Propane tank

[Pakal]

Hi there, I do not have natural gas supply where I live , I could only connect a 100 lb Propane gas round tank to the generator. What gas regulator do I need to use between the tank and the generator ?
Pakal

[Pakal]

Hi again Kelly, I never got an answer to my question. Would a simple regulator, like the one I use to supply my stove, be OK for the generator. Furthermore the GPL tank will only supply the generator . How long would it last (100 lb) if connected to a 7kw or a 10kw guardian ?
Thanks for your time,

Pasquale

[Kelly Myers]

Hi Pakal, sorry for overlooking your question!

1st off, I'm NO fuel expert, I'm just an electrician. :) What we have experienced with 100 lb tanks, is they freeze up! I'm sitting on my deck, so I don't have my stat sheets, but the 7/10kw should be around a gallon/hour @ 50% load. I will correct this number on monday. I'm not sure how a pound resolves to gallons. I really wish someone who knows fuel could start posting here! I might have to find somebody to help out!

I'm not sure if the normal household regulator will work, because I believe you normally need two. One to drop pressure, and one to adjust W.C.

[cosmicvoid]

I'm not a fuel expert, either, but recently I did a lot of research on regulators and gas flow. You do need two stages of regulation for LPG. The first stage (red housing) drops the tank pressure (25~200 psi) down to 10 psi, the second stage (green housing) drops the 10 psi down to 11"wc. It is common to see integral 2 stage regulators that combine both into one gray housing.

Here is a pdf catalog from a valve company, but in the middle section, about pages 71~87, there is a large amount of really useful info about how the valves/regulators work, and tables for gas flow, pipe sizing, etc. It will probably answer many of your questions. There is a 'rule of thumb' chart for gas flow vs temperature and tank shape (surface area of liquid propane), and a lot of discussion about 100 lb DOT cylinders, and freeze-up.

http://www.sherwoodvalve.com/pdf/lpg.pdf

Hope this helps.

[irq3]

Take a look at this webpage:
http://www.propane-generators.com/lp_gas.htm

(Rules of thumb)
*It requires 2 horsepower to produce 1000 watts of energy per hour

*Under load, each horsepower consumes 10,000 BTU per hour

*LP Gas contains 92,000 BTU per gallon

The regulator size you need depends on the size of the generator (they are rated in BTU's/ HR).

For example: a 4,000 watt generator = 8 HP engine X 10,000 BTU/HR = 80,000 BTU/HR (full load). The example would need a regulator capable of handling 80,000 BTU/ HR capacity.

Pay special attention the "Vaporization Rates of Cylinders" (at 25% full) chart too. Depending on the size of the generator, if you live in a colder climate, the 100# cylinder may be too small (and freeze up).

As for needing a two stage regulator, it also depends on the BTU/HR load, distance to the propane tank, and the size of the gas line. You may be able to use a single stage regulator (11-14" WC).

This site also has a hook up hose sizing chart:
http://www.propane-generators.com/hook-up_hoses.htm

Remember, the NFPA gas code requires a propane tank to be at least 10 feet away from a combustible source (generator, etc.). Also, use a rubber flexible hose to connect the generator (vibration)!

Your best bet may be to lease a 420# tank and regulator from a gas company, have them install and fill it as needed. Usually, you get a better price on propane when buying in bulk or pre-buy.