Friction Loss

Katherine,
The friction loss is calculated based on the flow and velocity you have set for that valve. Please take a look at the link below for an overview and description of this dialog box.

Size Lateral Pipe Dialog

Thank you, Jake. I already actually reviewed that page before I posted and didn't see information on how the two numbers I asked about were generated. Could you please point me to which section(s) I should be looking at?

Katherine,

You are right, that page does not provide a complete definition of Friction Loss. It is the loss generated through the length of pipe from the valve to the farthest head, as per the inside diameters of the pipe class chosen, the velocity specified, and the results of the Hazen-Williams formula.

---J

Thank you. To clarify, the number that comes up in bold halfway down on the pipe sizing dialogue box ("Friction Loss: 2.13 PSI") is the friction loss that occurs in all the lateral pipe in the zone, and this is calculated using the Hazen-Williams formula based on length of pipe drawn, pipe diameter (selected automatically by LandFX based on available pipe sizes I entered in the pipe data menu), and velocity.

It seems like velocity is based on the pipe diameters that landfx selects, so I don't specify velocity directly, but I can input the maximum velocity in the slider on the pipe sizing dialogue box. Is that correct?

..and..

Is "Loss through Valve" at the bottom of the pipe sizing dialogue box, in a dropdown box, calculated based on the valve I selected and GPM of the zone?

Correct on the loss through valve, and the clarification.

The maximum velocity works in conjunction with the Pressure Variation -- if the friction loss is larger than the allowable pressure variation, the system will reduce the velocity.

--J

Got it, thank you so much!