being flowed. Would I use the static and residual pressures on the hydrant being flowed to simulate the connection to the water main in a model when modeling back to the source in no possible (budget constraints), i.e. a reservoir and pump system connected to the node representing the fire hydrant?. I have also read Hastad's book on this subject and it seems (like most books on this subject) to leave the reader hanging out on a limb when it comes to tieing it all together... thank you in advance.
P.s. What are the best water distribution modeling books out there?
When using the following equation
Qf=Qt[(Ps-Pf)/(Ps-Pt)]^0.54 to get an approximated fire flow (Qf) given a theoretical fire flow pressure (Pf)(usually 20 psi) it is my understanding that the static pressure (Ps) and residual pressure (Pt) should be measured on the hydrant being tested (no flow hydrant while one or more hydrants on the same main are opened). On page 261 in "Analysis of Water Distribution Systems" by Thomas M. Walski (1992 edition) in his example he is using the tested static pressure 60 psi (Pt) in the numerator and the residual pressure 43 psi as (Pt) in the denominator. Should the equation read
Qf=1000[(60-20)/(60-43)^0.54 rather than
Qf=1000[(60-20)/(43-20)]^0.54? I am assuming that most of you who do Water Distribution analysis have this book as it is considered one of the bibles for this field.
I have looked at other forums and it seems that a lot of people are concerned with the static and residual pressures of the hydrant(s) being flowed. Would I use the static and residual pressures on the hydrant being flowed to simulate the connection to the water main in a model when modeling back to the source in no possible (budget constraints), i.e. a reservoir and pump system connected to the node representing the fire hydrant?. I have also read Hastad's book on this subject and it seems (like most books on this subject) to leave the reader hanging out on a limb when it comes to tieing it all together... thank you in advance.
P.s. What are the best water distribution modeling books out there?