Steam Line Sizing
Steam Line Sizing
(OP)
When sizing a steam line to an AHU coil, should the branch lines going to the ahu coil be the same size as the coil connection size or is it ok to use a smaller size? When using the size charts it looks like a smaller size would be acceptable but I think I remember reading somewhere that individual branch lines should be the same size as the coil connection.





RE: Steam Line Sizing
Katmar Software
Engineering & Risk Analysis Software
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RE: Steam Line Sizing
Perform a pressure drop calculation along your steam pipeline and evaluate the most suitable pipe diameter in order to ensure your AHU coil is fed with the required steam flow rate at the required pressure.
RE: Steam Line Sizing
Size for pressure drop and increase/decrease to coil piping size.
RE: Steam Line Sizing
With steamlines it's usually the flowspeed of the steam that is the limiting factor, not pressure drop (IMHO).
RE: Steam Line Sizing
Pressure drop is related to velocity. I agree there are recommended velocities that one shouldn't exceed because of erosion issues (25 m/s for saturated steam and up to 70-80 m/s for superheated steam). Anyway the coil is rated for a certain pressure of steam, that is for a set temperature, and not for a set velocity.
RE: Steam Line Sizing
Ione,
I guess we are both thinking exactly the same thing.
Properties of the flow change at every point along the pipe: hands up anyone who is solving the integral for any old steamline going to the odd steamcoil instead of just getting out a simple table based on maximum flowspeed and kg/s going through the pipe?
RE: Steam Line Sizing
Short lines can be sized on velocity. Long runs, like several hundred feet, normally need to be sized on pressure drop.