Generator Exhaust Piping 2

[atlguy06]

Hello all. First Post. I have a problem with a generator exhaust pipe in a confined space. The pipe exists the muffler with an ID of 10 inches. My question is about a 90-degree sweep vs. a 90-degree fitting, and how much more back pressure will be given by the 90-degree fitting vs. the 90-degree sweep? Am I really gaining that much by going with the sweep? Also, is it that much trouble for a mechanical contractor to make the sweep? I also thought about using two 45-degree fittings with some straight pipe to ease the turn. Thanks!

 

[mechengdude]

The back pressure question is really a question for the generator manufacturer. I've used a generator on a much smaller scale and had the same question. The generator manufacturer Onan indicated backpressure was a non-issue. This was for a 12Kw commercial generator.

For a contractor that has a welder and pipe fitter worth anything they should have no trouble fabricating a pretty elaborate pipe but do you need to?

 

[TheBlacksmith]

Not enough information, but if the exhaust ID is 10 inches at the muffler, this is probably a large machine and probably turbocharged and the sharp bend may affect it. I glanced at a handbook and the losses in a tight bend are approximately 4 times that of a large radius bend. Best to contact the OEM, they have charts/graphs/programs to calculate losses in exhaust piping

 

[RossABQ]

Two 45's have more combined loss than one long-radius 90. Each 45 is about 60% of a 90.

Depending on the overall system, it may be more advantageous and economical to simply upsize to 12" pipe than fabricate anything fancy...