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Propane line for Onan 30KW


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  #1  
Old 02-03-2017, 10:53:34 PM
nothingbutdarts nothingbutdarts is online now
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Default Propane line for Onan 30KW

I had a guy out from my propane co, I have about 125' of line to run from tank to generator, the guy said they run this kind of flex line that will only be 1/2" but they run it at 50 psi in it. Then once it get my pipe set from the generator out of the building which will be about 5' long of 3/4" black pipe they will put in a reducing regulator on my pipe. He said the 1/2" line will supply plenty of volume. I told him the generator needs up to 220 CFH at full load, he said no problem!

Does this sound like it will work? Thanks!
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Old 02-04-2017, 12:02:22 AM
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Default Re: Propane line for Onan 30KW

They'll install a 10PSI primary regulator at the tank and an 11"WC regulator at the 3/4" pipe. Not to worry. You'll have plenty of fuel.
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Old 02-04-2017, 03:19:33 AM
Ray Lynch Ray Lynch is offline
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Default Re: Propane line for Onan 30KW

Darts
What model set is it?
Ray
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Old 02-04-2017, 04:00:35 AM
len k len k is online now
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Default Re: Propane line for Onan 30KW

Sounds like a 12 JC, 15JC is ~290k btu/hr

No real experience, but 10 psi is the highest I've heard of for a propane line.
Would think at 50 psi if line breaks and ignites it starts sounding like a flame thrower, all but not liquid.

Remember reading at cold temps high pressure can cause vapor to liquefy in the line. Not good, at very least causes surging in pressure in the following reg as liquid passes thru it and vaporizes. Think I read 10 psi eliminates that possibility (for most of the 48 states). Looking at a propane temp/pressure chart, propane at 10 psi can be can be ~ minus 21 deg F before it liquefies , at 50 psi it'll liquify at ~ plus 28 degs F. Maybe you can bury it deep , but think about the above ground pipe and reg. May get cold where you are and especially a mile up.
http://virtualmark.net/wx/pressure.htm

Got to run the real numbers but suspect you'll never run out of fuel at 10 psi. That's about 20 X normal 11 inches propane pressure. GUESSING at 10 psi you can lose 9 psi in the line (90% pressure loss) and reg at end of line will still be able to provide 11 inches of pressure for the demand reg. See what min input pressure for reg at end of line is (before demand reg).

Last edited by len k; 02-04-2017 at 05:07:34 AM.
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Old 02-04-2017, 05:47:22 AM
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Default Re: Propane line for Onan 30KW

Yes, that should work fine.

For a long run, best to go with a smaller diameter line at high pressure and reduce it at the point of usage.

Sounds like your gas supplier is on top of his game.
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Old 02-04-2017, 10:13:48 AM
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Default Re: Propane line for Onan 30KW

It's an SK.

Thanks for the replies guys! I could have been off on the 50 psi and apologize for that. I didn't write it down and the memory kind of sucks!
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Old 02-04-2017, 10:30:29 AM
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Default Re: Propane line for Onan 30KW

No problem.

In this case, 10 psi can be considered high pressure and would still be good.
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Old 02-04-2017, 10:33:58 AM
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Default Re: Propane line for Onan 30KW

Quote:
Originally Posted by len k View Post
Sounds like a 12 JC, 15JC is ~290k btu/hr
Len k, in my T-015 gaseous manual dated 2-1987 it lists a 15.0 JC @
110 CFH @ full load for both liquid and vapor LPG. Just putting that out there.

Now for natural gas it lists a 15.0 JC @ 255CFH.
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Old 02-04-2017, 11:11:49 AM
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Default Re: Propane line for Onan 30KW

The largest LPG sets I run are 50kw and they are plumbed with 1/2" steel pipe up to 100' distant from the actual gensets. The pipe pressure is @ 10psi leaving the pressure vessel, (tank) and reduced to 11"wc at the building entrance. We also incorporate heated atomizers in the line right before the secondary regulation, (pressure reduction) takes place to ensure smooth gaseous fuel flow in cold weather. We do not bring liquid, or high pressure gas into the facility and this allows for less expense for automated fire alarm and atmosphere monitoring for the end user.

Forgot to mention the interior piping is upsized to either 1.250" above 30kw, or upsized to .750" below 25kw as per specification(s). I always run the larger 1.250" for everything interior so well covered regardless. Remember to wrap all buried piping with environmental covering designed for this purpose and keep it deep enough it won't be crushed by weight, or dug up accidently by someone in the future. I'm not involved with residential installs so always trench 36" deep.
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Old 02-04-2017, 11:52:23 AM
Birken Vogt Birken Vogt is offline
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Default Re: Propane line for Onan 30KW

Do you install anodes on your steel pipe? I always use poly pipe with anodeless risers for new underground. Too hard to properly protect and recoat steel fittings plus it is just harder to work with in general. I would not install without anodes any more than I would install a buried tank without anodes and that requires periodic monitoring.
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