LP pipe sizing and pressure

[davanz]

Hello, I am new to this forum as well as new to all things propane. I have on order a Generac 22KW air cooled and am getting the site ready. The propane tank will be installed in about three weeks. It will be thirty feet from the generator. What size copper tubing should I use. The propane supplier tells me 5/8 inch will be adequate, and I have no reason to doubt this, but I would like to have some confirmation before I install it.

Also, the propane supplier says the pressure from the regulator on the storage tank to the generator will be about 10 PSI. Using an online conversion calculator, this seems to equal to about 26 inches of water column. Is this too high for the regulator within the generator?

Thanks in advance for any education.

[Chris]

Typically the LP company will size both regulators and the line between them. 10 PSI is about 277 inches of water so I'm thinking the calculator was off by a factor of 10.

I would HIGHLY recommend involving a licensed mechanical person who can help with the sizing and install of the gas lines. There are many things to take into consideration when doing a gas install!

To answer your question, yes, 277 inches of water is WAY too much for your generator. They require between 10-12 inches.

[davanz]

You caught my error. I meant to type 276 inches not 26.

And yes, I believe the Generac specifies the delivery to be 10-12 inches, so something is amiss.

[murphy]

You need a two regulator system. A regulator at the tank that drops tank pressure to 10 psi. Then a second regulator near the generator that drops 10 psi to 10" water column. The pipe between the regulators in my system is 1/2" copper. It is only 10' long. The copper pipe is inside of a yellow plastic and is installed underground.

The regulator in the generator does not drop the pressure. It is an on-off regulator. It is called a demand regulator. When the engine demands gas the regulator turns on.

[grsthegreat]

Here in idaho they run plastic pipe underground between tank and generator. Almost always run 3/4” plastic pipe so they can expand system to include house later if need be. Then transitions to black iron pipe after it leaves ground at secondary regulator.

Also, here in N Idaho, the propane companies install all underground pipe and supply both regulators. I am responsible for the connection between secondary regulator and generator.

I havnt seen copper piping used in propane for over 20 years. On the one I did see, the propane company told us it needed to be replaced.

[Birken Vogt]

Here in California they also use plastic pipe UG, but I know copper is used in other parts of the country. I suspect the propane company did not like it because they were not used to it, and there are not enough gray hairs left in any industry to know older or different ways, everybody just thinks the way out of the book they read 2 years ago must be the only way to do it.

Of course with the price of copper now, who cares anyway, plastic all the way.

[davanz]

First, thanks for the responses.

Last evening I talked to my propane provider again and got clarification. It is true that the regulator at the tank drops the pressure to 10 PSI. But I didn't know that they will install another one within two feet of the generator to drop the pressure to12-14 inches of water. Thus, two regulators between the tank and the generator, as mentioned in another post above.

You now know that when I mentioned in my first post that I am new to all things propane, I was correct, but I am learning. Any more thoughts on 5/8 tubing being adequate for a 30' run to the 22 KW unit?
.

[Birken Vogt]

5/8 is fine at that distance at 10 psi. But the second stage regulator needs to be 5 FEET from a source of ignition (the genset) in any direction and they ought to know that. And manufacturers want there to be a significant volume of low pressure gas pipe between the regulator and generator inlet to smooth out pressure variations. Regulators are not instantaneous acting.

I have not had problems in this second area but you might as well do it right. Everyone except us violates the first area but that does not make it right.

[etemplet]

I'm likin this thread. I have a 13kw and am considering installing it at home so I'll be following this.

[grsthegreat]

You’ll love this. Just saw it today. 22kw not producing full power.

55080736-1181-4EE3-9263-18C5227D7497.jpeg (126.99 KiB) Viewed 32411 times

CAN YOU FIND THE PROBLEM.. oh, it’s natural gas.