Oxygen pipe sizing

[Dacc]

Good morning,

For the sizing of the pipes of an oxygen system, can I use the same chart of the compressed air pipe sizing? Can i use it also for the sizing of natural gas and LPG system?

The sizing shall be based on the flow and the available pressure, is there any additional factor that should be considered?

Thank you,
Chady.

 

[BigInch]

Velocities should be held to <= 25 fps in steel pipelines.

You probably have a computer, since you're managing to write this question here, so why use a chart that might not account for appropriate pressure, temperatures and molecular weights? I think it would be much better to find an online gas flow calculator you like and use that.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[btrueblood]

see

http://smad-ext.grc.nasa.gov/gso/manual/chapter_05.pdf

There are risks of ignition if flow velocities are too high, especially if particulates impinge on pipe walls at those velocities.

 

[BigInch]

30 fps is the typical limit. That's why I reduced it by 17%

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[drywall]

Dacc,

As BigInch and btrueblood have recognized there can be ignition mechanisms within the oxygen piping network if you do not use proper materials and keep safe velocities. I strongly suggest that you do not take your design any further until you get a copy of CGA G-4.4 or EIGA IGC Doc 13/02/E and read it from end to end. You will be glad you did.

 

[racookpe1978]

He did not report desired oxygen pipe pressure, flow rate, pipe diameter, temperature and temperature range, not service.

We are assuming "normal" modestly high pressures, medium diameter pipes, and (the usual US-standards in pipe internal cleanliness) in cautioning about auto-ignition. He should check his actual conditions.

 

[crjones]

The NASA document referenced by btrueblood has a pipe line velocity of 100 fps. How do the lower velocities Biginch are stating come into play?

 

[btrueblood]

NASA document references cleanliness standards far beyond the filter-and-forget-it level, and use of low-ignitable materials throughout system. They are also intended at least in part for flight systems where weight is at a premium, or in test systems, both of which also are places where safety and inspection during use are of paramount importance, so have tested with the above caveats to higher velocities.

BigInch's numbers are from CGA (industry) standards, which are probably developed using much more "worst case" conditions, or at least from worser-case background failure data (dirtier pipes, poor maintenance, and lawsuit-happy Yankee cowboys using the system), and so are much more conservative to keep the underwriters happy.