Vacuum Steam

Glen Aspen_2

I ran across a brief statement in an older UA Steam Manual; it cited that both supply and return lines in the vacuum system are smaller and therefore cannot be converted to any other system. I have been under the impression that only the return lines were smaller - please clarify.

nicholas bonham-carter

other system

what other system were you considering? when working properly, with all the various parts, vents etc working as they once did, are among the best systems you can have for steam. when the absence of pumps is factored in, their energy usage looks pretty good.--nbc

Dave in QCA

Usually smaller

Perhaps the word should be "usually" smaller.

For a true engineered vacuum system with a return vacuum pump, the piping was generally smaller.  Converting to steam without vacuum may cause problems.



The reason that piping sizer were smaller was that the vacuum removed all of the air from the piping.  Pushing the air out of the system is a major factor in low pressure steam pipe sizing.   Also, when the returns are running in vacuum, there is a greater pressure differential between the supply and return piping and therefore flow is assisted.  

Glen

did a bit more research -

and looked in the Dunham Manual circa 1925; specifically at the sizing tables - where the vacuum sizing tables for both the supply and return are considerably smaller than a 2 pipe & also have a much larger EDR capacity. "Always smaller" may not be true "always - but according to Dunham - they are usually smaller. thanks.