Pressure drop formula used in API 14E for single phase gas lines

[DoraeS]

Hi,
Does anyone know what is the basis for pressure drop formula (equation 2.6) stated in API 14E 5th Edition, section 2.4 for single phase gas line? Is it derived for isothermal flow (more conservative) or adiabatic flow?
Thanks.

 

[CJKruger]

llc0612, I had a quick look and it seems to be a simplified isothermal equation.

My personal view is that the isothermal equation should not be simplified this way (it reduces accuracy and you need inlet+outlet conditions anyway).