Calculation question

[cdafd]

Not hydraulics expert

First set of calcs show system pressure of 50 with system demand of 487 gpm

Resubmit added backflow with fixed 3 pdi loss and calcs changed to:

System pressure of 53 and system demand of 483

Do the calcs jive , do I need to worry abut them or good to go??

Thanks

 

[SprinklerDesigner2]

I would question the difference in demand but it is possible given they may have changed something in the overhead to compensate for the added head loss.

In short something changed in addition to just adding the backflow assembly.

 

[cdafd]

At one node the pipe diameter went from
1.38. To 1.44

 

[skdesigner]

1.38 is ID for 1 1/4" Sch. 40 steel
1.44 is ID for 1 1/4" Sch. 10 steel

Seems like they plan to throw a stick of lightwall in to make up some pressure loss from the backflow. Sch. 10 is allowed by NFPA 13, but possibly not by the front end spec. Good to double check.

 

[cdafd]

Thanks
Already an interesting retrofit

Now have to look at each piece of pipe on inspection